InsertChunks for CAS store (#55)

- Improvement: Add batching when writing multiple small chunks to block store - decreases I/O load significantly on oplog import

15 files changed, 654 insertions, 177 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b70485a8c..92849ab44 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,6 +28,7 @@
 - Improvement: Add disk buffering in http client (improves download speed for oplog import)
 - Improvement: Add block hash verification for blocks received at oplog import
 - Improvement: Offload block decoding and chunk writing form network worker pool threads (improves download speed for oplog import)
+- Improvement: Add batching when writing multiple small chunks to block store - decreases I/O load significantly on oplog import
 
 ## 5.4.4
 - Bugfix: Get raw size for compressed chunks correctly for `/prj/{project}/oplog/{log}/chunkinfos`
diff --git a/src/zenserver-test/zenserver-test.cpp b/src/zenserver-test/zenserver-test.cpp
index 4d2c507fe..ccea53942 100644
--- a/src/zenserver-test/zenserver-test.cpp
+++ b/src/zenserver-test/zenserver-test.cpp
@@ -2873,6 +2873,10 @@ TEST_CASE("project.remote")
 		CHECK(IsHttpSuccessCode(Response.status_code));
 		CbPackage ResponsePackage = ParsePackageMessage(IoBuffer(IoBuffer::Wrap, Response.text.data(), Response.text.size()));
 		CHECK(ResponsePackage.GetAttachments().size() == AttachmentHashes.size());
+		for (auto A : ResponsePackage.GetAttachments())
+		{
+			CHECK(IoHash::HashBuffer(A.AsCompressedBinary().DecompressToComposite()) == A.GetHash());
+		}
 	};
 
 	auto ValidateOplog = [&SourceOps, &AddOp, &Servers, &Session](int ServerIndex, std::string_view Project, std::string_view Oplog) {
diff --git a/src/zenserver/cache/httpstructuredcache.cpp b/src/zenserver/cache/httpstructuredcache.cpp
index f64b9c5a5..8106e9db9 100644
--- a/src/zenserver/cache/httpstructuredcache.cpp
+++ b/src/zenserver/cache/httpstructuredcache.cpp
@@ -848,17 +848,20 @@ HttpStructuredCacheService::HandleGetCacheRecord(HttpServerRequest& Request, con
 				CbPackage Package;
 				if (Package.TryLoad(ClientResultValue.Value))
 				{
-					CbObject						 CacheRecord = Package.GetObject();
-					AttachmentCount					 Count;
-					size_t							 NumAttachments = Package.GetAttachments().size();
-					std::vector<const CbAttachment*> AttachmentsToStoreLocally;
-					std::vector<IoHash>				 ReferencedAttachments;
-					AttachmentsToStoreLocally.reserve(NumAttachments);
+					CbObject			  CacheRecord = Package.GetObject();
+					AttachmentCount		  Count;
+					size_t				  NumAttachments = Package.GetAttachments().size();
+					std::vector<IoHash>	  ReferencedAttachments;
+					std::vector<IoBuffer> WriteAttachmentBuffers;
+					WriteAttachmentBuffers.reserve(NumAttachments);
+					std::vector<IoHash> WriteRawHashes;
+					WriteRawHashes.reserve(NumAttachments);
 
 					CacheRecord.IterateAttachments([this,
 													&Package,
 													&Ref,
-													&AttachmentsToStoreLocally,
+													&WriteAttachmentBuffers,
+													&WriteRawHashes,
 													&ReferencedAttachments,
 													&Count,
 													QueryLocal,
@@ -872,7 +875,9 @@ HttpStructuredCacheService::HandleGetCacheRecord(HttpServerRequest& Request, con
 							{
 								if (StoreLocal)
 								{
-									AttachmentsToStoreLocally.emplace_back(Attachment);
+									CompressedBuffer Chunk = Attachment->AsCompressedBinary();
+									WriteAttachmentBuffers.push_back(Chunk.GetCompressed().Flatten().AsIoBuffer());
+									WriteRawHashes.push_back(Attachment->GetHash());
 								}
 								Count.Valid++;
 							}
@@ -923,18 +928,22 @@ HttpStructuredCacheService::HandleGetCacheRecord(HttpServerRequest& Request, con
 							m_CacheStore
 								.Put(RequestContext, Ref.Namespace, Ref.BucketSegment, Ref.HashKey, CacheValue, ReferencedAttachments);
 							m_CacheStats.WriteCount++;
-						}
 
-						for (const CbAttachment* Attachment : AttachmentsToStoreLocally)
-						{
-							ZEN_ASSERT_SLOW(StoreLocal);
-							CompressedBuffer	   Chunk = Attachment->AsCompressedBinary();
-							CidStore::InsertResult InsertResult =
-								m_CidStore.AddChunk(Chunk.GetCompressed().Flatten().AsIoBuffer(), Attachment->GetHash());
-							if (InsertResult.New)
+							if (!WriteAttachmentBuffers.empty())
 							{
-								Count.New++;
+								std::vector<CidStore::InsertResult> InsertResults =
+									m_CidStore.AddChunks(WriteAttachmentBuffers, WriteRawHashes);
+								for (const CidStore::InsertResult& Result : InsertResults)
+								{
+									if (Result.New)
+									{
+										Count.New++;
+									}
+								}
 							}
+
+							WriteAttachmentBuffers = {};
+							WriteRawHashes		   = {};
 						}
 
 						BinaryWriter MemStream;
@@ -1151,23 +1160,27 @@ HttpStructuredCacheService::HandlePutCacheRecord(HttpServerRequest& Request, con
 
 		CbObject CacheRecord = Package.GetObject();
 
-		AttachmentCount					 Count;
-		size_t							 NumAttachments = Package.GetAttachments().size();
-		std::vector<IoHash>				 ValidAttachments;
-		std::vector<IoHash>				 ReferencedAttachments;
-		std::vector<const CbAttachment*> AttachmentsToStoreLocally;
+		AttachmentCount		Count;
+		size_t				NumAttachments = Package.GetAttachments().size();
+		std::vector<IoHash> ValidAttachments;
+		std::vector<IoHash> ReferencedAttachments;
 		ValidAttachments.reserve(NumAttachments);
-		AttachmentsToStoreLocally.reserve(NumAttachments);
+		std::vector<IoBuffer> WriteAttachmentBuffers;
+		std::vector<IoHash>	  WriteRawHashes;
+		WriteAttachmentBuffers.reserve(NumAttachments);
+		WriteRawHashes.reserve(NumAttachments);
 
 		CacheRecord.IterateAttachments(
-			[this, &Ref, &Package, &AttachmentsToStoreLocally, &ValidAttachments, &ReferencedAttachments, &Count](CbFieldView HashView) {
+			[this, &Ref, &Package, &WriteAttachmentBuffers, &WriteRawHashes, &ValidAttachments, &ReferencedAttachments, &Count](
+				CbFieldView HashView) {
 				const IoHash Hash = HashView.AsHash();
 				ReferencedAttachments.push_back(Hash);
 				if (const CbAttachment* Attachment = Package.FindAttachment(Hash))
 				{
 					if (Attachment->IsCompressedBinary())
 					{
-						AttachmentsToStoreLocally.emplace_back(Attachment);
+						WriteAttachmentBuffers.emplace_back(Attachment->AsCompressedBinary().GetCompressed().Flatten().AsIoBuffer());
+						WriteRawHashes.push_back(Hash);
 						ValidAttachments.emplace_back(Hash);
 						Count.Valid++;
 					}
@@ -1202,14 +1215,18 @@ HttpStructuredCacheService::HandlePutCacheRecord(HttpServerRequest& Request, con
 		m_CacheStore.Put(RequestContext, Ref.Namespace, Ref.BucketSegment, Ref.HashKey, CacheValue, ReferencedAttachments);
 		m_CacheStats.WriteCount++;
 
