diff --git a/chain/vm/runtime.go b/chain/vm/runtime.go
index 6e94030bd..72f4daab8 100644
--- a/chain/vm/runtime.go
+++ b/chain/vm/runtime.go
@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/binary"
 	"fmt"
+	"os"
 	gruntime "runtime"
 	"time"
 
@@ -52,7 +53,7 @@ func (m *Message) ValueReceived() abi.TokenAmount {
 }
 
 // EnableGasTracing, if true, outputs gas tracing in execution traces.
-var EnableGasTracing = false
+var EnableGasTracing = os.Getenv("LOTUS_VM_ENABLE_GAS_TRACING_VERY_SLOW") == "1"
 
 type Runtime struct {
 	rt5.Message
diff --git a/cmd/lotus-miner/retrieval-deals.go b/cmd/lotus-miner/retrieval-deals.go
index 1ce1f6593..bd5d30a4e 100644
--- a/cmd/lotus-miner/retrieval-deals.go
+++ b/cmd/lotus-miner/retrieval-deals.go
@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"os"
+	"sort"
 	"text/tabwriter"
 
 	"github.com/docker/go-units"
@@ -137,6 +138,10 @@ var retrievalDealsListCmd = &cli.Command{
 			return err
 		}
 
+		sort.Slice(deals, func(i, j int) bool {
+			return deals[i].ID < deals[j].ID
+		})
+
 		w := tabwriter.NewWriter(os.Stdout, 2, 4, 2, ' ', 0)
 
 		_, _ = fmt.Fprintf(w, "Receiver\tDealID\tPayload\tState\tPricePerByte\tBytesSent\tMessage\n")
diff --git a/extern/sector-storage/fr32/fr32.go b/extern/sector-storage/fr32/fr32.go
index 17e6a1142..24175719c 100644
--- a/extern/sector-storage/fr32/fr32.go
+++ b/extern/sector-storage/fr32/fr32.go
@@ -8,7 +8,7 @@ import (
 	"github.com/filecoin-project/go-state-types/abi"
 )
 
-var MTTresh = uint64(32 << 20)
+var MTTresh = uint64(512 << 10)
 
 func mtChunkCount(usz abi.PaddedPieceSize) uint64 {
 	threads := (uint64(usz)) / MTTresh
diff --git a/extern/sector-storage/fr32/readers.go b/extern/sector-storage/fr32/readers.go
index f14d5bf1c..163c520aa 100644
--- a/extern/sector-storage/fr32/readers.go
+++ b/extern/sector-storage/fr32/readers.go
@@ -16,13 +16,21 @@ type unpadReader struct {
 	work []byte
 }
 
+func BufSize(sz abi.PaddedPieceSize) int {
+	return int(MTTresh * mtChunkCount(sz))
+}
+
 func NewUnpadReader(src io.Reader, sz abi.PaddedPieceSize) (io.Reader, error) {
+	buf := make([]byte, BufSize(sz))
+
+	return NewUnpadReaderBuf(src, sz, buf)
+}
+
+func NewUnpadReaderBuf(src io.Reader, sz abi.PaddedPieceSize, buf []byte) (io.Reader, error) {
 	if err := sz.Validate(); err != nil {
 		return nil, xerrors.Errorf("bad piece size: %w", err)
 	}
 
-	buf := make([]byte, MTTresh*mtChunkCount(sz))
-
 	return &unpadReader{
 		src: src,
 
diff --git a/extern/sector-storage/mock/mock.go b/extern/sector-storage/mock/mock.go
index eeb1404ad..8eaed54f6 100644
--- a/extern/sector-storage/mock/mock.go
+++ b/extern/sector-storage/mock/mock.go
@@ -12,6 +12,7 @@ import (
 
 	proof5 "github.com/filecoin-project/specs-actors/v5/actors/runtime/proof"
 
+	"github.com/filecoin-project/dagstore/mount"
 	ffiwrapper2 "github.com/filecoin-project/go-commp-utils/ffiwrapper"
 	commcid "github.com/filecoin-project/go-fil-commcid"
 	"github.com/filecoin-project/go-state-types/abi"
@@ -384,12 +385,22 @@ func generateFakePoSt(sectorInfo []proof5.SectorInfo, rpt func(abi.RegisteredSea
 	}
 }
 
-func (mgr *SectorMgr) ReadPiece(ctx context.Context, sector storage.SectorRef, offset storiface.UnpaddedByteIndex, startOffset uint64, size abi.UnpaddedPieceSize, ticket abi.SealRandomness, unsealed cid.Cid) (io.ReadCloser, bool, error) {
+func (mgr *SectorMgr) ReadPiece(ctx context.Context, sector storage.SectorRef, offset storiface.UnpaddedByteIndex, size abi.UnpaddedPieceSize, ticket abi.SealRandomness, unsealed cid.Cid) (mount.Reader, bool, error) {
 	if uint64(offset) != 0 {
 		panic("implme")
 	}
 
-	return ioutil.NopCloser(bytes.NewReader(mgr.pieces[mgr.sectors[sector.ID].pieces[0]][startOffset:size])), false, nil
+	br := bytes.NewReader(mgr.pieces[mgr.sectors[sector.ID].pieces[0]][:size])
+
+	return struct {
+		io.ReadCloser
+		io.Seeker
+		io.ReaderAt
+	}{
+		ReadCloser: ioutil.NopCloser(br),
+		Seeker:     br,
+		ReaderAt:   br,
+	}, false, nil
 }
 
 func (mgr *SectorMgr) StageFakeData(mid abi.ActorID, spt abi.RegisteredSealProof) (storage.SectorRef, []abi.PieceInfo, error) {
diff --git a/extern/sector-storage/piece_provider.go b/extern/sector-storage/piece_provider.go
index aa2ef0d0d..4622289e8 100644
--- a/extern/sector-storage/piece_provider.go
+++ b/extern/sector-storage/piece_provider.go
@@ -8,6 +8,7 @@ import (
 	"github.com/ipfs/go-cid"
 	"golang.org/x/xerrors"
 
+	"github.com/filecoin-project/dagstore/mount"
 	"github.com/filecoin-project/go-state-types/abi"
 	"github.com/filecoin-project/specs-storage/storage"
 
@@ -27,7 +28,7 @@ type PieceProvider interface {
 	//  default in most cases, but this might matter with future PoRep)
 	// startOffset is added to the pieceOffset to get the starting reader offset.
 	// The number of bytes that can be read is pieceSize-startOffset
-	ReadPiece(ctx context.Context, sector storage.SectorRef, pieceOffset storiface.UnpaddedByteIndex, startOffset uint64, pieceSize abi.UnpaddedPieceSize, ticket abi.SealRandomness, unsealed cid.Cid) (io.ReadCloser, bool, error)
+	ReadPiece(ctx context.Context, sector storage.SectorRef, pieceOffset storiface.UnpaddedByteIndex, pieceSize abi.UnpaddedPieceSize, ticket abi.SealRandomness, unsealed cid.Cid) (mount.Reader, bool, error)
 	IsUnsealed(ctx context.Context, sector storage.SectorRef, offset storiface.UnpaddedByteIndex, size abi.UnpaddedPieceSize) (bool, error)
 }
 
@@ -71,37 +72,91 @@ func (p *pieceProvider) IsUnsealed(ctx context.Context, sector storage.SectorRef
 // It will NOT try to schedule an Unseal of a sealed sector file for the read.
 //
 // Returns a nil reader if the piece does NOT exist in any unsealed file or there is no unsealed file for the given sector on any of the workers.
-func (p *pieceProvider) tryReadUnsealedPiece(ctx context.Context, sector storage.SectorRef, pieceOffset, startOffset storiface.UnpaddedByteIndex, size abi.UnpaddedPieceSize) (io.ReadCloser, context.CancelFunc, error) {
+func (p *pieceProvider) tryReadUnsealedPiece(ctx context.Context, pc cid.Cid, sector storage.SectorRef, pieceOffset storiface.UnpaddedByteIndex, size abi.UnpaddedPieceSize) (mount.Reader, error) {
 	// acquire a lock purely for reading unsealed sectors
 	ctx, cancel := context.WithCancel(ctx)
 	if err := p.index.StorageLock(ctx, sector.ID, storiface.FTUnsealed, storiface.FTNone); err != nil {
 		cancel()
-		return nil, nil, xerrors.Errorf("acquiring read sector lock: %w", err)
+		return nil, xerrors.Errorf("acquiring read sector lock: %w", err)
 	}
 
