diff --git a/ffiwrapper/partialfile.go b/ffiwrapper/partialfile.go
index a2c1f1151..8c4fdcc72 100644
--- a/ffiwrapper/partialfile.go
+++ b/ffiwrapper/partialfile.go
@@ -12,6 +12,7 @@ import (
 	rlepluslazy "github.com/filecoin-project/go-bitfield/rle"
 	"github.com/filecoin-project/specs-actors/actors/abi"
 
+	"github.com/filecoin-project/sector-storage/fsutil"
 	"github.com/filecoin-project/sector-storage/storiface"
 )
 
@@ -218,6 +219,28 @@ func (pf *partialFile) MarkAllocated(offset storiface.PaddedByteIndex, size abi.
 	return nil
 }
 
+func (pf *partialFile) Free(offset storiface.PaddedByteIndex, size abi.PaddedPieceSize) error {
+	have, err := pf.allocated.RunIterator()
+	if err != nil {
+		return err
+	}
+
+	if err := fsutil.Deallocate(pf.file, int64(offset), int64(size)); err != nil {
+		return xerrors.Errorf("deallocating: %w", err)
+	}
+
+	s, err := rlepluslazy.Subtract(have, pieceRun(offset, size))
+	if err != nil {
+		return err
+	}
+
+	if err := writeTrailer(int64(pf.maxPiece), pf.file, s); err != nil {
+		return xerrors.Errorf("writing trailer: %w", err)
+	}
+
+	return nil
+}
+
 func (pf *partialFile) Reader(offset storiface.PaddedByteIndex, size abi.PaddedPieceSize) (*os.File, error) {
 	if _, err := pf.file.Seek(int64(offset), io.SeekStart); err != nil {
 		return nil, xerrors.Errorf("seek piece start: %w", err)
diff --git a/ffiwrapper/sealer_cgo.go b/ffiwrapper/sealer_cgo.go
index 177ddeae0..58d9d8c5b 100644
--- a/ffiwrapper/sealer_cgo.go
+++ b/ffiwrapper/sealer_cgo.go
@@ -15,6 +15,7 @@ import (
 	"golang.org/x/xerrors"
 
 	ffi "github.com/filecoin-project/filecoin-ffi"
+	rlepluslazy "github.com/filecoin-project/go-bitfield/rle"
 	commcid "github.com/filecoin-project/go-fil-commcid"
 	"github.com/filecoin-project/specs-actors/actors/abi"
 	"github.com/filecoin-project/specs-storage/storage"
@@ -502,7 +503,60 @@ func (sb *Sealer) SealCommit2(ctx context.Context, sector abi.SectorID, phase1Ou
 
 func (sb *Sealer) FinalizeSector(ctx context.Context, sector abi.SectorID, keepUnsealed []storage.Range) error {
 	if len(keepUnsealed) > 0 {
-		return xerrors.Errorf("keepUnsealed unsupported") // TODO: impl for fastretrieval copies
+		maxPieceSize := abi.PaddedPieceSize(sb.ssize)
+
+		sr := pieceRun(0, maxPieceSize)
+
+		for _, s := range keepUnsealed {
+			si := &rlepluslazy.RunSliceIterator{}
+			if s.Offset != 0 {
+				si.Runs = append(si.Runs, rlepluslazy.Run{Val: false, Len: uint64(s.Offset)})
+			}
+			si.Runs = append(si.Runs, rlepluslazy.Run{Val: true, Len: uint64(s.Size)})
+
+			var err error
+			sr, err = rlepluslazy.Subtract(sr, si)
+			if err != nil {
+				return err
+			}
+		}
+
+
+		paths, done, err := sb.sectors.AcquireSector(ctx, sector, stores.FTUnsealed, 0, false)
+		if err != nil {
+			return xerrors.Errorf("acquiring sector cache path: %w", err)
+		}
+		defer done()
+
+		pf, err := openPartialFile(maxPieceSize, paths.Unsealed)
+		if xerrors.Is(err, os.ErrNotExist) {
+			return xerrors.Errorf("opening partial file: %w", err)
+		}
+
+		var at uint64
+		for sr.HasNext() {
+			r, err := sr.NextRun()
+			if err != nil {
+				_ = pf.Close()
+				return err
+			}
+
+			offset := at
+			at += r.Len
+			if !r.Val {
+				continue
+			}
+
+			err = pf.Free(storiface.PaddedByteIndex(abi.UnpaddedPieceSize(offset).Padded()), abi.UnpaddedPieceSize(r.Len).Padded())
+			if err != nil {
+				_ = pf.Close()
+				return xerrors.Errorf("free partial file range: %w", err)
+			}
+		}
+
+		if err := pf.Close(); err != nil {
+			return err
+		}
 	}
 