-		for (const CbAttachment* Attachment : AttachmentsToStoreLocally)
+		if (!WriteAttachmentBuffers.empty())
 		{
-			CompressedBuffer	   Chunk		= Attachment->AsCompressedBinary();
-			CidStore::InsertResult InsertResult = m_CidStore.AddChunk(Chunk.GetCompressed().Flatten().AsIoBuffer(), Attachment->GetHash());
-			if (InsertResult.New)
+			std::vector<CidStore::InsertResult> InsertResults = m_CidStore.AddChunks(WriteAttachmentBuffers, WriteRawHashes);
+			for (const CidStore::InsertResult& InsertResult : InsertResults)
 			{
-				Count.New++;
+				if (InsertResult.New)
+				{
+					Count.New++;
+				}
 			}
+			WriteAttachmentBuffers = {};
+			WriteRawHashes		   = {};
 		}
 
 		ZEN_DEBUG("PUTCACHERECORD - '{}/{}/{}' {} '{}', attachments '{}/{}/{}' (new/valid/total) in {}",
diff --git a/src/zenserver/projectstore/projectstore.cpp b/src/zenserver/projectstore/projectstore.cpp
index 3a7922aaf..3c281275e 100644
--- a/src/zenserver/projectstore/projectstore.cpp
+++ b/src/zenserver/projectstore/projectstore.cpp
@@ -1448,19 +1448,36 @@ ProjectStore::Oplog::AppendNewOplogEntry(CbPackage OpPackage)
 
 	auto Attachments = OpPackage.GetAttachments();
 
-	for (const auto& Attach : Attachments)
+	if (!Attachments.empty())
 	{
-		ZEN_ASSERT(Attach.IsCompressedBinary());
+		std::vector<IoBuffer> WriteAttachmentBuffers;
+		std::vector<IoHash>	  WriteRawHashes;
+		std::vector<uint64_t> WriteRawSizes;
 
-		CompressedBuffer	   AttachmentData = Attach.AsCompressedBinary();
-		const uint64_t		   AttachmentSize = AttachmentData.DecodeRawSize();
-		CidStore::InsertResult InsertResult = m_CidStore.AddChunk(AttachmentData.GetCompressed().Flatten().AsIoBuffer(), Attach.GetHash());
+		WriteAttachmentBuffers.reserve(Attachments.size());
+		WriteRawHashes.reserve(Attachments.size());
+		WriteRawSizes.reserve(Attachments.size());
 
-		if (InsertResult.New)
+		for (const auto& Attach : Attachments)
 		{
-			NewAttachmentBytes += AttachmentSize;
+			ZEN_ASSERT(Attach.IsCompressedBinary());
+
+			CompressedBuffer AttachmentData = Attach.AsCompressedBinary();
+			const uint64_t	 AttachmentSize = AttachmentData.DecodeRawSize();
+			WriteAttachmentBuffers.push_back(AttachmentData.GetCompressed().Flatten().AsIoBuffer());
+			WriteRawHashes.push_back(Attach.GetHash());
+			WriteRawSizes.push_back(AttachmentSize);
+			AttachmentBytes += AttachmentSize;
+		}
+
+		std::vector<CidStore::InsertResult> InsertResults = m_CidStore.AddChunks(WriteAttachmentBuffers, WriteRawHashes);
+		for (size_t Index = 0; Index < InsertResults.size(); Index++)
+		{
+			if (InsertResults[Index].New)
+			{
+				NewAttachmentBytes += WriteRawSizes[Index];
+			}
 		}
-		AttachmentBytes += AttachmentSize;
 	}
 
 	ZEN_DEBUG("oplog entry #{} attachments: {} new, {} total", EntryId, NiceBytes(NewAttachmentBytes), NiceBytes(AttachmentBytes));
@@ -3354,12 +3371,25 @@ ProjectStore::Rpc(HttpServerRequest&	 HttpReq,
 			HttpReq.WriteResponse(HttpResponseCode::InsufficientStorage);
 			return true;
 		}
+
 		std::span<const CbAttachment> Attachments = Package.GetAttachments();
-		for (const CbAttachment& Attachment : Attachments)
+		if (!Attachments.empty())
 		{
-			IoHash			 RawHash	= Attachment.GetHash();
-			CompressedBuffer Compressed = Attachment.AsCompressedBinary();
-			m_CidStore.AddChunk(Compressed.GetCompressed().Flatten().AsIoBuffer(), RawHash, CidStore::InsertMode::kCopyOnly);
+			std::vector<IoBuffer> WriteAttachmentBuffers;
+			std::vector<IoHash>	  WriteRawHashes;
+
+			WriteAttachmentBuffers.reserve(Attachments.size());
+			WriteRawHashes.reserve(Attachments.size());
+
+			for (const CbAttachment& Attachment : Attachments)
+			{
+				IoHash			 RawHash	= Attachment.GetHash();
+				CompressedBuffer Compressed = Attachment.AsCompressedBinary();
+				WriteAttachmentBuffers.push_back(Compressed.GetCompressed().Flatten().AsIoBuffer());
+				WriteRawHashes.push_back(RawHash);
+			}
+
+			m_CidStore.AddChunks(WriteAttachmentBuffers, WriteRawHashes, CidStore::InsertMode::kCopyOnly);
 		}
 		HttpReq.WriteResponse(HttpResponseCode::OK);
 		return true;
@@ -4703,9 +4733,8 @@ TEST_CASE("project.store.block")
 											return CompositeBuffer(SharedBuffer(Buffer));
 										}));
 	}
-	CompressedBuffer Block		 = GenerateBlock(std::move(Chunks));
-	IoBuffer		 BlockBuffer = Block.GetCompressed().Flatten().AsIoBuffer();
-	CHECK(IterateBlock(Block.DecodeRawHash(), std::move(BlockBuffer), [](CompressedBuffer&&, const IoHash&) {}));
+	CompressedBuffer Block = GenerateBlock(std::move(Chunks));
+	CHECK(IterateBlock(Block.Decompress(), [](CompressedBuffer&&, const IoHash&) {}));
 }
 
 #endif
diff --git a/src/zenserver/projectstore/remoteprojectstore.cpp b/src/zenserver/projectstore/remoteprojectstore.cpp
index e9c6964c5..e922fcf1c 100644
--- a/src/zenserver/projectstore/remoteprojectstore.cpp
+++ b/src/zenserver/projectstore/remoteprojectstore.cpp
@@ -143,20 +143,8 @@ LogRemoteStoreStatsDetails(const RemoteProjectStore::Stats& Stats)
 }
 
 bool
-IterateBlock(const IoHash&																 BlockHash,
-			 IoBuffer&&																	 CompressedBlock,
-			 std::function<void(CompressedBuffer&& Chunk, const IoHash& AttachmentHash)> Visitor)
+IterateBlock(const SharedBuffer& BlockPayload, std::function<void(CompressedBuffer&& Chunk, const IoHash& AttachmentHash)> Visitor)
 {
-	IoHash	 RawHash;
-	uint64_t RawSize;
-	IoBuffer BlockPayload =
-		CompressedBuffer::FromCompressed(SharedBuffer(std::move(CompressedBlock)), RawHash, RawSize).Decompress().AsIoBuffer();
-	if (RawHash != BlockHash)
-	{
-		ZEN_WARN("Header rawhash for downloaded block {} does not match, got {}", BlockHash, RawHash);
-		return false;
-	}
-
 	MemoryView	   BlockView = BlockPayload.GetView();
 	const uint8_t* ReadPtr	 = reinterpret_cast<const uint8_t*>(BlockView.GetData());
 	uint32_t	   NumberSize;
@@ -2126,20 +2114,6 @@ ParseOplogContainer(const CbObject&																	  ContainerObject,
 