-	// Reader returns a reader for an unsealed piece at the given offset in the given sector.
+	// Reader returns a reader getter for an unsealed piece at the given offset in the given sector.
 	// The returned reader will be nil if none of the workers has an unsealed sector file containing
 	// the unsealed piece.
-	r, err := p.storage.Reader(ctx, sector, abi.PaddedPieceSize(pieceOffset.Padded()+startOffset.Padded()), size.Padded()-abi.PaddedPieceSize(startOffset.Padded()))
+	rg, err := p.storage.Reader(ctx, sector, abi.PaddedPieceSize(pieceOffset.Padded()), size.Padded())
 	if err != nil {
+		cancel()
 		log.Debugf("did not get storage reader;sector=%+v, err:%s", sector.ID, err)
-		cancel()
-		return nil, nil, err
+		return nil, err
 	}
-	if r == nil {
+	if rg == nil {
 		cancel()
+		return nil, nil
 	}
 
-	return r, cancel, nil
+	buf := make([]byte, fr32.BufSize(size.Padded()))
+
+	pr, err := (&pieceReader{
+		ctx: ctx,
+		getReader: func(ctx context.Context, startOffset uint64) (io.ReadCloser, error) {
+			startOffsetAligned := storiface.UnpaddedByteIndex(startOffset / 127 * 127) // floor to multiple of 127
+
+			r, err := rg(startOffsetAligned.Padded())
+			if err != nil {
+				return nil, xerrors.Errorf("getting reader at +%d: %w", startOffsetAligned, err)
+			}
+
+			upr, err := fr32.NewUnpadReaderBuf(r, size.Padded(), buf)
+			if err != nil {
+				r.Close() // nolint
+				return nil, xerrors.Errorf("creating unpadded reader: %w", err)
+			}
+
+			bir := bufio.NewReaderSize(upr, 127)
+			if startOffset > uint64(startOffsetAligned) {
+				if _, err := bir.Discard(int(startOffset - uint64(startOffsetAligned))); err != nil {
+					r.Close() // nolint
+					return nil, xerrors.Errorf("discarding bytes for startOffset: %w", err)
+				}
+			}
+
+			return struct {
+				io.Reader
+				io.Closer
+			}{
+				Reader: bir,
+				Closer: funcCloser(func() error {
+					return r.Close()
+				}),
+			}, nil
+		},
+		len:      size,
+		onClose:  cancel,
+		pieceCid: pc,
+	}).init()
+	if err != nil || pr == nil { // pr == nil to make sure we don't return typed nil
+		cancel()
+		return nil, err
+	}
+
+	return pr, err
 }
 
+type funcCloser func() error
+
+func (f funcCloser) Close() error {
+	return f()
+}
+
+var _ io.Closer = funcCloser(nil)
+
 // ReadPiece is used to read an Unsealed piece at the given offset and of the given size from a Sector
 // If an Unsealed sector file exists with the Piece Unsealed in it, we'll use that for the read.
 // Otherwise, we will Unseal a Sealed sector file for the given sector and read the Unsealed piece from it.
 // If we do NOT have an existing unsealed file  containing the given piece thus causing us to schedule an Unseal,
 // the returned boolean parameter will be set to true.
 // If we have an existing unsealed file containing the given piece, the returned boolean will be set to false.
-func (p *pieceProvider) ReadPiece(ctx context.Context, sector storage.SectorRef, pieceOffset storiface.UnpaddedByteIndex, startOffset uint64, size abi.UnpaddedPieceSize, ticket abi.SealRandomness, unsealed cid.Cid) (io.ReadCloser, bool, error) {
+func (p *pieceProvider) ReadPiece(ctx context.Context, sector storage.SectorRef, pieceOffset storiface.UnpaddedByteIndex, size abi.UnpaddedPieceSize, ticket abi.SealRandomness, unsealed cid.Cid) (mount.Reader, bool, error) {
 	if err := pieceOffset.Valid(); err != nil {
 		return nil, false, xerrors.Errorf("pieceOffset is not valid: %w", err)
 	}
@@ -109,9 +164,7 @@ func (p *pieceProvider) ReadPiece(ctx context.Context, sector storage.SectorRef,
 		return nil, false, xerrors.Errorf("size is not a valid piece size: %w", err)
 	}
 
-	startOffsetAligned := storiface.UnpaddedByteIndex(startOffset / 127 * 127) // floor to multiple of 127
-
-	r, unlock, err := p.tryReadUnsealedPiece(ctx, sector, pieceOffset, startOffsetAligned, size)
+	r, err := p.tryReadUnsealedPiece(ctx, unsealed, sector, pieceOffset, size)
 
 	log.Debugf("result of first tryReadUnsealedPiece: r=%+v, err=%s", r, err)
 
@@ -142,7 +195,7 @@ func (p *pieceProvider) ReadPiece(ctx context.Context, sector storage.SectorRef,
 
 		log.Debugf("unsealed a sector file to read the piece, sector=%+v, pieceOffset=%d, size=%d", sector, pieceOffset, size)
 
-		r, unlock, err = p.tryReadUnsealedPiece(ctx, sector, pieceOffset, startOffsetAligned, size)
+		r, err = p.tryReadUnsealedPiece(ctx, unsealed, sector, pieceOffset, size)
 		if err != nil {
 			log.Errorf("failed to tryReadUnsealedPiece after SectorsUnsealPiece: %s", err)
 			return nil, true, xerrors.Errorf("read after unsealing: %w", err)
@@ -156,34 +209,7 @@ func (p *pieceProvider) ReadPiece(ctx context.Context, sector storage.SectorRef,
 		log.Debugf("unsealed piece already exists, no need to unseal, sector=%+v, pieceOffset=%d, size=%d", sector, pieceOffset, size)
 	}
 
-	upr, err := fr32.NewUnpadReader(r, size.Padded())
-	if err != nil {
-		unlock()
-		return nil, uns, xerrors.Errorf("creating unpadded reader: %w", err)
-	}
+	log.Debugf("returning reader to read unsealed piece, sector=%+v, pieceOffset=%d, size=%d", sector, pieceOffset, size)
 
-	log.Debugf("returning reader to read unsealed piece, sector=%+v, pieceOffset=%d, startOffset=%d, size=%d", sector, pieceOffset, startOffset, size)
-
-	bir := bufio.NewReaderSize(upr, 127)
-	if startOffset > uint64(startOffsetAligned) {
-		if _, err := bir.Discard(int(startOffset - uint64(startOffsetAligned))); err != nil {
-			return nil, false, xerrors.Errorf("discarding bytes for startOffset: %w", err)
-		}
-	}
-
-	return &funcCloser{
-		Reader: bir,
-		close: func() error {
-			err = r.Close()
-			unlock()
-			return err
-		},
-	}, uns, nil
+	return r, uns, nil
 }
-
-type funcCloser struct {
-	io.Reader
-	close func() error
-}
-
-func (fc *funcCloser) Close() error { return fc.close() }
diff --git a/extern/sector-storage/piece_provider_test.go b/extern/sector-storage/piece_provider_test.go
index 1aad3d2d2..3ace2916e 100644
--- a/extern/sector-storage/piece_provider_test.go
+++ b/extern/sector-storage/piece_provider_test.go
@@ -338,7 +338,7 @@ func (p *pieceProviderTestHarness) isUnsealed(t *testing.T, offset storiface.Unp
 
 func (p *pieceProviderTestHarness) readPiece(t *testing.T, offset storiface.UnpaddedByteIndex, size abi.UnpaddedPieceSize,
 	expectedHadToUnseal bool, expectedBytes []byte) {
-	rd, isUnsealed, err := p.pp.ReadPiece(p.ctx, p.sector, offset, 0, size, p.ticket, p.commD)
+	rd, isUnsealed, err := p.pp.ReadPiece(p.ctx, p.sector, offset, size, p.ticket, p.commD)
 	require.NoError(t, err)
 	require.NotNil(t, rd)
 	require.Equal(t, expectedHadToUnseal, isUnsealed)
diff --git a/markets/dagstore/piecereader.go b/extern/sector-storage/piece_reader.go
similarity index 88%
rename from markets/dagstore/piecereader.go
rename to extern/sector-storage/piece_reader.go
index 67cd10c27..d7a3f4e98 100644
--- a/markets/dagstore/piecereader.go
+++ b/extern/sector-storage/piece_reader.go
@@ -1,4 +1,4 @@
-package dagstore
+package sectorstorage
 
 import (
 	"bufio"
@@ -19,11 +19,14 @@ import (
 var MaxPieceReaderBurnBytes int64 = 1 << 20 // 1M
 var ReadBuf = 128 * (127 * 8)               // unpadded(128k)
 