 	paths, done, err := sb.sectors.AcquireSector(ctx, sector, stores.FTCache, 0, false)
diff --git a/fsutil/dealloc_linux.go b/fsutil/dealloc_linux.go
new file mode 100644
index 000000000..0b20c568d
--- /dev/null
+++ b/fsutil/dealloc_linux.go
@@ -0,0 +1,28 @@
+package fsutil
+
+import (
+	"os"
+	"syscall"
+
+	logging "github.com/ipfs/go-log/v2"
+)
+
+var log = logging.Logger("fsutil")
+
+const FallocFlPunchHole = 0x02 // linux/falloc.h
+
+func Deallocate(file *os.File, offset int64, length int64) error {
+	if length == 0 {
+		return nil
+	}
+
+	err := syscall.Fallocate(int(file.Fd()), FallocFlPunchHole, offset, length)
+	if errno, ok := err.(syscall.Errno); ok {
+		if errno == syscall.EOPNOTSUPP || errno == syscall.ENOSYS {
+			log.Warnf("could not deallocate space, ignoring: %v", errno)
+			err = nil // log and ignore
+		}
+	}
+
+	return err
+}
diff --git a/fsutil/dealloc_other.go b/fsutil/dealloc_other.go
new file mode 100644
index 000000000..721116af1
--- /dev/null
+++ b/fsutil/dealloc_other.go
@@ -0,0 +1,18 @@
+// +build !linux
+
+package fsutil
+
+import (
+	"os"
+
+	logging "github.com/ipfs/go-log/v2"
+)
+
+var log = logging.Logger("fsutil")
+
+
+func Deallocate(file *os.File, offset int64, length int64) error {
+	log.Warnf("deallocating space not supported")
+
+	return err
+}
diff --git a/go.mod b/go.mod
index 9e51c0445..83424841f 100644
--- a/go.mod
+++ b/go.mod
@@ -6,7 +6,7 @@ require (
 	github.com/detailyang/go-fallocate v0.0.0-20180908115635-432fa640bd2e
 	github.com/elastic/go-sysinfo v1.3.0
 	github.com/filecoin-project/filecoin-ffi v0.0.0-20200326153646-e899cc1dd072
-	github.com/filecoin-project/go-bitfield v0.0.2-0.20200518150651-562fdb554b6e
+	github.com/filecoin-project/go-bitfield v0.0.4-0.20200703174658-f4a5758051a1
 	github.com/filecoin-project/go-fil-commcid v0.0.0-20200208005934-2b8bd03caca5
 	github.com/filecoin-project/go-paramfetch v0.0.1
 	github.com/filecoin-project/specs-actors v0.6.1
diff --git a/go.sum b/go.sum
index 2f97216e3..330b97579 100644
--- a/go.sum
+++ b/go.sum
@@ -36,6 +36,8 @@ github.com/filecoin-project/go-bitfield v0.0.1 h1:Xg/JnrqqE77aJVKdbEyR04n9FZQWhw
 github.com/filecoin-project/go-bitfield v0.0.1/go.mod h1:Ry9/iUlWSyjPUzlAvdnfy4Gtvrq4kWmWDztCU1yEgJY=
 github.com/filecoin-project/go-bitfield v0.0.2-0.20200518150651-562fdb554b6e h1:gkG/7G+iKy4He+IiQNeQn+nndFznb/vCoOR8iRQsm60=
 github.com/filecoin-project/go-bitfield v0.0.2-0.20200518150651-562fdb554b6e/go.mod h1:Ry9/iUlWSyjPUzlAvdnfy4Gtvrq4kWmWDztCU1yEgJY=
+github.com/filecoin-project/go-bitfield v0.0.4-0.20200703174658-f4a5758051a1 h1:xuHlrdznafh7ul5t4xEncnA4qgpQvJZEw+mr98eqHXw=
+github.com/filecoin-project/go-bitfield v0.0.4-0.20200703174658-f4a5758051a1/go.mod h1:Ry9/iUlWSyjPUzlAvdnfy4Gtvrq4kWmWDztCU1yEgJY=
 github.com/filecoin-project/go-crypto v0.0.0-20191218222705-effae4ea9f03 h1:2pMXdBnCiXjfCYx/hLqFxccPoqsSveQFxVLvNxy9bus=
 github.com/filecoin-project/go-crypto v0.0.0-20191218222705-effae4ea9f03/go.mod h1:+viYnvGtUTgJRdy6oaeF4MTFKAfatX071MPDPBL11EQ=
 github.com/filecoin-project/go-fil-commcid v0.0.0-20200208005934-2b8bd03caca5 h1:yvQJCW9mmi9zy+51xA01Ea2X7/dL7r8eKDPuGUjRmbo=
diff --git a/localworker.go b/localworker.go
index a1d82209a..a6042826a 100644
--- a/localworker.go
+++ b/localworker.go
@@ -171,8 +171,10 @@ func (l *LocalWorker) FinalizeSector(ctx context.Context, sector abi.SectorID, k
 		return xerrors.Errorf("finalizing sector: %w", err)
 	}
 
-	if err := l.storage.Remove(ctx, sector, stores.FTUnsealed, true); err != nil {
-		return xerrors.Errorf("removing unsealed data: %w", err)
+	if len(keepUnsealed) == 0 {
+		if err := l.storage.Remove(ctx, sector, stores.FTUnsealed, true); err != nil {
+			return xerrors.Errorf("removing unsealed data: %w", err)
+		}
 	}
 
 	return nil