 	Stopwatch Timer;
 
-	size_t		NeedAttachmentCount = 0;
-	CbArrayView LargeChunksArray	= ContainerObject["chunks"sv].AsArrayView();
-	for (CbFieldView LargeChunksField : LargeChunksArray)
-	{
-		IoHash AttachmentHash = LargeChunksField.AsBinaryAttachment();
-		if (HasAttachment(AttachmentHash))
-		{
-			continue;
-		}
-		OnNeedAttachment(AttachmentHash);
-		NeedAttachmentCount++;
-	};
-	ReportMessage(OptionalContext, fmt::format("Requesting {} of {} large attachments", NeedAttachmentCount, LargeChunksArray.Num()));
-
 	size_t		NeedBlockCount = 0;
 	CbArrayView BlocksArray	   = ContainerObject["blocks"sv].AsArrayView();
 	for (CbFieldView BlockField : BlocksArray)
@@ -2185,6 +2159,21 @@ ParseOplogContainer(const CbObject&																	  ContainerObject,
 			}
 		}
 	}
+	ReportMessage(OptionalContext, fmt::format("Requesting {} of {} attachment blocks", NeedBlockCount, BlocksArray.Num()));
+
+	size_t		NeedAttachmentCount = 0;
+	CbArrayView LargeChunksArray	= ContainerObject["chunks"sv].AsArrayView();
+	for (CbFieldView LargeChunksField : LargeChunksArray)
+	{
+		IoHash AttachmentHash = LargeChunksField.AsBinaryAttachment();
+		if (HasAttachment(AttachmentHash))
+		{
+			continue;
+		}
+		OnNeedAttachment(AttachmentHash);
+		NeedAttachmentCount++;
+	};
+	ReportMessage(OptionalContext, fmt::format("Requesting {} of {} large attachments", NeedAttachmentCount, LargeChunksArray.Num()));
 
 	CbArrayView ChunkedFilesArray = ContainerObject["chunkedfiles"sv].AsArrayView();
 	for (CbFieldView ChunkedFileField : ChunkedFilesArray)
@@ -2215,8 +2204,6 @@ ParseOplogContainer(const CbObject&																	  ContainerObject,
 				 Chunked.ChunkHashes.size());
 	}
 
-	ReportMessage(OptionalContext, fmt::format("Requesting {} of {} attachment blocks", NeedBlockCount, BlocksArray.Num()));
-
 	MemoryView OpsSection = ContainerObject["ops"sv].AsBinaryView();
 	IoBuffer   OpsBuffer(IoBuffer::Wrap, OpsSection.GetData(), OpsSection.GetSize());
 	IoBuffer   SectionPayload = CompressedBuffer::FromCompressedNoValidate(std::move(OpsBuffer)).Decompress().AsIoBuffer();
@@ -2474,17 +2461,31 @@ LoadOplog(CidStore&			   ChunkStore,
 					{
 						return;
 					}
-					for (const auto& It : Chunks)
+
+					if (!Chunks.empty())
 					{
-						uint64_t ChunkSize = It.second.GetCompressedSize();
-						Info.AttachmentBytesDownloaded.fetch_add(ChunkSize);
-						CidStore::InsertResult InsertResult = ChunkStore.AddChunk(It.second.GetCompressed().Flatten().AsIoBuffer(),
-																				  It.first,
-																				  CidStore::InsertMode::kCopyOnly);
-						if (InsertResult.New)
+						std::vector<IoBuffer> WriteAttachmentBuffers;
+						std::vector<IoHash>	  WriteRawHashes;
+						WriteAttachmentBuffers.reserve(Chunks.size());
+						WriteRawHashes.reserve(Chunks.size());
+
+						for (const auto& It : Chunks)
 						{
-							Info.AttachmentBytesStored.fetch_add(ChunkSize);
-							Info.AttachmentsStored.fetch_add(1);
+							uint64_t ChunkSize = It.second.GetCompressedSize();
+							Info.AttachmentBytesDownloaded.fetch_add(ChunkSize);
+							WriteAttachmentBuffers.push_back(It.second.GetCompressed().Flatten().AsIoBuffer());
+							WriteRawHashes.push_back(It.first);
+						}
+						std::vector<CidStore::InsertResult> InsertResults =
+							ChunkStore.AddChunks(WriteAttachmentBuffers, WriteRawHashes, CidStore::InsertMode::kCopyOnly);
+
+						for (size_t Index = 0; Index < InsertResults.size(); Index++)
+						{
+							if (InsertResults[Index].New)
+							{
+								Info.AttachmentBytesStored.fetch_add(WriteAttachmentBuffers[Index].GetSize());
+								Info.AttachmentsStored.fetch_add(1);
+							}
 						}
 					}
 				});
@@ -2558,23 +2559,36 @@ LoadOplog(CidStore&			   ChunkStore,
 				std::unordered_set<IoHash, IoHash::Hasher> WantedChunks;
 				WantedChunks.reserve(Chunks.size());
 				WantedChunks.insert(Chunks.begin(), Chunks.end());
-				bool StoreChunksOK =
-					IterateBlock(BlockHash,
-								 IoBuffer(Bytes),
-								 [&ChunkStore, &WantedChunks, &Info](CompressedBuffer&& Chunk, const IoHash& AttachmentRawHash) {
-									 if (WantedChunks.contains(AttachmentRawHash))
-									 {
-										 uint64_t				ChunkSize = Chunk.GetCompressedSize();
-										 CidStore::InsertResult InsertResult =
-											 ChunkStore.AddChunk(Chunk.GetCompressed().Flatten().AsIoBuffer(), AttachmentRawHash);
-										 if (InsertResult.New)
-										 {
-											 Info.AttachmentBytesStored.fetch_add(ChunkSize);
-											 Info.AttachmentsStored.fetch_add(1);
-										 }
-										 WantedChunks.erase(AttachmentRawHash);
-									 }
-								 });
+				std::vector<IoBuffer> WriteAttachmentBuffers;
+				std::vector<IoHash>	  WriteRawHashes;
+
+				IoHash		 RawHash;
+				uint64_t	 RawSize;
+				SharedBuffer BlockPayload = CompressedBuffer::FromCompressed(SharedBuffer(Bytes), RawHash, RawSize).Decompress();
+				if (RawHash != BlockHash)
+				{
+					ReportMessage(OptionalContext, fmt::format("Block attachment {} has mismatching raw hash ({})", BlockHash, RawHash));
+					RemoteResult.SetError(gsl::narrow<int32_t>(HttpResponseCode::InternalServerError),
+										  fmt::format("Block attachment {} has mismatching raw hash ({})", BlockHash, RawHash),
+										  {});
+				}
+
+				bool StoreChunksOK = IterateBlock(
+					BlockPayload,
+					[&WantedChunks, &WriteAttachmentBuffers, &WriteRawHashes, &Info](CompressedBuffer&& Chunk,
+																					 const IoHash&		AttachmentRawHash) {
+						if (WantedChunks.contains(AttachmentRawHash))
+						{
+							WriteAttachmentBuffers.emplace_back(Chunk.GetCompressed().Flatten().AsIoBuffer());
+							IoHash	 RawHash;
+							uint64_t RawSize;
+							ZEN_ASSERT(CompressedBuffer::ValidateCompressedHeader(WriteAttachmentBuffers.back(), RawHash, RawSize));
+							ZEN_ASSERT(RawHash == AttachmentRawHash);
+							WriteRawHashes.emplace_back(AttachmentRawHash);
+							WantedChunks.erase(AttachmentRawHash);
+						}
+					});
+
 				if (!StoreChunksOK)
 				{
 					ReportMessage(OptionalContext,
@@ -2587,7 +2601,22 @@ LoadOplog(CidStore&			   ChunkStore,
 										  {});
 					return;
 				}
+
 				ZEN_ASSERT(WantedChunks.empty());
+
+				if (!WriteAttachmentBuffers.empty())
+				{
+					auto Results = ChunkStore.AddChunks(WriteAttachmentBuffers, WriteRawHashes);
+					for (size_t Index = 0; Index < Results.size(); Index++)
+					{
+						const auto& Result = Results[Index];
+						if (Result.New)
+						{
+							Info.AttachmentBytesStored.fetch_add(WriteAttachmentBuffers[Index].GetSize());
+							Info.AttachmentsStored.fetch_add(1);
+						}
+					}
+				}
 			});
 		});
 	};
diff --git a/src/zenserver/projectstore/remoteprojectstore.h b/src/zenserver/projectstore/remoteprojectstore.h
index d4ccd8c7b..d6e064bdf 100644
--- a/src/zenserver/projectstore/remoteprojectstore.h
+++ b/src/zenserver/projectstore/remoteprojectstore.h
@@ -162,8 +162,6 @@ RemoteProjectStore::Result LoadOplog(CidStore&			  ChunkStore,
 									 JobContext*		  OptionalContext);
 