+type pieceGetter func(ctx context.Context, offset uint64) (io.ReadCloser, error)
+
 type pieceReader struct {
-	ctx      context.Context
-	api      MinerAPI
-	pieceCid cid.Cid
-	len      abi.UnpaddedPieceSize
+	ctx       context.Context
+	getReader pieceGetter
+	pieceCid  cid.Cid
+	len       abi.UnpaddedPieceSize
+	onClose   context.CancelFunc
 
 	closed bool
 	seqAt  int64 // next byte to be read by io.Reader
@@ -37,10 +40,14 @@ func (p *pieceReader) init() (_ *pieceReader, err error) {
 	stats.Record(p.ctx, metrics.DagStorePRInitCount.M(1))
 
 	p.rAt = 0
-	p.r, p.len, err = p.api.FetchUnsealedPiece(p.ctx, p.pieceCid, uint64(p.rAt))
+	p.r, err = p.getReader(p.ctx, uint64(p.rAt))
 	if err != nil {
 		return nil, err
 	}
+	if p.r == nil {
+		return nil, nil
+	}
+
 	p.br = bufio.NewReaderSize(p.r, ReadBuf)
 
 	return p, nil
@@ -60,12 +67,19 @@ func (p *pieceReader) Close() error {
 	}
 
 	if p.r != nil {
+		if err := p.r.Close(); err != nil {
+			return err
+		}
 		if err := p.r.Close(); err != nil {
 			return err
 		}
 		p.r = nil
 	}
 
+	p.onClose()
+
+	p.closed = true
+
 	return nil
 }
 
@@ -127,7 +141,7 @@ func (p *pieceReader) ReadAt(b []byte, off int64) (n int, err error) {
 		}
 
 		p.rAt = off
-		p.r, _, err = p.api.FetchUnsealedPiece(p.ctx, p.pieceCid, uint64(p.rAt))
+		p.r, err = p.getReader(p.ctx, uint64(p.rAt))
 		p.br = bufio.NewReaderSize(p.r, ReadBuf)
 		if err != nil {
 			return 0, xerrors.Errorf("getting backing reader: %w", err)
diff --git a/extern/sector-storage/stores/http_handler.go b/extern/sector-storage/stores/http_handler.go
index 5996392d8..771a9a3a1 100644
--- a/extern/sector-storage/stores/http_handler.go
+++ b/extern/sector-storage/stores/http_handler.go
@@ -84,7 +84,6 @@ func (handler *FetchHandler) remoteStatFs(w http.ResponseWriter, r *http.Request
 // remoteGetSector returns the sector file/tared directory byte stream for the sectorID and sector file type sent in the request.
 // returns an error if it does NOT have the required sector file/dir.
 func (handler *FetchHandler) remoteGetSector(w http.ResponseWriter, r *http.Request) {
-	log.Infof("SERVE GET %s", r.URL)
 	vars := mux.Vars(r)
 
 	id, err := storiface.ParseSectorID(vars["id"])
diff --git a/extern/sector-storage/stores/remote.go b/extern/sector-storage/stores/remote.go
index 7935556a9..bd6b34be3 100644
--- a/extern/sector-storage/stores/remote.go
+++ b/extern/sector-storage/stores/remote.go
@@ -585,7 +585,7 @@ func (r *Remote) CheckIsUnsealed(ctx context.Context, s storage.SectorRef, offse
 // 1. no worker(local worker included) has an unsealed file for the given sector OR
 // 2. no worker(local worker included) has the unsealed piece in their unsealed sector file.
 // Will return a nil reader and a nil error in such a case.
-func (r *Remote) Reader(ctx context.Context, s storage.SectorRef, offset, size abi.PaddedPieceSize) (io.ReadCloser, error) {
+func (r *Remote) Reader(ctx context.Context, s storage.SectorRef, offset, size abi.PaddedPieceSize) (func(startOffsetAligned storiface.PaddedByteIndex) (io.ReadCloser, error), error) {
 	ft := storiface.FTUnsealed
 
 	// check if we have the unsealed sector file locally
@@ -623,7 +623,52 @@ func (r *Remote) Reader(ctx context.Context, s storage.SectorRef, offset, size a
 
 		if has {
 			log.Infof("returning piece reader for local unsealed piece sector=%+v, (offset=%d, size=%d)", s.ID, offset, size)
-			return r.pfHandler.Reader(pf, storiface.PaddedByteIndex(offset), size)
+
+			return func(startOffsetAligned storiface.PaddedByteIndex) (io.ReadCloser, error) {
+				// don't reuse between readers unless closed
+				f := pf
+				pf = nil
+
+				if f == nil {
+					f, err = r.pfHandler.OpenPartialFile(abi.PaddedPieceSize(ssize), path)
+					if err != nil {
+						return nil, xerrors.Errorf("opening partial file: %w", err)
+					}
+					log.Debugf("local partial file (re)opened %s (+%d,%d)", path, offset, size)
+				}
+
+				r, err := r.pfHandler.Reader(f, storiface.PaddedByteIndex(offset)+startOffsetAligned, size-abi.PaddedPieceSize(startOffsetAligned))
+				if err != nil {
+					return nil, err
+				}
+
+				return struct {
+					io.Reader
+					io.Closer
+				}{
+					Reader: r,
+					Closer: funcCloser(func() error {
+						// if we already have a reader cached, close this one
+						if pf != nil {
+							if f == nil {
+								return nil
+							}
+							if pf == f {
+								pf = nil
+							}
+
+							tmp := f
+							f = nil
+							return tmp.Close()
+						}
+
+						// otherwise stash it away for reuse
+						pf = f
+						return nil
+					}),
+				}, nil
+			}, nil
+
 		}
 
 		log.Debugf("miner has unsealed file but not unseal piece, %s (+%d,%d)", path, offset, size)
@@ -666,16 +711,18 @@ func (r *Remote) Reader(ctx context.Context, s storage.SectorRef, offset, size a
 				continue
 			}
 
-			// readRemote fetches a reader that we can use to read the unsealed piece from the remote worker.
-			// It uses a ranged HTTP query to ensure we ONLY read the unsealed piece and not the entire unsealed file.
-			rd, err := r.readRemote(ctx, url, offset, size)
-			if err != nil {
-				log.Warnw("reading from remote", "url", url, "error", err)
-				lastErr = err
-				continue
-			}
-			log.Infof("Read remote %s (+%d,%d)", url, offset, size)
-			return rd, nil
+			return func(startOffsetAligned storiface.PaddedByteIndex) (io.ReadCloser, error) {
+				// readRemote fetches a reader that we can use to read the unsealed piece from the remote worker.
+				// It uses a ranged HTTP query to ensure we ONLY read the unsealed piece and not the entire unsealed file.
+				rd, err := r.readRemote(ctx, url, offset+abi.PaddedPieceSize(startOffsetAligned), size)
+				if err != nil {
+					log.Warnw("reading from remote", "url", url, "error", err)
+					return nil, err
+				}
+
+				return rd, err
+			}, nil
+
 		}
 	}
 
