diff --git a/chain/store/store.go b/chain/store/store.go
index 4dabb96f7..f2ebf2b41 100644
--- a/chain/store/store.go
+++ b/chain/store/store.go
@@ -20,6 +20,7 @@ import (
 	"github.com/filecoin-project/lotus/api"
 	"github.com/filecoin-project/lotus/chain/state"
 	"github.com/filecoin-project/lotus/chain/vm"
+	"github.com/filecoin-project/lotus/journal"
 	"github.com/filecoin-project/lotus/metrics"
 	"go.opencensus.io/stats"
 	"go.opencensus.io/trace"
@@ -324,6 +325,14 @@ func (cs *ChainStore) reorgWorker(ctx context.Context, initialNotifees []ReorgNo
 					continue
 				}
 
+				journal.Add("sync", map[string]interface{}{
+					"op":    "headChange",
+					"from":  r.old.Key(),
+					"to":    r.new.Key(),
+					"rev":   len(revert),
+					"apply": len(apply),
+				})
+
 				// reverse the apply array
 				for i := len(apply)/2 - 1; i >= 0; i-- {
 					opp := len(apply) - 1 - i
diff --git a/journal/journal.go b/journal/journal.go
new file mode 100644
index 000000000..b664e8fa7
--- /dev/null
+++ b/journal/journal.go
@@ -0,0 +1,146 @@
+package journal
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	logging "github.com/ipfs/go-log"
+	"golang.org/x/xerrors"
+)
+
+func InitializeSystemJournal(dir string) error {
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return err
+	}
+	j, err := OpenFSJournal(dir)
+	if err != nil {
+		return err
+	}
+	currentJournal = j
+	return nil
+}
+
+func Add(sys string, val interface{}) {
+	if currentJournal == nil {
+		log.Warn("no journal configured")
+		return
+	}
+	currentJournal.AddEntry(sys, val)
+}
+
+var log = logging.Logger("journal")
+
+var currentJournal Journal
+
+type Journal interface {
+	AddEntry(system string, obj interface{})
+	Close() error
+}
+
+// fsJournal is a basic journal backed by files on a filesystem
+type fsJournal struct {
+	fi    *os.File
+	fSize int64
+
+	lk sync.Mutex
+
+	journalDir string
+
+	incoming         chan *JournalEntry
+	journalSizeLimit int64
+
+	closing chan struct{}
+}
+
+func OpenFSJournal(dir string) (*fsJournal, error) {
+	fsj := &fsJournal{
+		journalDir:       dir,
+		incoming:         make(chan *JournalEntry, 32),
+		journalSizeLimit: 1 << 30,
+		closing:          make(chan struct{}),
+	}
+
+	if err := fsj.rollJournalFile(); err != nil {
+		return nil, err
+	}
+
+	go fsj.runLoop()
+
+	return fsj, nil
+}
+
+type JournalEntry struct {
+	System    string
+	Timestamp time.Time
+	Val       interface{}
+}
+
+func (fsj *fsJournal) putEntry(je *JournalEntry) error {
+	b, err := json.Marshal(je)
+	if err != nil {
+		return err
+	}
+	n, err := fsj.fi.Write(append(b, '\n'))
+	if err != nil {
+		return err
+	}
+
+	fsj.fSize += int64(n)
+
+	if fsj.fSize >= fsj.journalSizeLimit {
+		fsj.rollJournalFile()
+	}
+
+	return nil
+}
+
+func (fsj *fsJournal) rollJournalFile() error {
+	if fsj.fi != nil {
+		fsj.fi.Close()
+	}
+
+	nfi, err := os.Create(filepath.Join(fsj.journalDir, fmt.Sprintf("lotus-journal-%s.ndjson", time.Now().Format(time.RFC3339))))
+	if err != nil {
+		return xerrors.Errorf("failed to open journal file: %w", err)
+	}
+
+	fsj.fi = nfi
+	fsj.fSize = 0
+	return nil
+}
+
+func (fsj *fsJournal) runLoop() {
+	for {
+		select {
+		case je := <-fsj.incoming:
+			if err := fsj.putEntry(je); err != nil {
+				log.Errorw("failed to write out journal entry", "entry", je, "err", err)
+			}
+		case <-fsj.closing:
+			fsj.fi.Close()
+			return
+		}
+	}
+}
+
+func (fsj *fsJournal) AddEntry(system string, obj interface{}) {
+	je := &JournalEntry{
+		System:    system,
+		Timestamp: time.Now(),
+		Val:       obj,
+	}
+	select {
+	case fsj.incoming <- je:
+	case <-fsj.closing:
+		log.Warnw("journal closed but tried to log event", "entry", je)
+	}
+}
+
+func (fsj *fsJournal) Close() error {
+	close(fsj.closing)
+	return nil
+}
diff --git a/node/builder.go b/node/builder.go
index 2ffe88921..5246028e7 100644
--- a/node/builder.go
+++ b/node/builder.go
@@ -119,6 +119,7 @@ const (
 	ExtractApiKey
 	HeadMetricsKey
 	RunPeerTaggerKey
+	JournalKey
 
 	SetApiEndpointKey
 
@@ -150,6 +151,7 @@ func defaults() []Option {
 		Override(new(record.Validator), modules.RecordValidator),
 		Override(new(dtypes.Bootstrapper), dtypes.Bootstrapper(false)),
 		Override(new(dtypes.ShutdownChan), make(chan struct{})),
+		Override(JournalKey, modules.SetupJournal),
 
 		// Filecoin modules
 
diff --git a/node/modules/core.go b/node/modules/core.go
index ca9872d90..84179bd63 100644
--- a/node/modules/core.go
+++ b/node/modules/core.go
@@ -6,6 +6,7 @@ import (
 	"errors"
 	"io"
 	"io/ioutil"
+	"path/filepath"
 
 	"github.com/gbrlsnchs/jwt/v3"
 	logging "github.com/ipfs/go-log/v2"
@@ -18,6 +19,7 @@ import (
 	"github.com/filecoin-project/lotus/api/apistruct"
 	"github.com/filecoin-project/lotus/build"
 	"github.com/filecoin-project/lotus/chain/types"
+	"github.com/filecoin-project/lotus/journal"
 	"github.com/filecoin-project/lotus/lib/addrutil"
 	"github.com/filecoin-project/lotus/node/modules/dtypes"
 	"github.com/filecoin-project/lotus/node/repo"
@@ -93,3 +95,7 @@ func BuiltinBootstrap() (dtypes.BootstrapPeers, error) {
 func DrandBootstrap() (dtypes.DrandBootstrap, error) {
 	return build.DrandBootstrap()
 }
+
+func SetupJournal(lr repo.LockedRepo) error {
+	return journal.InitializeSystemJournal(filepath.Join(lr.Path(), "journal"))
+}