 CompressedBuffer GenerateBlock(std::vector<std::pair<IoHash, FetchChunkFunc>>&& FetchChunks);
-bool			 IterateBlock(const IoHash&																  BlockHash,
-							  IoBuffer&&																  CompressedBlock,
-							  std::function<void(CompressedBuffer&& Chunk, const IoHash& AttachmentHash)> Visitor);
+bool IterateBlock(const SharedBuffer& BlockPayload, std::function<void(CompressedBuffer&& Chunk, const IoHash& AttachmentHash)> Visitor);
 
 }  // namespace zen
diff --git a/src/zenstore/blockstore.cpp b/src/zenstore/blockstore.cpp
index 644ddf7b4..8ef9e842f 100644
--- a/src/zenstore/blockstore.cpp
+++ b/src/zenstore/blockstore.cpp
@@ -453,6 +453,103 @@ BlockStore::WriteChunk(const void* Data, uint64_t Size, uint32_t Alignment, cons
 	}
 }
 
+void
+BlockStore::WriteChunks(std::span<IoBuffer> Datas, uint32_t Alignment, const WriteChunksCallback& Callback)
+{
+	ZEN_TRACE_CPU("BlockStore::WriteChunks");
+
+	ZEN_ASSERT(!Datas.empty());
+	ZEN_ASSERT(Alignment > 0u);
+
+	const size_t TotalCount	 = Datas.size();
+	uint64_t	 TotalSize	 = 0;
+	uint64_t	 LargestSize = 0;
+	for (const IoBuffer& Data : Datas)
+	{
+		uint64_t Size = Data.GetSize();
+		ZEN_ASSERT(Size > 0);
+		ZEN_ASSERT(Size <= m_MaxBlockSize);
+		TotalSize += Size;
+		LargestSize = Max(LargestSize, Size);
+	}
+
+	const uint64_t		 MinSize	= Max(LargestSize, 8u * 1024u * 1024u);
+	const uint64_t		 BufferSize = Min(TotalSize, MinSize);
+	std::vector<uint8_t> Buffer(BufferSize);
+
+	size_t Offset = 0;
+	while (Offset < TotalCount)
+	{
+		size_t	 Count	   = 1;
+		uint32_t RangeSize = gsl::narrow<uint32_t>(Datas[Offset].GetSize());
+
+		RwLock::ExclusiveLockScope InsertLock(m_InsertLock);
+		uint32_t				   WriteBlockIndex	   = m_WriteBlockIndex.load(std::memory_order_acquire);
+		uint32_t				   AlignedInsertOffset = RoundUp(m_CurrentInsertOffset, Alignment);
+		if ((!m_WriteBlock) || ((AlignedInsertOffset + RangeSize) > m_MaxBlockSize))
+		{
+			std::filesystem::path BlockPath;
+			WriteBlockIndex = GetFreeBlockIndex(WriteBlockIndex, InsertLock, BlockPath);
+			if (WriteBlockIndex == (uint32_t)m_MaxBlockCount)
+			{
+				throw std::runtime_error(fmt::format("unable to allocate a new block in '{}'", m_BlocksBasePath));
+			}
+			Ref<BlockStoreFile> NewBlockFile(new BlockStoreFile(BlockPath));
+			NewBlockFile->Create(m_MaxBlockSize);
+
+			m_ChunkBlocks[WriteBlockIndex] = NewBlockFile;
+			m_WriteBlock				   = NewBlockFile;
+			m_WriteBlockIndex.store(WriteBlockIndex, std::memory_order_release);
+			m_CurrentInsertOffset = 0;
+			AlignedInsertOffset	  = 0;
+		}
+		while (Offset + Count < TotalCount)
+		{
+			uint32_t NextRangeSize = gsl::narrow<uint32_t>(RoundUp(RangeSize, Alignment) + Datas[Offset + Count].GetSize());
+			if ((AlignedInsertOffset + NextRangeSize) > m_MaxBlockSize || (NextRangeSize > BufferSize))
+			{
+				break;
+			}
+			Count++;
+			RangeSize = NextRangeSize;
+		}
+		m_CurrentInsertOffset		   = AlignedInsertOffset + RangeSize;
+		Ref<BlockStoreFile> WriteBlock = m_WriteBlock;
+		m_ActiveWriteBlocks.push_back(WriteBlockIndex);
+		InsertLock.ReleaseNow();
+
+		{
+			MutableMemoryView WriteBuffer(Buffer.data(), RangeSize);
+			for (size_t Index = 0; Index < Count; Index++)
+			{
+				MemoryView SourceBuffer = Datas[Index + Offset];
+				WriteBuffer.CopyFrom(SourceBuffer);
+				WriteBuffer.MidInline(RoundUp(SourceBuffer.GetSize(), Alignment));
+			}
+			WriteBlock->Write(Buffer.data(), RangeSize, AlignedInsertOffset);
+		}
+
+		m_TotalSize.fetch_add(RangeSize, std::memory_order::relaxed);
+
+		uint32_t						ChunkOffset = AlignedInsertOffset;
+		std::vector<BlockStoreLocation> Locations(Count);
+		for (size_t Index = 0; Index < Count; Index++)
+		{
+			uint32_t ChunkSize = gsl::narrow<uint32_t>(Datas[Offset + Index].GetSize());
+			Locations[Index]   = {.BlockIndex = WriteBlockIndex, .Offset = ChunkOffset, .Size = ChunkSize};
+			ChunkOffset += gsl::narrow<uint32_t>(RoundUp(ChunkSize, Alignment));
+		}
+		Callback(Locations);
+
+		{
+			RwLock::ExclusiveLockScope _(m_InsertLock);
+			m_ActiveWriteBlocks.erase(std::find(m_ActiveWriteBlocks.begin(), m_ActiveWriteBlocks.end(), WriteBlockIndex));
+		}
+
+		Offset += Count;
+	}
+}
+
 BlockStore::ReclaimSnapshotState
 BlockStore::GetReclaimSnapshotState()
 {
@@ -1543,6 +1640,72 @@ namespace blockstore::impl {
 