@@ -692,3 +739,11 @@ func (r *Remote) Reserve(ctx context.Context, sid storage.SectorRef, ft storifac
 }
 
 var _ Store = &Remote{}
+
+type funcCloser func() error
+
+func (f funcCloser) Close() error {
+	return f()
+}
+
+var _ io.Closer = funcCloser(nil)
diff --git a/extern/sector-storage/stores/remote_test.go b/extern/sector-storage/stores/remote_test.go
index ea9179655..0bc439dee 100644
--- a/extern/sector-storage/stores/remote_test.go
+++ b/extern/sector-storage/stores/remote_test.go
@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
@@ -470,12 +471,20 @@ func TestReader(t *testing.T) {
 
 			remoteStore := stores.NewRemote(lstore, index, nil, 6000, pfhandler)
 
-			rd, err := remoteStore.Reader(ctx, sectorRef, offset, size)
+			rdg, err := remoteStore.Reader(ctx, sectorRef, offset, size)
+			var rd io.ReadCloser
 
 			if tc.errStr != "" {
-				require.Error(t, err)
-				require.Nil(t, rd)
-				require.Contains(t, err.Error(), tc.errStr)
+				if rdg == nil {
+					require.Error(t, err)
+					require.Nil(t, rdg)
+					require.Contains(t, err.Error(), tc.errStr)
+				} else {
+					rd, err = rdg(0)
+					require.Error(t, err)
+					require.Nil(t, rd)
+					require.Contains(t, err.Error(), tc.errStr)
+				}
 			} else {
 				require.NoError(t, err)
 			}
@@ -483,7 +492,10 @@ func TestReader(t *testing.T) {
 			if !tc.expectedNonNilReader {
 				require.Nil(t, rd)
 			} else {
-				require.NotNil(t, rd)
+				require.NotNil(t, rdg)
+				rd, err := rdg(0)
+				require.NoError(t, err)
+
 				defer func() {
 					require.NoError(t, rd.Close())
 				}()
diff --git a/go.mod b/go.mod
index d0685be51..45cefb7a2 100644
--- a/go.mod
+++ b/go.mod
@@ -90,6 +90,7 @@ require (
 	github.com/ipfs/go-ipfs-util v0.0.2
 	github.com/ipfs/go-ipld-cbor v0.0.6
 	github.com/ipfs/go-ipld-format v0.2.0
+	github.com/ipfs/go-ipld-legacy v0.1.1 // indirect
 	github.com/ipfs/go-log/v2 v2.4.0
 	github.com/ipfs/go-merkledag v0.5.1
 	github.com/ipfs/go-metrics-interface v0.0.1
@@ -156,14 +157,16 @@ require (
 	go.uber.org/fx v1.9.0
 	go.uber.org/multierr v1.7.0
 	go.uber.org/zap v1.19.1
-	golang.org/x/net v0.0.0-20210917221730-978cfadd31cf
+	golang.org/x/crypto v0.0.0-20211209193657-4570a0811e8b // indirect
+	golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2
 	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c
-	golang.org/x/sys v0.0.0-20211007075335-d3039528d8ac
+	golang.org/x/sys v0.0.0-20211209171907-798191bca915
 	golang.org/x/time v0.0.0-20210723032227-1f47c861a9ac
 	golang.org/x/tools v0.1.5
 	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1
 	gopkg.in/cheggaaa/pb.v1 v1.0.28
 	gotest.tools v2.2.0+incompatible
+	lukechampine.com/blake3 v1.1.7 // indirect
 )
 
 replace github.com/filecoin-project/filecoin-ffi => ./extern/filecoin-ffi
diff --git a/go.sum b/go.sum
index 5ecad5936..e18478aab 100644
--- a/go.sum
+++ b/go.sum
@@ -774,8 +774,9 @@ github.com/ipfs/go-ipld-format v0.0.1/go.mod h1:kyJtbkDALmFHv3QR6et67i35QzO3S0dC
 github.com/ipfs/go-ipld-format v0.0.2/go.mod h1:4B6+FM2u9OJ9zCV+kSbgFAZlOrv1Hqbf0INGQgiKf9k=
 github.com/ipfs/go-ipld-format v0.2.0 h1:xGlJKkArkmBvowr+GMCX0FEZtkro71K1AwiKnL37mwA=
 github.com/ipfs/go-ipld-format v0.2.0/go.mod h1:3l3C1uKoadTPbeNfrDi+xMInYKlx2Cvg1BuydPSdzQs=
-github.com/ipfs/go-ipld-legacy v0.1.0 h1:wxkkc4k8cnvIGIjPO0waJCe7SHEyFgl+yQdafdjGrpA=
 github.com/ipfs/go-ipld-legacy v0.1.0/go.mod h1:86f5P/srAmh9GcIcWQR9lfFLZPrIyyXQeVlOWeeWEuI=
+github.com/ipfs/go-ipld-legacy v0.1.1 h1:BvD8PEuqwBHLTKqlGFTHSwrwFOMkVESEvwIYwR2cdcc=
+github.com/ipfs/go-ipld-legacy v0.1.1/go.mod h1:8AyKFCjgRPsQFf15ZQgDB8Din4DML/fOmKZkkFkrIEg=
 github.com/ipfs/go-ipns v0.1.2 h1:O/s/0ht+4Jl9+VoxoUo0zaHjnZUS+aBQIKTuzdZ/ucI=
 github.com/ipfs/go-ipns v0.1.2/go.mod h1:ioQ0j02o6jdIVW+bmi18f4k2gRf0AV3kZ9KeHYHICnQ=
 github.com/ipfs/go-log v0.0.1/go.mod h1:kL1d2/hzSpI0thNYjiKfjanbVNU+IIGA/WnNESY9leM=
@@ -1964,8 +1965,9 @@ golang.org/x/crypto v0.0.0-20210513164829-c07d793c2f9a/go.mod h1:P+XmwS30IXTQdn5
 golang.org/x/crypto v0.0.0-20210616213533-5ff15b29337e/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.0.0-20210813211128-0a44fdfbc16e/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
-golang.org/x/crypto v0.0.0-20210915214749-c084706c2272 h1:3erb+vDS8lU1sxfDHF4/hhWyaXnhIaO+7RgL4fDZORA=
 golang.org/x/crypto v0.0.0-20210915214749-c084706c2272/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/crypto v0.0.0-20211209193657-4570a0811e8b h1:QAqMVf3pSa6eeTsuklijukjXBlj7Es2QQplab+/RbQ4=
+golang.org/x/crypto v0.0.0-20211209193657-4570a0811e8b/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
 golang.org/x/exp v0.0.0-20180321215751-8460e604b9de/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20180807140117-3d87b88a115f/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20181106170214-d68db9428509/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
@@ -2073,8 +2075,9 @@ golang.org/x/net v0.0.0-20210428140749-89ef3d95e781/go.mod h1:OJAsFXCWl8Ukc7SiCT
 golang.org/x/net v0.0.0-20210525063256-abc453219eb5/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20210614182718-04defd469f4e/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20210813160813-60bc85c4be6d/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/net v0.0.0-20210917221730-978cfadd31cf h1:R150MpwJIv1MpS0N/pc+NhTM8ajzvlmxlY5OYsrevXQ=
 golang.org/x/net v0.0.0-20210917221730-978cfadd31cf/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2 h1:CIJ76btIcR3eFI5EgSo6k1qKw9KJexJuRLI9G7Hp5wE=
+golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20181017192945-9dcd33a902f4/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20181203162652-d668ce993890/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
@@ -2196,8 +2199,8 @@ golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210816183151-1e6c022a8912/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210917161153-d61c044b1678/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20211007075335-d3039528d8ac h1:oN6lz7iLW/YC7un8pq+9bOLyXrprv2+DKfkJY+2LJJw=
-golang.org/x/sys v0.0.0-20211007075335-d3039528d8ac/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20211209171907-798191bca915 h1:P+8mCzuEpyszAT6T42q0sxU+eveBAF/cJ2Kp0x6/8+0=
+golang.org/x/sys v0.0.0-20211209171907-798191bca915/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20201210144234-2321bbc49cbf h1:MZ2shdL+ZM/XzY3ZGOnh4Nlpnxz5GSOhOmtHo3iPU6M=
@@ -2451,8 +2454,9 @@ honnef.co/go/tools v0.0.1-2020.1.4/go.mod h1:X/FiERA/W4tHapMX5mGpAtMSVEeEUOyHaw9
 honnef.co/go/tools v0.1.3/go.mod h1:NgwopIslSNH47DimFoV78dnkksY2EFtX0ajyb3K/las=
 howett.net/plist v0.0.0-20181124034731-591f970eefbb h1:jhnBjNi9UFpfpl8YZhA9CrOqpnJdvzuiHsl/dnxl11M=
 howett.net/plist v0.0.0-20181124034731-591f970eefbb/go.mod h1:vMygbs4qMhSZSc4lCUl2OEE+rDiIIJAIdR4m7MiMcm0=
-lukechampine.com/blake3 v1.1.6 h1:H3cROdztr7RCfoaTpGZFQsrqvweFLrqS73j7L7cmR5c=
 lukechampine.com/blake3 v1.1.6/go.mod h1:tkKEOtDkNtklkXtLNEOGNq5tcV90tJiA1vAA12R78LA=
+lukechampine.com/blake3 v1.1.7 h1:GgRMhmdsuK8+ii6UZFDL8Nb+VyMwadAgcJyfYHxG6n0=
+lukechampine.com/blake3 v1.1.7/go.mod h1:tkKEOtDkNtklkXtLNEOGNq5tcV90tJiA1vAA12R78LA=
 modernc.org/cc v1.0.0 h1:nPibNuDEx6tvYrUAtvDTTw98rx5juGsa5zuDnKwEEQQ=
 modernc.org/cc v1.0.0/go.mod h1:1Sk4//wdnYJiUIxnW8ddKpaOJCF37yAdqYnkxUpaYxw=
 modernc.org/fileutil v1.0.0/go.mod h1:JHsWpkrk/CnVV1H/eGlFf85BEpfkrp56ro8nojIq9Q8=
diff --git a/lib/tracing/setup.go b/lib/tracing/setup.go
index 1a2d8128e..d90099f79 100644
--- a/lib/tracing/setup.go
+++ b/lib/tracing/setup.go
@@ -11,6 +11,7 @@ import (
 	"go.opentelemetry.io/otel/sdk/resource"
 	tracesdk "go.opentelemetry.io/otel/sdk/trace"
 	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
+	"go.uber.org/zap"
 
