diff --git a/pkg/blockstore/blockstore.go b/pkg/blockstore/blockstore.go
index 36cde7e4..4329624f 100644
--- a/pkg/blockstore/blockstore.go
+++ b/pkg/blockstore/blockstore.go
@@ -395,10 +395,11 @@ func (s *BlockStore) ReadAt(ctx context.Context, blockId string, name string, of
 			// limit read to the actual size of the file
 			size = entry.FileEntry.File.Size - offset
 		}
-		for partIdx, _ := range dataEntries {
-			if entry.DataEntries[partIdx] != nil {
-				dataEntries[partIdx] = entry.DataEntries[partIdx]
+		for _, partIdx := range partsNeeded {
+			if len(entry.DataEntries) <= partIdx || entry.DataEntries[partIdx] == nil {
+				continue
 			}
+			dataEntries[partIdx] = entry.DataEntries[partIdx]
 		}
 		return nil
 	})
@@ -428,6 +429,17 @@ func (s *BlockStore) ReadAt(ctx context.Context, blockId string, name string, of
 	return offset, rtn, nil
 }
 
+func (s *BlockStore) ReadFile(ctx context.Context, blockId string, name string) (int64, []byte, error) {
+	file, err := s.Stat(ctx, blockId, name)
+	if err != nil {
+		return 0, nil, fmt.Errorf("error getting file: %v", err)
+	}
+	if file == nil {
+		return 0, nil, fmt.Errorf("file not found")
+	}
+	return s.ReadAt(ctx, blockId, name, 0, file.Size)
+}
+
 func minInt64(a, b int64) int64 {
 	if a < b {
 		return a
diff --git a/pkg/blockstore/blockstore_cache.go b/pkg/blockstore/blockstore_cache.go
index 8b72fa5a..b9b85324 100644
--- a/pkg/blockstore/blockstore_cache.go
+++ b/pkg/blockstore/blockstore_cache.go
@@ -4,6 +4,7 @@
 package blockstore
 
 import (
+	"bytes"
 	"fmt"
 	"sync"
 	"sync/atomic"
@@ -43,6 +44,35 @@ type CacheEntry struct {
 	DataEntries []*DataCacheEntry
 }
 
+func (e *CacheEntry) dump() string {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "CacheEntry{\nBlockId: %q, Name: %q, Version: %d, PinCount: %d, Deleted: %v\n", e.BlockId, e.Name, e.Version, e.PinCount, e.Deleted)
+	if e.FileEntry != nil {
+		fmt.Fprintf(&buf, "FileEntry: %v\n", e.FileEntry.File)
+	}
+	for i, dce := range e.DataEntries {
+		if dce != nil {
+			fmt.Fprintf(&buf, "DataEntry[%d][%v]: %q\n", i, dce.Dirty.Load(), string(dce.Data))
+		}
+	}
+	buf.WriteString("}\n")
+	return buf.String()
+}
+
+func (s *BlockStore) dump() string {
+	s.Lock.Lock()
+	defer s.Lock.Unlock()
+	var buf bytes.Buffer
+	buf.WriteString(fmt.Sprintf("BlockStore %d entries\n", len(s.Cache)))
+	for _, v := range s.Cache {
+		entryStr := v.dump()
+		buf.WriteString(entryStr)
+		buf.WriteString("\n")
+	}
+	return buf.String()
+
+}
+
 // for testing
 func (s *BlockStore) getCacheSize() int {
 	s.Lock.Lock()
diff --git a/pkg/blockstore/blockstore_test.go b/pkg/blockstore/blockstore_test.go
index d963dd8c..bfdd80f1 100644
--- a/pkg/blockstore/blockstore_test.go
+++ b/pkg/blockstore/blockstore_test.go
@@ -132,3 +132,57 @@ func TestSetMeta(t *testing.T) {
 	}
 	checkMapsEqual(t, map[string]any{"a": 6, "b": "hello", "c": "world", "d": 7}, file.Meta, "meta")
 }
+
+func checkFileSize(t *testing.T, ctx context.Context, blockId string, name string, size int64) {
+	file, err := GBS.Stat(ctx, blockId, name)
+	if err != nil {
+		t.Errorf("error stating file %q: %v", name, err)
+		return
+	}
+	if file == nil {
+		t.Errorf("file %q not found", name)
+		return
+	}
+	if file.Size != size {
+		t.Errorf("size mismatch for file %q: expected %d, got %d", name, size, file.Size)
+	}
+}
+
+func checkFileData(t *testing.T, ctx context.Context, blockId string, name string, data string) {
+	_, rdata, err := GBS.ReadFile(ctx, blockId, name)
+	if err != nil {
+		t.Errorf("error reading data for file %q: %v", name, err)
+		return
+	}
+	if string(rdata) != data {
+		t.Errorf("data mismatch for file %q: expected %q, got %q", name, data, string(rdata))
+	}
+}
+
+func TestAppend(t *testing.T) {
+	initDb(t)
+	defer cleanupDb(t)
+
+	ctx, cancelFn := context.WithTimeout(context.Background(), 5*time.Second)
+	defer cancelFn()
+	blockId := uuid.New().String()
+	fileName := "t2"
+	err := GBS.MakeFile(ctx, blockId, fileName, nil, FileOptsType{})
+	if err != nil {
+		t.Fatalf("error creating file: %v", err)
+	}
+	err = GBS.AppendData(ctx, blockId, fileName, []byte("hello"))
+	if err != nil {
+		t.Fatalf("error appending data: %v", err)
+	}
+	// fmt.Print(GBS.dump())
+	checkFileSize(t, ctx, blockId, fileName, 5)
+	checkFileData(t, ctx, blockId, fileName, "hello")
+	err = GBS.AppendData(ctx, blockId, fileName, []byte(" world"))
+	if err != nil {
+		t.Fatalf("error appending data: %v", err)
+	}
+	// fmt.Print(GBS.dump())
+	checkFileSize(t, ctx, blockId, fileName, 11)
+	checkFileData(t, ctx, blockId, fileName, "hello world")
+}