 }  // namespace blockstore::impl
 
+TEST_CASE("blockstore.multichunks")
+{
+	using namespace blockstore::impl;
+
+	ScopedTemporaryDirectory TempDir;
+	auto					 RootDirectory = TempDir.Path();
+
+	BlockStore Store;
+	Store.Initialize(RootDirectory, 128, 1024);
+
+	std::vector<IoBuffer> MultiChunkData;
+	std::string			  FirstChunkData = "0123456789012345678901234567890123456789012345678901234567890123";
+	MultiChunkData.push_back(IoBuffer(IoBuffer::Wrap, FirstChunkData.data(), FirstChunkData.size()));
+
+	std::string SecondChunkData = "12345678901234567890123456789012345678901234567890123456";
+	MultiChunkData.push_back(IoBuffer(IoBuffer::Wrap, SecondChunkData.data(), SecondChunkData.size()));
+
+	std::string ThirdChunkData = "789012345678901234567890123456789012345678901234567890";
+	MultiChunkData.push_back(IoBuffer(IoBuffer::Wrap, ThirdChunkData.data(), ThirdChunkData.size()));
+
+	BlockStoreLocation Locations[5];
+	size_t			   ChunkOffset = 0;
+	Store.WriteChunks(MultiChunkData, 4, [&](std::span<BlockStoreLocation> InLocations) {
+		for (const BlockStoreLocation& Location : InLocations)
+		{
+			Locations[ChunkOffset++] = Location;
+		}
+		CHECK(ChunkOffset <= MultiChunkData.size());
+	});
+	CHECK(ChunkOffset == 3);
+
+	CHECK(ReadChunkAsString(Store, Locations[0]) == FirstChunkData);
+	CHECK(Locations[1].BlockIndex == Locations[0].BlockIndex);
+	CHECK(ReadChunkAsString(Store, Locations[1]) == SecondChunkData);
+	CHECK(Locations[2].BlockIndex != Locations[1].BlockIndex);
+	CHECK(ReadChunkAsString(Store, Locations[2]) == ThirdChunkData);
+
+	MultiChunkData.resize(0);
+	std::string FourthChunkData = "ABCDEFGHIJABCDEFGHIJ_23";
+	MultiChunkData.push_back(IoBuffer(IoBuffer::Wrap, FourthChunkData.data(), FourthChunkData.size()));
+
+	std::string FifthChunkData =
+		"ABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJABCDEFGHIJ_93";
+	MultiChunkData.push_back(IoBuffer(IoBuffer::Wrap, FifthChunkData.data(), FifthChunkData.size()));
+
+	Store.WriteChunks(MultiChunkData, 4, [&](std::span<BlockStoreLocation> InLocations) {
+		for (const BlockStoreLocation& Location : InLocations)
+		{
+			CHECK(ChunkOffset < 5);
+			Locations[ChunkOffset++] = Location;
+		}
+	});
+	CHECK(ChunkOffset == 5);
+
+	CHECK(ReadChunkAsString(Store, Locations[0]) == FirstChunkData);
+	CHECK(Locations[1].BlockIndex == Locations[0].BlockIndex);
+	CHECK(ReadChunkAsString(Store, Locations[1]) == SecondChunkData);
+	CHECK(Locations[2].BlockIndex != Locations[1].BlockIndex);
+	CHECK(ReadChunkAsString(Store, Locations[2]) == ThirdChunkData);
+
+	CHECK(Locations[3].BlockIndex == Locations[2].BlockIndex);
+	CHECK(ReadChunkAsString(Store, Locations[3]) == FourthChunkData);
+	CHECK(Locations[4].BlockIndex != Locations[3].BlockIndex);
+	CHECK(ReadChunkAsString(Store, Locations[4]) == FifthChunkData);
+}
+
 TEST_CASE("blockstore.chunks")
 {
 	using namespace blockstore::impl;
diff --git a/src/zenstore/cache/cacherpc.cpp b/src/zenstore/cache/cacherpc.cpp
index 3cb1b03a5..60b2fa1a1 100644
--- a/src/zenstore/cache/cacherpc.cpp
+++ b/src/zenstore/cache/cacherpc.cpp
@@ -315,49 +315,58 @@ CacheRpcHandler::PutCacheRecord(PutRequestData& Request, const CbPackage* Packag
 	uint64_t	 RecordObjectSize = Record.GetSize();
 	uint64_t	 TransferredSize  = RecordObjectSize;
 
-	AttachmentCount					 Count;
-	size_t							 NumAttachments = Package->GetAttachments().size();
-	std::vector<IoHash>				 ValidAttachments;
-	std::vector<IoHash>				 ReferencedAttachments;
-	std::vector<const CbAttachment*> AttachmentsToStoreLocally;
+	AttachmentCount		  Count;
+	size_t				  NumAttachments = Package->GetAttachments().size();
+	std::vector<IoHash>	  ValidAttachments;
+	std::vector<IoHash>	  ReferencedAttachments;
+	std::vector<IoBuffer> WriteAttachmentBuffers;
+	std::vector<IoHash>	  WriteRawHashes;
 	ValidAttachments.reserve(NumAttachments);
-	AttachmentsToStoreLocally.reserve(NumAttachments);
+	WriteAttachmentBuffers.reserve(NumAttachments);
+	WriteRawHashes.reserve(NumAttachments);
 
 	const bool HasUpstream = m_UpstreamCache.IsActive();
 
 	Stopwatch Timer;
 