 	logging "github.com/ipfs/go-log/v2"
 )
@@ -50,7 +51,7 @@ func jaegerOptsFromEnv() jaeger.EndpointOption {
 	}
 
 	if e, ok = os.LookupEnv(envAgentHost); ok {
-		options := []jaeger.AgentEndpointOption{jaeger.WithAgentHost(e)}
+		options := []jaeger.AgentEndpointOption{jaeger.WithAgentHost(e), jaeger.WithLogger(zap.NewStdLog(log.Desugar()))}
 		var ep string
 		if p, ok := os.LookupEnv(envAgentPort); ok {
 			options = append(options, jaeger.WithAgentPort(p))
@@ -82,6 +83,7 @@ func SetupJaegerTracing(serviceName string) *tracesdk.TracerProvider {
 			semconv.SchemaURL,
 			semconv.ServiceNameKey.String(serviceName),
 		)),
+		tracesdk.WithSampler(tracesdk.AlwaysSample()),
 	)
 	otel.SetTracerProvider(tp)
 	tracer := tp.Tracer(serviceName)
diff --git a/markets/dagstore/miner_api.go b/markets/dagstore/miner_api.go
index d59a05846..77b4b97bf 100644
--- a/markets/dagstore/miner_api.go
+++ b/markets/dagstore/miner_api.go
@@ -3,22 +3,22 @@ package dagstore
 import (
 	"context"
 	"fmt"
-	"io"
 
-	"github.com/filecoin-project/dagstore/throttle"
-	"github.com/filecoin-project/go-state-types/abi"
 	"github.com/ipfs/go-cid"
 	"golang.org/x/xerrors"
 
+	"github.com/filecoin-project/dagstore/mount"
+	"github.com/filecoin-project/dagstore/throttle"
 	"github.com/filecoin-project/go-fil-markets/piecestore"
 	"github.com/filecoin-project/go-fil-markets/retrievalmarket"
 	"github.com/filecoin-project/go-fil-markets/shared"
+	"github.com/filecoin-project/go-state-types/abi"
 )
 
 //go:generate go run github.com/golang/mock/mockgen -destination=mocks/mock_lotus_accessor.go -package=mock_dagstore . MinerAPI
 
 type MinerAPI interface {
-	FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid, offset uint64) (io.ReadCloser, abi.UnpaddedPieceSize, error)
+	FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid) (mount.Reader, error)
 	GetUnpaddedCARSize(ctx context.Context, pieceCid cid.Cid) (uint64, error)
 	IsUnsealed(ctx context.Context, pieceCid cid.Cid) (bool, error)
 	Start(ctx context.Context) error
@@ -27,7 +27,7 @@ type MinerAPI interface {
 type SectorAccessor interface {
 	retrievalmarket.SectorAccessor
 
-	UnsealSectorAt(ctx context.Context, sectorID abi.SectorNumber, pieceOffset abi.UnpaddedPieceSize, startOffset uint64, length abi.UnpaddedPieceSize) (io.ReadCloser, error)
+	UnsealSectorAt(ctx context.Context, sectorID abi.SectorNumber, pieceOffset abi.UnpaddedPieceSize, length abi.UnpaddedPieceSize) (mount.Reader, error)
 }
 
 type minerAPI struct {
@@ -100,10 +100,10 @@ func (m *minerAPI) IsUnsealed(ctx context.Context, pieceCid cid.Cid) (bool, erro
 	return false, nil
 }
 
-func (m *minerAPI) FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid, offset uint64) (io.ReadCloser, abi.UnpaddedPieceSize, error) {
+func (m *minerAPI) FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid) (mount.Reader, error) {
 	err := m.readyMgr.AwaitReady()
 	if err != nil {
-		return nil, 0, err
+		return nil, err
 	}
 
 	// Throttle this path to avoid flooding the storage subsystem.
@@ -114,11 +114,11 @@ func (m *minerAPI) FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid, off
 	})
 
 	if err != nil {
-		return nil, 0, xerrors.Errorf("failed to fetch pieceInfo for piece %s: %w", pieceCid, err)
+		return nil, xerrors.Errorf("failed to fetch pieceInfo for piece %s: %w", pieceCid, err)
 	}
 
 	if len(pieceInfo.Deals) == 0 {
-		return nil, 0, xerrors.Errorf("no storage deals found for piece %s", pieceCid)
+		return nil, xerrors.Errorf("no storage deals found for piece %s", pieceCid)
 	}
 
 	// prefer an unsealed sector containing the piece if one exists
@@ -126,7 +126,7 @@ func (m *minerAPI) FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid, off
 		deal := deal
 
 		// Throttle this path to avoid flooding the storage subsystem.
-		var reader io.ReadCloser
+		var reader mount.Reader
 		err := m.throttle.Do(ctx, func(ctx context.Context) (err error) {
 			isUnsealed, err := m.sa.IsUnsealed(ctx, deal.SectorID, deal.Offset.Unpadded(), deal.Length.Unpadded())
 			if err != nil {
@@ -136,7 +136,7 @@ func (m *minerAPI) FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid, off
 				return nil
 			}
 			// Because we know we have an unsealed copy, this UnsealSector call will actually not perform any unsealing.
-			reader, err = m.sa.UnsealSectorAt(ctx, deal.SectorID, deal.Offset.Unpadded(), offset, deal.Length.Unpadded())
+			reader, err = m.sa.UnsealSectorAt(ctx, deal.SectorID, deal.Offset.Unpadded(), deal.Length.Unpadded())
 			return err
 		})
 
@@ -147,7 +147,7 @@ func (m *minerAPI) FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid, off
 
 		if reader != nil {
 			// we were able to obtain a reader for an already unsealed piece
-			return reader, deal.Length.Unpadded(), nil
+			return reader, nil
 		}
 	}
 
@@ -158,7 +158,7 @@ func (m *minerAPI) FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid, off
 		// block for a long time with the current PoRep
 		//
 		// This path is unthrottled.
-		reader, err := m.sa.UnsealSectorAt(ctx, deal.SectorID, deal.Offset.Unpadded(), offset, deal.Length.Unpadded())
+		reader, err := m.sa.UnsealSectorAt(ctx, deal.SectorID, deal.Offset.Unpadded(), deal.Length.Unpadded())
 		if err != nil {
 			lastErr = xerrors.Errorf("failed to unseal deal %d: %w", deal.DealID, err)
 			log.Warn(lastErr.Error())
@@ -166,10 +166,10 @@ func (m *minerAPI) FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid, off
 		}
 
 		// Successfully fetched the deal data so return a reader over the data
-		return reader, deal.Length.Unpadded(), nil
+		return reader, nil
 	}
 
-	return nil, 0, lastErr
+	return nil, lastErr
 }
 
 func (m *minerAPI) GetUnpaddedCARSize(ctx context.Context, pieceCid cid.Cid) (uint64, error) {
diff --git a/markets/dagstore/miner_api_test.go b/markets/dagstore/miner_api_test.go
index 38c3a4fc3..45cbf2461 100644
--- a/markets/dagstore/miner_api_test.go
+++ b/markets/dagstore/miner_api_test.go
@@ -15,6 +15,7 @@ import (
 	"github.com/stretchr/testify/require"
 	"golang.org/x/sync/errgroup"
 
+	"github.com/filecoin-project/dagstore/mount"
 	"github.com/filecoin-project/go-address"
 	"github.com/filecoin-project/go-state-types/abi"
 	"github.com/filecoin-project/specs-actors/actors/builtin/paych"
@@ -87,7 +88,7 @@ func TestLotusAccessorFetchUnsealedPiece(t *testing.T) {
 			}
 
 			// Fetch the piece
-			r, _, err := api.FetchUnsealedPiece(ctx, cid1, 0)
+			r, err := api.FetchUnsealedPiece(ctx, cid1)
 			if tc.expectErr {
 				require.Error(t, err)
 				return
@@ -159,7 +160,7 @@ func TestThrottle(t *testing.T) {
 	errgrp, ctx := errgroup.WithContext(context.Background())
 	for i := 0; i < 10; i++ {
 		errgrp.Go(func() error {
-			r, _, err := api.FetchUnsealedPiece(ctx, cid1, 0)
+			r, err := api.FetchUnsealedPiece(ctx, cid1)
 			if err == nil {
 				_ = r.Close()
 			}
@@ -203,10 +204,10 @@ type mockRPN struct {
 }
 
 func (m *mockRPN) UnsealSector(ctx context.Context, sectorID abi.SectorNumber, offset abi.UnpaddedPieceSize, length abi.UnpaddedPieceSize) (io.ReadCloser, error) {
-	return m.UnsealSectorAt(ctx, sectorID, offset, 0, length)
+	return m.UnsealSectorAt(ctx, sectorID, offset, length)
 }
 
-func (m *mockRPN) UnsealSectorAt(ctx context.Context, sectorID abi.SectorNumber, pieceOffset abi.UnpaddedPieceSize, startOffset uint64, length abi.UnpaddedPieceSize) (io.ReadCloser, error) {
+func (m *mockRPN) UnsealSectorAt(ctx context.Context, sectorID abi.SectorNumber, pieceOffset abi.UnpaddedPieceSize, length abi.UnpaddedPieceSize) (mount.Reader, error) {
 	atomic.AddInt32(&m.calls, 1)
 	m.lk.RLock()
 	defer m.lk.RUnlock()
@@ -215,7 +216,13 @@ func (m *mockRPN) UnsealSectorAt(ctx context.Context, sectorID abi.SectorNumber,
 	if !ok {
 		panic("sector not found")
 	}
-	return io.NopCloser(bytes.NewBuffer([]byte(data[startOffset:]))), nil
+	return struct {
+		io.ReadCloser
+		io.ReaderAt
+		io.Seeker
+	}{
+		ReadCloser: io.NopCloser(bytes.NewBuffer([]byte(data[:]))),
+	}, nil
 }
 
 func (m *mockRPN) IsUnsealed(ctx context.Context, sectorID abi.SectorNumber, offset abi.UnpaddedPieceSize, length abi.UnpaddedPieceSize) (bool, error) {
diff --git a/markets/dagstore/mocks/mock_lotus_accessor.go b/markets/dagstore/mocks/mock_lotus_accessor.go
index e10a1b053..19923cc2a 100644
--- a/markets/dagstore/mocks/mock_lotus_accessor.go
+++ b/markets/dagstore/mocks/mock_lotus_accessor.go
@@ -6,10 +6,9 @@ package mock_dagstore
 
 import (
 	context "context"
-	io "io"
 	reflect "reflect"
 
-	abi "github.com/filecoin-project/go-state-types/abi"
+	mount "github.com/filecoin-project/dagstore/mount"
 	gomock "github.com/golang/mock/gomock"
 	cid "github.com/ipfs/go-cid"
 )
@@ -38,19 +37,18 @@ func (m *MockMinerAPI) EXPECT() *MockMinerAPIMockRecorder {
 }
 
 // FetchUnsealedPiece mocks base method.
-func (m *MockMinerAPI) FetchUnsealedPiece(arg0 context.Context, arg1 cid.Cid, arg2 uint64) (io.ReadCloser, abi.UnpaddedPieceSize, error) {
+func (m *MockMinerAPI) FetchUnsealedPiece(arg0 context.Context, arg1 cid.Cid) (mount.Reader, error) {
 	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "FetchUnsealedPiece", arg0, arg1, arg2)
-	ret0, _ := ret[0].(io.ReadCloser)
-	ret1, _ := ret[1].(abi.UnpaddedPieceSize)
-	ret2, _ := ret[2].(error)
-	return ret0, ret1, ret2
+	ret := m.ctrl.Call(m, "FetchUnsealedPiece", arg0, arg1)
+	ret0, _ := ret[0].(mount.Reader)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
 }
 
 // FetchUnsealedPiece indicates an expected call of FetchUnsealedPiece.
-func (mr *MockMinerAPIMockRecorder) FetchUnsealedPiece(arg0, arg1, arg2 interface{}) *gomock.Call {
+func (mr *MockMinerAPIMockRecorder) FetchUnsealedPiece(arg0, arg1 interface{}) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "FetchUnsealedPiece", reflect.TypeOf((*MockMinerAPI)(nil).FetchUnsealedPiece), arg0, arg1, arg2)
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "FetchUnsealedPiece", reflect.TypeOf((*MockMinerAPI)(nil).FetchUnsealedPiece), arg0, arg1)
 }
 
 // GetUnpaddedCARSize mocks base method.
diff --git a/markets/dagstore/mount.go b/markets/dagstore/mount.go
index e4e6242d7..0ecdc9808 100644
--- a/markets/dagstore/mount.go
+++ b/markets/dagstore/mount.go
@@ -56,11 +56,7 @@ func (l *LotusMount) Deserialize(u *url.URL) error {
 }
 
 func (l *LotusMount) Fetch(ctx context.Context) (mount.Reader, error) {
-	return (&pieceReader{
-		ctx:      ctx,
-		api:      l.API,
-		pieceCid: l.PieceCid,
-	}).init()
+	return l.API.FetchUnsealedPiece(ctx, l.PieceCid)
 }
 
 func (l *LotusMount) Info() mount.Info {
diff --git a/markets/dagstore/mount_test.go b/markets/dagstore/mount_test.go
index 820058786..d6ea54964 100644
--- a/markets/dagstore/mount_test.go
+++ b/markets/dagstore/mount_test.go
@@ -2,6 +2,7 @@ package dagstore
 
 import (
 	"context"
+	"io"
 	"io/ioutil"
 	"net/url"
 	"strings"
@@ -12,8 +13,6 @@ import (
 	"github.com/stretchr/testify/require"
 
 	"github.com/filecoin-project/dagstore/mount"
-	"github.com/filecoin-project/go-state-types/abi"
-
 	mock_dagstore "github.com/filecoin-project/lotus/markets/dagstore/mocks"
 )
 