-	Request.RecordObject.IterateAttachments(
-		[this, &Request, Package, &AttachmentsToStoreLocally, &ValidAttachments, &ReferencedAttachments, &Count, &TransferredSize](
-			CbFieldView HashView) {
-			const IoHash ValueHash = HashView.AsHash();
-			ReferencedAttachments.push_back(ValueHash);
-			if (const CbAttachment* Attachment = Package ? Package->FindAttachment(ValueHash) : nullptr)
-			{
-				if (Attachment->IsCompressedBinary())
-				{
-					AttachmentsToStoreLocally.emplace_back(Attachment);
-					ValidAttachments.emplace_back(ValueHash);
-					Count.Valid++;
-				}
-				else
-				{
-					ZEN_WARN("PUTCACHERECORD - '{}/{}/{}' '{}' FAILED, attachment '{}' is not compressed",
-							 Request.Namespace,
-							 Request.Key.Bucket,
-							 Request.Key.Hash,
-							 ToString(ZenContentType::kCbPackage),
-							 ValueHash);
-					Count.Invalid++;
-				}
-			}
-			else if (m_CidStore.ContainsChunk(ValueHash))
+	Request.RecordObject.IterateAttachments([this,
+											 &Request,
+											 Package,
+											 &WriteAttachmentBuffers,
+											 &WriteRawHashes,
+											 &ValidAttachments,
+											 &ReferencedAttachments,
+											 &Count,
+											 &TransferredSize](CbFieldView HashView) {
+		const IoHash ValueHash = HashView.AsHash();
+		ReferencedAttachments.push_back(ValueHash);
+		if (const CbAttachment* Attachment = Package ? Package->FindAttachment(ValueHash) : nullptr)
+		{
+			if (Attachment->IsCompressedBinary())
 			{
+				WriteAttachmentBuffers.push_back(Attachment->AsCompressedBinary().GetCompressed().Flatten().AsIoBuffer());
+				WriteRawHashes.push_back(ValueHash);
 				ValidAttachments.emplace_back(ValueHash);
 				Count.Valid++;
 			}
-			Count.Total++;
-		});
+			else
+			{
+				ZEN_WARN("PUTCACHERECORD - '{}/{}/{}' '{}' FAILED, attachment '{}' is not compressed",
+						 Request.Namespace,
+						 Request.Key.Bucket,
+						 Request.Key.Hash,
+						 ToString(ZenContentType::kCbPackage),
+						 ValueHash);
+				Count.Invalid++;
+			}
+		}
+		else if (m_CidStore.ContainsChunk(ValueHash))
+		{
+			ValidAttachments.emplace_back(ValueHash);
+			Count.Valid++;
+		}
+		Count.Total++;
+	});
 
 	if (Count.Invalid > 0)
 	{
@@ -371,16 +380,20 @@ CacheRpcHandler::PutCacheRecord(PutRequestData& Request, const CbPackage* Packag
 	m_CacheStore.Put(Request.Context, Request.Namespace, Request.Key.Bucket, Request.Key.Hash, CacheValue, ReferencedAttachments);
 	m_CacheStats.WriteCount++;
 
-	for (const CbAttachment* Attachment : AttachmentsToStoreLocally)
+	if (!WriteAttachmentBuffers.empty())
 	{
-		CompressedBuffer	   Chunk		= Attachment->AsCompressedBinary();
-		CidStore::InsertResult InsertResult = m_CidStore.AddChunk(Chunk.GetCompressed().Flatten().AsIoBuffer(), Attachment->GetHash());
-		if (InsertResult.New)
+		std::vector<CidStore::InsertResult> InsertResults = m_CidStore.AddChunks(WriteAttachmentBuffers, WriteRawHashes);
+		for (size_t Index = 0; Index < InsertResults.size(); Index++)
 		{
-			Count.New++;
+			if (InsertResults[Index].New)
+			{
+				Count.New++;
+			}
+			TransferredSize += WriteAttachmentBuffers[Index].GetSize();
 		}
-		TransferredSize += Chunk.GetCompressedSize();
 	}
+	WriteAttachmentBuffers = {};
+	WriteRawHashes		   = {};
 
 	ZEN_DEBUG("PUTCACHERECORD - '{}/{}/{}' {}, attachments '{}/{}/{}' (new/valid/total) in {}",
 			  Request.Namespace,
diff --git a/src/zenstore/cas.cpp b/src/zenstore/cas.cpp
index a1a4a0acc..2fe466028 100644
--- a/src/zenstore/cas.cpp
+++ b/src/zenstore/cas.cpp
@@ -49,15 +49,18 @@ public:
 	CasImpl(GcManager& Gc);
 	virtual ~CasImpl();
 
-	virtual void				   Initialize(const CidStoreConfiguration& InConfig) override;
-	virtual CasStore::InsertResult InsertChunk(IoBuffer Chunk, const IoHash& ChunkHash, InsertMode Mode) override;
-	virtual IoBuffer			   FindChunk(const IoHash& ChunkHash) override;
-	virtual bool				   ContainsChunk(const IoHash& ChunkHash) override;
-	virtual void				   FilterChunks(HashKeySet& InOutChunks) override;
-	virtual void				   Flush() override;
-	virtual void				   ScrubStorage(ScrubContext& Ctx) override;
-	virtual void				   GarbageCollect(GcContext& GcCtx) override;
-	virtual CidStoreSize		   TotalSize() const override;
+	virtual void					  Initialize(const CidStoreConfiguration& InConfig) override;
+	virtual CasStore::InsertResult	  InsertChunk(IoBuffer Chunk, const IoHash& ChunkHash, InsertMode Mode) override;
+	virtual std::vector<InsertResult> InsertChunks(std::span<IoBuffer> Data,
+												   std::span<IoHash>   ChunkHashes,
+												   InsertMode		   Mode = InsertMode::kMayBeMovedInPlace) override;
+	virtual IoBuffer				  FindChunk(const IoHash& ChunkHash) override;
+	virtual bool					  ContainsChunk(const IoHash& ChunkHash) override;
+	virtual void					  FilterChunks(HashKeySet& InOutChunks) override;
+	virtual void					  Flush() override;
+	virtual void					  ScrubStorage(ScrubContext& Ctx) override;
+	virtual void					  GarbageCollect(GcContext& GcCtx) override;
+	virtual CidStoreSize			  TotalSize() const override;
 
 private:
 	CasContainerStrategy m_TinyStrategy;
@@ -250,6 +253,108 @@ CasImpl::InsertChunk(IoBuffer Chunk, const IoHash& ChunkHash, InsertMode Mode)
 	return m_LargeStrategy.InsertChunk(Chunk, ChunkHash, Mode);
 }
 