@@ -30,8 +29,28 @@ func TestLotusMount(t *testing.T) {
 	mockLotusMountAPI := mock_dagstore.NewMockMinerAPI(mockCtrl)
 
 	mockLotusMountAPI.EXPECT().IsUnsealed(gomock.Any(), cid).Return(true, nil).Times(1)
-	mockLotusMountAPI.EXPECT().FetchUnsealedPiece(gomock.Any(), cid, uint64(0)).Return(ioutil.NopCloser(strings.NewReader("testing")), abi.UnpaddedPieceSize(7), nil).Times(1)
-	mockLotusMountAPI.EXPECT().FetchUnsealedPiece(gomock.Any(), cid, uint64(0)).Return(ioutil.NopCloser(strings.NewReader("testing")), abi.UnpaddedPieceSize(7), nil).Times(1)
+
+	mr1 := struct {
+		io.ReadCloser
+		io.ReaderAt
+		io.Seeker
+	}{
+		ReadCloser: ioutil.NopCloser(strings.NewReader("testing")),
+		ReaderAt:   nil,
+		Seeker:     nil,
+	}
+	mr2 := struct {
+		io.ReadCloser
+		io.ReaderAt
+		io.Seeker
+	}{
+		ReadCloser: ioutil.NopCloser(strings.NewReader("testing")),
+		ReaderAt:   nil,
+		Seeker:     nil,
+	}
+
+	mockLotusMountAPI.EXPECT().FetchUnsealedPiece(gomock.Any(), cid).Return(mr1, nil).Times(1)
+	mockLotusMountAPI.EXPECT().FetchUnsealedPiece(gomock.Any(), cid).Return(mr2, nil).Times(1)
 	mockLotusMountAPI.EXPECT().GetUnpaddedCARSize(ctx, cid).Return(uint64(100), nil).Times(1)
 
 	mnt, err := NewLotusMount(cid, mockLotusMountAPI)
diff --git a/markets/dagstore/wrapper_migration_test.go b/markets/dagstore/wrapper_migration_test.go
index 502105499..e46f8779b 100644
--- a/markets/dagstore/wrapper_migration_test.go
+++ b/markets/dagstore/wrapper_migration_test.go
@@ -6,9 +6,9 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/require"
-	"golang.org/x/xerrors"
 
 	"github.com/filecoin-project/dagstore"
+	"github.com/filecoin-project/dagstore/mount"
 	"github.com/filecoin-project/go-state-types/abi"
 
 	"github.com/filecoin-project/go-fil-markets/retrievalmarket"
@@ -127,17 +127,20 @@ type wrappedSA struct {
 	retrievalmarket.SectorAccessor
 }
 
-func (w *wrappedSA) UnsealSectorAt(ctx context.Context, sectorID abi.SectorNumber, pieceOffset abi.UnpaddedPieceSize, startOffset uint64, length abi.UnpaddedPieceSize) (io.ReadCloser, error) {
+func (w *wrappedSA) UnsealSectorAt(ctx context.Context, sectorID abi.SectorNumber, pieceOffset abi.UnpaddedPieceSize, length abi.UnpaddedPieceSize) (mount.Reader, error) {
 	r, err := w.UnsealSector(ctx, sectorID, pieceOffset, length)
 	if err != nil {
 		return nil, err
 	}
-	if startOffset > 0 {
-		if _, err := io.CopyN(io.Discard, r, int64(startOffset)); err != nil {
-			return nil, xerrors.Errorf("discard start off: %w", err)
-		}
-	}
-	return r, err
+	return struct {
+		io.ReadCloser
+		io.Seeker
+		io.ReaderAt
+	}{
+		ReadCloser: r,
+		Seeker:     nil,
+		ReaderAt:   nil,
+	}, err
 }
 
 var _ SectorAccessor = &wrappedSA{}
diff --git a/markets/dagstore/wrapper_test.go b/markets/dagstore/wrapper_test.go
index a4a6215e1..48e01100b 100644
--- a/markets/dagstore/wrapper_test.go
+++ b/markets/dagstore/wrapper_test.go
@@ -3,7 +3,6 @@ package dagstore
 import (
 	"bytes"
 	"context"
-	"io"
 	"os"
 	"testing"
 	"time"
@@ -12,8 +11,6 @@ import (
 	"github.com/stretchr/testify/require"
 	"golang.org/x/xerrors"
 
-	"github.com/filecoin-project/go-state-types/abi"
-
 	"github.com/filecoin-project/dagstore"
 	"github.com/filecoin-project/dagstore/mount"
 	"github.com/filecoin-project/dagstore/shard"
@@ -192,7 +189,7 @@ func (m mockLotusMount) Start(ctx context.Context) error {
 	return nil
 }
 
-func (m mockLotusMount) FetchUnsealedPiece(ctx context.Context, pieceCid cid.Cid, offset uint64) (io.ReadCloser, abi.UnpaddedPieceSize, error) {
+func (m mockLotusMount) FetchUnsealedPiece(context.Context, cid.Cid) (mount.Reader, error) {
 	panic("implement me")
 }
 
diff --git a/markets/sectoraccessor/sectoraccessor.go b/markets/sectoraccessor/sectoraccessor.go
index f70aca103..4320e3fb1 100644
--- a/markets/sectoraccessor/sectoraccessor.go
+++ b/markets/sectoraccessor/sectoraccessor.go
@@ -4,8 +4,16 @@ import (
 	"context"
 	"io"
 
+	"github.com/ipfs/go-cid"
+	logging "github.com/ipfs/go-log/v2"
 	"golang.org/x/xerrors"
 
+	"github.com/filecoin-project/dagstore/mount"
+	"github.com/filecoin-project/go-address"
+	"github.com/filecoin-project/go-fil-markets/retrievalmarket"
+	"github.com/filecoin-project/go-state-types/abi"
+	specstorage "github.com/filecoin-project/specs-storage/storage"
+
 	"github.com/filecoin-project/lotus/api"
 	"github.com/filecoin-project/lotus/api/v1api"
 	"github.com/filecoin-project/lotus/chain/types"
@@ -14,14 +22,6 @@ import (
 	"github.com/filecoin-project/lotus/markets/dagstore"
 	"github.com/filecoin-project/lotus/node/modules/dtypes"
 	"github.com/filecoin-project/lotus/storage/sectorblocks"
-
-	"github.com/filecoin-project/go-address"
-	"github.com/filecoin-project/go-fil-markets/retrievalmarket"
-	"github.com/filecoin-project/go-state-types/abi"
-	specstorage "github.com/filecoin-project/specs-storage/storage"
-
-	"github.com/ipfs/go-cid"
-	logging "github.com/ipfs/go-log/v2"
 )
 
 var log = logging.Logger("sectoraccessor")
@@ -40,10 +40,10 @@ func NewSectorAccessor(maddr dtypes.MinerAddress, secb sectorblocks.SectorBuilde
 }
 
 func (sa *sectorAccessor) UnsealSector(ctx context.Context, sectorID abi.SectorNumber, pieceOffset abi.UnpaddedPieceSize, length abi.UnpaddedPieceSize) (io.ReadCloser, error) {
-	return sa.UnsealSectorAt(ctx, sectorID, pieceOffset, 0, length)
+	return sa.UnsealSectorAt(ctx, sectorID, pieceOffset, length)
 }
 
-func (sa *sectorAccessor) UnsealSectorAt(ctx context.Context, sectorID abi.SectorNumber, pieceOffset abi.UnpaddedPieceSize, startOffset uint64, length abi.UnpaddedPieceSize) (io.ReadCloser, error) {
+func (sa *sectorAccessor) UnsealSectorAt(ctx context.Context, sectorID abi.SectorNumber, pieceOffset abi.UnpaddedPieceSize, length abi.UnpaddedPieceSize) (mount.Reader, error) {
 	log.Debugf("get sector %d, pieceOffset %d, length %d", sectorID, pieceOffset, length)
 	si, err := sa.sectorsStatus(ctx, sectorID, false)
 	if err != nil {
@@ -69,8 +69,8 @@ func (sa *sectorAccessor) UnsealSectorAt(ctx context.Context, sectorID abi.Secto
 	}
 