+static void
+GetCompactCasResults(CasContainerStrategy&				 Strategy,
+					 std::span<IoBuffer>				 Data,
+					 std::span<IoHash>					 ChunkHashes,
+					 std::span<size_t>					 Indexes,
+					 std::vector<CasStore::InsertResult> Results)
+{
+	const size_t Count = Indexes.size();
+	if (Count == 1)
+	{
+		const size_t Index = Indexes[0];
+		Results[Index]	   = Strategy.InsertChunk(Data[Index], ChunkHashes[Index]);
+		return;
+	}
+	std::vector<IoBuffer> Chunks;
+	std::vector<IoHash>	  Hashes;
+	Chunks.reserve(Count);
+	Hashes.reserve(Count);
+	for (size_t Index : Indexes)
+	{
+		Chunks.push_back(Data[Index]);
+		Hashes.push_back(ChunkHashes[Index]);
+	}
+
+	Strategy.InsertChunks(Chunks, Hashes);
+
+	for (size_t Offset = 0; Offset < Count; Offset++)
+	{
+		size_t Index   = Indexes[Offset];
+		Results[Index] = Results[Offset];
+	}
+};
+
+static void
+GetFileCasResults(FileCasStrategy&					  Strategy,
+				  CasStore::InsertMode				  Mode,
+				  std::span<IoBuffer>				  Data,
+				  std::span<IoHash>					  ChunkHashes,
+				  std::span<size_t>					  Indexes,
+				  std::vector<CasStore::InsertResult> Results)
+{
+	for (size_t Index : Indexes)
+	{
+		Results[Index] = Strategy.InsertChunk(Data[Index], ChunkHashes[Index], Mode);
+	}
+};
+
+std::vector<CasStore::InsertResult>
+CasImpl::InsertChunks(std::span<IoBuffer> Data, std::span<IoHash> ChunkHashes, CasStore::InsertMode Mode)
+{
+	ZEN_TRACE_CPU("CAS::InsertChunks");
+	ZEN_ASSERT(Data.size() == ChunkHashes.size());
+
+	if (Data.size() == 1)
+	{
+		std::vector<CasStore::InsertResult> Result(1);
+		Result[0] = InsertChunk(Data[0], ChunkHashes[0], Mode);
+		return Result;
+	}
+
+	std::vector<size_t> TinyIndexes;
+	std::vector<size_t> SmallIndexes;
+	std::vector<size_t> LargeIndexes;
+
+	for (size_t Index = 0; Index < Data.size(); Index++)
+	{
+		const uint64_t ChunkSize = Data[Index].Size();
+		if (ChunkSize < m_Config.TinyValueThreshold)
+		{
+			ZEN_ASSERT(ChunkSize);
+			TinyIndexes.push_back(Index);
+		}
+		else if (ChunkSize < m_Config.HugeValueThreshold)
+		{
+			SmallIndexes.push_back(Index);
+		}
+		else
+		{
+			LargeIndexes.push_back(Index);
+		}
+	}
+
+	std::vector<CasStore::InsertResult> Result(Data.size());
+
+	if (!TinyIndexes.empty())
+	{
+		GetCompactCasResults(m_TinyStrategy, Data, ChunkHashes, TinyIndexes, Result);
+	}
+
+	if (!SmallIndexes.empty())
+	{
+		GetCompactCasResults(m_SmallStrategy, Data, ChunkHashes, SmallIndexes, Result);
+	}
+
+	if (!LargeIndexes.empty())
+	{
+		GetFileCasResults(m_LargeStrategy, Mode, Data, ChunkHashes, LargeIndexes, Result);
+	}
+
+	return Result;
+}
+
 IoBuffer
 CasImpl::FindChunk(const IoHash& ChunkHash)
 {
diff --git a/src/zenstore/cas.h b/src/zenstore/cas.h
index b951d6d59..f93724905 100644
--- a/src/zenstore/cas.h
+++ b/src/zenstore/cas.h
@@ -40,13 +40,16 @@ public:
 
 	virtual void		 Initialize(const CidStoreConfiguration& Config)													   = 0;
 	virtual InsertResult InsertChunk(IoBuffer Data, const IoHash& ChunkHash, InsertMode Mode = InsertMode::kMayBeMovedInPlace) = 0;
-	virtual IoBuffer	 FindChunk(const IoHash& ChunkHash)																	   = 0;
-	virtual bool		 ContainsChunk(const IoHash& ChunkHash)																   = 0;
-	virtual void		 FilterChunks(HashKeySet& InOutChunks)																   = 0;
-	virtual void		 Flush()																							   = 0;
-	virtual void		 ScrubStorage(ScrubContext& Ctx)																	   = 0;
-	virtual void		 GarbageCollect(GcContext& GcCtx)																	   = 0;
-	virtual CidStoreSize TotalSize() const																					   = 0;
+	virtual std::vector<InsertResult> InsertChunks(std::span<IoBuffer> Data,
+												   std::span<IoHash>   ChunkHashes,
+												   InsertMode		   Mode = InsertMode::kMayBeMovedInPlace)						   = 0;
+	virtual IoBuffer				  FindChunk(const IoHash& ChunkHash)													   = 0;
+	virtual bool					  ContainsChunk(const IoHash& ChunkHash)												   = 0;
+	virtual void					  FilterChunks(HashKeySet& InOutChunks)													   = 0;
+	virtual void					  Flush()																				   = 0;
+	virtual void					  ScrubStorage(ScrubContext& Ctx)														   = 0;
+	virtual void					  GarbageCollect(GcContext& GcCtx)														   = 0;
+	virtual CidStoreSize			  TotalSize() const																		   = 0;
 
 protected:
 	CidStoreConfiguration m_Config;
diff --git a/src/zenstore/cidstore.cpp b/src/zenstore/cidstore.cpp
index 67b7e95ac..68bccd06b 100644
--- a/src/zenstore/cidstore.cpp
+++ b/src/zenstore/cidstore.cpp
@@ -45,6 +45,50 @@ struct CidStore::Impl
 		return {.New = Result.New};
 	}
 
+	std::vector<CidStore::InsertResult> AddChunks(std::span<IoBuffer> ChunkDatas, std::span<IoHash> RawHashes, CidStore::InsertMode Mode)
+	{
+		if (ChunkDatas.size() == 1)
+		{
+			std::vector<CidStore::InsertResult> Result(1);
+			Result[0] = AddChunk(ChunkDatas[0], RawHashes[0], Mode);
+			return Result;
+		}
+		ZEN_ASSERT(ChunkDatas.size() == RawHashes.size());
+		std::vector<IoBuffer> Chunks;
+		Chunks.reserve(ChunkDatas.size());
+#if ZEN_BUILD_DEBUG
+		size_t Offset = 0;
+#endif
+		uint64_t TotalSize = 0;
+		for (const IoBuffer& ChunkData : ChunkDatas)
+		{
+			TotalSize += ChunkData.GetSize();
+#if ZEN_BUILD_DEBUG
+			IoHash	 VerifyRawHash;
+			uint64_t _;
+			ZEN_ASSERT(CompressedBuffer::ValidateCompressedHeader(ChunkData, VerifyRawHash, _) && RawHashes[Offset++] == VerifyRawHash);
+#endif
+			Chunks.push_back(ChunkData);
+			Chunks.back().SetContentType(ZenContentType::kCompressedBinary);
+		}
+
+		metrics::RequestStats::Scope $(m_AddChunkOps, TotalSize);
+
+		std::vector<CasStore::InsertResult> CasResults =
+			m_CasStore.InsertChunks(Chunks, RawHashes, static_cast<CasStore::InsertMode>(Mode));
+		ZEN_ASSERT(CasResults.size() == ChunkDatas.size());
+		std::vector<CidStore::InsertResult> Result;
+		for (const CasStore::InsertResult& CasResult : CasResults)
+		{
+			if (CasResult.New)
+			{
+				m_WriteCount++;
+			}
+			Result.emplace_back(CidStore::InsertResult{.New = CasResult.New});
+		}
+		return Result;
+	}
+
 	IoBuffer FindChunkByCid(const IoHash& DecompressedId)
 	{
 		metrics::RequestStats::Scope StatsScope(m_FindChunkOps, 0);
@@ -145,6 +189,12 @@ CidStore::AddChunk(const IoBuffer& ChunkData, const IoHash& RawHash, InsertMode
 	return m_Impl->AddChunk(ChunkData, RawHash, Mode);
 }
 
+std::vector<CidStore::InsertResult>
+CidStore::AddChunks(std::span<IoBuffer> ChunkDatas, std::span<IoHash> RawHashes, InsertMode Mode)
+{
+	return m_Impl->AddChunks(ChunkDatas, RawHashes, Mode);
+}
+
 IoBuffer
 CidStore::FindChunkByCid(const IoHash& DecompressedId)
 {
diff --git a/src/zenstore/compactcas.cpp b/src/zenstore/compactcas.cpp
index 84905df15..ec2bfbdec 100644
--- a/src/zenstore/compactcas.cpp
+++ b/src/zenstore/compactcas.cpp
@@ -204,6 +204,64 @@ CasContainerStrategy::InsertChunk(IoBuffer Chunk, const IoHash& ChunkHash)
 	return InsertChunk(Chunk.Data(), Chunk.Size(), ChunkHash);
 }
 