 	// Get a reader for the piece, unsealing the piece if necessary
-	log.Debugf("read piece in sector %d, pieceOffset %d, startOffset %d, length %d from miner %d", sectorID, pieceOffset, startOffset, length, mid)
-	r, unsealed, err := sa.pp.ReadPiece(ctx, ref, storiface.UnpaddedByteIndex(pieceOffset), startOffset, length, si.Ticket.Value, commD)
+	log.Debugf("read piece in sector %d, pieceOffset %d, length %d from miner %d", sectorID, pieceOffset, length, mid)
+	r, unsealed, err := sa.pp.ReadPiece(ctx, ref, storiface.UnpaddedByteIndex(pieceOffset), length, si.Ticket.Value, commD)
 	if err != nil {
 		return nil, xerrors.Errorf("failed to unseal piece from sector %d: %w", sectorID, err)
 	}
diff --git a/testplans/lotus-soup/go.sum b/testplans/lotus-soup/go.sum
index 905c9d924..d27b270f8 100644
--- a/testplans/lotus-soup/go.sum
+++ b/testplans/lotus-soup/go.sum
@@ -995,8 +995,9 @@ github.com/ipfs/go-ipld-format v0.0.1/go.mod h1:kyJtbkDALmFHv3QR6et67i35QzO3S0dC
 github.com/ipfs/go-ipld-format v0.0.2/go.mod h1:4B6+FM2u9OJ9zCV+kSbgFAZlOrv1Hqbf0INGQgiKf9k=
 github.com/ipfs/go-ipld-format v0.2.0 h1:xGlJKkArkmBvowr+GMCX0FEZtkro71K1AwiKnL37mwA=
 github.com/ipfs/go-ipld-format v0.2.0/go.mod h1:3l3C1uKoadTPbeNfrDi+xMInYKlx2Cvg1BuydPSdzQs=
-github.com/ipfs/go-ipld-legacy v0.1.0 h1:wxkkc4k8cnvIGIjPO0waJCe7SHEyFgl+yQdafdjGrpA=
 github.com/ipfs/go-ipld-legacy v0.1.0/go.mod h1:86f5P/srAmh9GcIcWQR9lfFLZPrIyyXQeVlOWeeWEuI=
+github.com/ipfs/go-ipld-legacy v0.1.1 h1:BvD8PEuqwBHLTKqlGFTHSwrwFOMkVESEvwIYwR2cdcc=
+github.com/ipfs/go-ipld-legacy v0.1.1/go.mod h1:8AyKFCjgRPsQFf15ZQgDB8Din4DML/fOmKZkkFkrIEg=
 github.com/ipfs/go-ipns v0.1.2 h1:O/s/0ht+4Jl9+VoxoUo0zaHjnZUS+aBQIKTuzdZ/ucI=
 github.com/ipfs/go-ipns v0.1.2/go.mod h1:ioQ0j02o6jdIVW+bmi18f4k2gRf0AV3kZ9KeHYHICnQ=
 github.com/ipfs/go-log v0.0.1/go.mod h1:kL1d2/hzSpI0thNYjiKfjanbVNU+IIGA/WnNESY9leM=
@@ -2307,8 +2308,9 @@ golang.org/x/crypto v0.0.0-20210513164829-c07d793c2f9a/go.mod h1:P+XmwS30IXTQdn5
 golang.org/x/crypto v0.0.0-20210616213533-5ff15b29337e/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.0.0-20210711020723-a769d52b0f97/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
 golang.org/x/crypto v0.0.0-20210813211128-0a44fdfbc16e/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
-golang.org/x/crypto v0.0.0-20210915214749-c084706c2272 h1:3erb+vDS8lU1sxfDHF4/hhWyaXnhIaO+7RgL4fDZORA=
 golang.org/x/crypto v0.0.0-20210915214749-c084706c2272/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
+golang.org/x/crypto v0.0.0-20211209193657-4570a0811e8b h1:QAqMVf3pSa6eeTsuklijukjXBlj7Es2QQplab+/RbQ4=
+golang.org/x/crypto v0.0.0-20211209193657-4570a0811e8b/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
 golang.org/x/exp v0.0.0-20180321215751-8460e604b9de/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20180807140117-3d87b88a115f/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
 golang.org/x/exp v0.0.0-20181106170214-d68db9428509/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
@@ -2425,8 +2427,9 @@ golang.org/x/net v0.0.0-20210428140749-89ef3d95e781/go.mod h1:OJAsFXCWl8Ukc7SiCT
 golang.org/x/net v0.0.0-20210525063256-abc453219eb5/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20210614182718-04defd469f4e/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/net v0.0.0-20210813160813-60bc85c4be6d/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
-golang.org/x/net v0.0.0-20210917221730-978cfadd31cf h1:R150MpwJIv1MpS0N/pc+NhTM8ajzvlmxlY5OYsrevXQ=
 golang.org/x/net v0.0.0-20210917221730-978cfadd31cf/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
+golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2 h1:CIJ76btIcR3eFI5EgSo6k1qKw9KJexJuRLI9G7Hp5wE=
+golang.org/x/net v0.0.0-20211112202133-69e39bad7dc2/go.mod h1:9nx3DQGgdP8bBQD5qxJ1jj9UTztislL4KSBs9R2vV5Y=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20181017192945-9dcd33a902f4/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20181203162652-d668ce993890/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
@@ -2566,8 +2569,8 @@ golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.0.0-20210816183151-1e6c022a8912/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210823070655-63515b42dcdf/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210917161153-d61c044b1678/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20211007075335-d3039528d8ac h1:oN6lz7iLW/YC7un8pq+9bOLyXrprv2+DKfkJY+2LJJw=
-golang.org/x/sys v0.0.0-20211007075335-d3039528d8ac/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20211209171907-798191bca915 h1:P+8mCzuEpyszAT6T42q0sxU+eveBAF/cJ2Kp0x6/8+0=
+golang.org/x/sys v0.0.0-20211209171907-798191bca915/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201117132131-f5c789dd3221/go.mod h1:Nr5EML6q2oocZ2LXRh80K7BxOlk5/8JxuGnuhpl+muw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20201210144234-2321bbc49cbf h1:MZ2shdL+ZM/XzY3ZGOnh4Nlpnxz5GSOhOmtHo3iPU6M=
@@ -2859,8 +2862,9 @@ k8s.io/klog/v2 v2.0.0/go.mod h1:PBfzABfn139FHAV07az/IF9Wp1bkk3vpT2XSJ76fSDE=
 k8s.io/kube-openapi v0.0.0-20200316234421-82d701f24f9d/go.mod h1:F+5wygcW0wmRTnM3cOgIqGivxkwSWIWT5YdsDbeAOaU=
 k8s.io/utils v0.0.0-20191114184206-e782cd3c129f/go.mod h1:sZAwmy6armz5eXlNoLmJcl4F1QuKu7sr+mFQ0byX7Ew=
 k8s.io/utils v0.0.0-20200414100711-2df71ebbae66/go.mod h1:jPW/WVKK9YHAvNhRxK0md/EJ228hCsBRufyofKtW8HA=
-lukechampine.com/blake3 v1.1.6 h1:H3cROdztr7RCfoaTpGZFQsrqvweFLrqS73j7L7cmR5c=
 lukechampine.com/blake3 v1.1.6/go.mod h1:tkKEOtDkNtklkXtLNEOGNq5tcV90tJiA1vAA12R78LA=
+lukechampine.com/blake3 v1.1.7 h1:GgRMhmdsuK8+ii6UZFDL8Nb+VyMwadAgcJyfYHxG6n0=
+lukechampine.com/blake3 v1.1.7/go.mod h1:tkKEOtDkNtklkXtLNEOGNq5tcV90tJiA1vAA12R78LA=
 modernc.org/cc v1.0.0 h1:nPibNuDEx6tvYrUAtvDTTw98rx5juGsa5zuDnKwEEQQ=
 modernc.org/cc v1.0.0/go.mod h1:1Sk4//wdnYJiUIxnW8ddKpaOJCF37yAdqYnkxUpaYxw=
 modernc.org/fileutil v1.0.0/go.mod h1:JHsWpkrk/CnVV1H/eGlFf85BEpfkrp56ro8nojIq9Q8=