+std::vector<CasStore::InsertResult>
+CasContainerStrategy::InsertChunks(std::span<IoBuffer> Chunks, std::span<IoHash> ChunkHashes)
+{
+	ZEN_ASSERT(Chunks.size() == ChunkHashes.size());
+	std::vector<CasStore::InsertResult> Result(Chunks.size());
+	std::vector<size_t>					NewChunkIndexes;
+	Result.reserve(Chunks.size());
+	{
+		RwLock::SharedLockScope _(m_LocationMapLock);
+		for (size_t ChunkIndex = 0; ChunkIndex < ChunkHashes.size(); ChunkIndex++)
+		{
+			const IoHash& ChunkHash = ChunkHashes[ChunkIndex];
+			bool		  IsNew		= !m_LocationMap.contains(ChunkHash);
+			Result[ChunkIndex]		= CasStore::InsertResult{.New = IsNew};
+			if (IsNew)
+			{
+				NewChunkIndexes.push_back(ChunkIndex);
+			}
+		}
+	}
+
+	if (NewChunkIndexes.empty())
+	{
+		return Result;
+	}
+
+	std::vector<IoBuffer> Datas;
+	for (size_t ChunkIndex : NewChunkIndexes)
+	{
+		const IoBuffer& Chunk = Chunks[ChunkIndex];
+#if !ZEN_WITH_TESTS
+		ZEN_ASSERT(Chunk.GetContentType() == ZenContentType::kCompressedBinary);
+#endif
+		Datas.emplace_back(Chunk);
+	}
+
+	size_t ChunkOffset = 0;
+	m_BlockStore.WriteChunks(Datas, m_PayloadAlignment, [&](std::span<BlockStoreLocation> Locations) {
+		std::vector<CasDiskIndexEntry> IndexEntries;
+		for (const BlockStoreLocation& Location : Locations)
+		{
+			size_t ChunkIndex = NewChunkIndexes[ChunkOffset++];
+			IndexEntries.emplace_back(
+				CasDiskIndexEntry{.Key = ChunkHashes[ChunkIndex], .Location = BlockStoreDiskLocation(Location, m_PayloadAlignment)});
+		}
+		m_CasLog.Append(IndexEntries);
+		{
+			RwLock::ExclusiveLockScope _(m_LocationMapLock);
+			for (const CasDiskIndexEntry& DiskIndexEntry : IndexEntries)
+			{
+				m_LocationMap.emplace(DiskIndexEntry.Key, m_Locations.size());
+				m_Locations.push_back(DiskIndexEntry.Location);
+			}
+		}
+	});
+	return Result;
+}
+
 IoBuffer
 CasContainerStrategy::FindChunk(const IoHash& ChunkHash)
 {
diff --git a/src/zenstore/compactcas.h b/src/zenstore/compactcas.h
index 932844da7..eb1d36b31 100644
--- a/src/zenstore/compactcas.h
+++ b/src/zenstore/compactcas.h
@@ -51,16 +51,17 @@ struct CasContainerStrategy final : public GcStorage, public GcReferenceStore
 	CasContainerStrategy(GcManager& Gc);
 	~CasContainerStrategy();
 
-	CasStore::InsertResult InsertChunk(IoBuffer Chunk, const IoHash& ChunkHash);
-	IoBuffer			   FindChunk(const IoHash& ChunkHash);
-	bool				   HaveChunk(const IoHash& ChunkHash);
-	void				   FilterChunks(HashKeySet& InOutChunks);
-	void				   Initialize(const std::filesystem::path& RootDirectory,
-									  const std::string_view	   ContainerBaseName,
-									  uint32_t					   MaxBlockSize,
-									  uint32_t					   Alignment,
-									  bool						   IsNewStore);
-	void				   Flush();
+	CasStore::InsertResult				InsertChunk(IoBuffer Chunk, const IoHash& ChunkHash);
+	std::vector<CasStore::InsertResult> InsertChunks(std::span<IoBuffer> Chunks, std::span<IoHash> ChunkHashes);
+	IoBuffer							FindChunk(const IoHash& ChunkHash);
+	bool								HaveChunk(const IoHash& ChunkHash);
+	void								FilterChunks(HashKeySet& InOutChunks);
+	void								Initialize(const std::filesystem::path& RootDirectory,
+												   const std::string_view		ContainerBaseName,
+												   uint32_t						MaxBlockSize,
+												   uint32_t						Alignment,
+												   bool							IsNewStore);
+	void								Flush();
 
 	// GcStorage
 
diff --git a/src/zenstore/include/zenstore/blockstore.h b/src/zenstore/include/zenstore/blockstore.h
index 656040936..c28aa8102 100644
--- a/src/zenstore/include/zenstore/blockstore.h
+++ b/src/zenstore/include/zenstore/blockstore.h
@@ -161,6 +161,9 @@ public:
 
 	void WriteChunk(const void* Data, uint64_t Size, uint32_t Alignment, const WriteChunkCallback& Callback);
 
+	typedef std::function<void(std::span<BlockStoreLocation> Locations)> WriteChunksCallback;
+	void WriteChunks(std::span<IoBuffer> Datas, uint32_t Alignment, const WriteChunksCallback& Callback);
+
 	IoBuffer TryGetChunk(const BlockStoreLocation& Location) const;
 	void	 Flush(bool ForceNewBlock);
 
diff --git a/src/zenstore/include/zenstore/cidstore.h b/src/zenstore/include/zenstore/cidstore.h
index 4c9f30608..54f562767 100644
--- a/src/zenstore/include/zenstore/cidstore.h
+++ b/src/zenstore/include/zenstore/cidstore.h
@@ -73,15 +73,18 @@ public:
 		kMayBeMovedInPlace
 	};
 
-	void			 Initialize(const CidStoreConfiguration& Config);
-	InsertResult	 AddChunk(const IoBuffer& ChunkData, const IoHash& RawHash, InsertMode Mode = InsertMode::kMayBeMovedInPlace);
-	virtual IoBuffer FindChunkByCid(const IoHash& DecompressedId) override;
-	bool			 ContainsChunk(const IoHash& DecompressedId);
-	void			 FilterChunks(HashKeySet& InOutChunks);
-	void			 Flush();
-	void			 ScrubStorage(ScrubContext& Ctx);
-	CidStoreSize	 TotalSize() const;
-	CidStoreStats	 Stats() const;
+	void					  Initialize(const CidStoreConfiguration& Config);
+	InsertResult			  AddChunk(const IoBuffer& ChunkData, const IoHash& RawHash, InsertMode Mode = InsertMode::kMayBeMovedInPlace);
+	std::vector<InsertResult> AddChunks(std::span<IoBuffer> ChunkDatas,
+										std::span<IoHash>	RawHashes,
+										InsertMode			Mode = InsertMode::kMayBeMovedInPlace);
+	virtual IoBuffer		  FindChunkByCid(const IoHash& DecompressedId) override;
+	bool					  ContainsChunk(const IoHash& DecompressedId);
+	void					  FilterChunks(HashKeySet& InOutChunks);
+	void					  Flush();
+	void					  ScrubStorage(ScrubContext& Ctx);
+	CidStoreSize			  TotalSize() const;
+	CidStoreStats			  Stats() const;
 
 	virtual void ReportMetrics(StatsMetrics& Statsd) override;