diff --git a/src/api/s3/put.rs b/src/api/s3/put.rs
index dc0530df..97b8e4e3 100644
--- a/src/api/s3/put.rs
+++ b/src/api/s3/put.rs
@@ -1,4 +1,4 @@
-use std::collections::{BTreeMap, BTreeSet, HashMap, VecDeque};
+use std::collections::{BTreeMap, BTreeSet, HashMap};
 use std::sync::Arc;
 
 use futures::prelude::*;
@@ -13,6 +13,7 @@ use opentelemetry::{
 	Context,
 };
 
+use garage_rpc::netapp::bytes_buf::BytesBuf;
 use garage_table::*;
 use garage_util::async_hash::*;
 use garage_util::data::*;
@@ -108,7 +109,7 @@ pub(crate) async fn save_stream<S: Stream<Item = Result<Bytes, Error>> + Unpin>(
 					size,
 					etag: data_md5sum_hex.clone(),
 				},
-				first_block,
+				first_block.to_vec(),
 			)),
 		};
 
@@ -136,7 +137,6 @@ pub(crate) async fn save_stream<S: Stream<Item = Result<Bytes, Error>> + Unpin>(
 	garage.version_table.insert(&version).await?;
 
 	// Transfer data and verify checksum
-	let first_block = Bytes::from(first_block);
 	let first_block_hash = async_blake2sum(first_block.clone()).await;
 
 	let tx_result = (|| async {
@@ -318,7 +318,6 @@ async fn read_and_put_blocks<S: Stream<Item = Result<Bytes, Error>> + Unpin>(
 			chunker.next(),
 		)?;
 		if let Some(block) = next_block {
-			let block = Bytes::from(block);
 			let (_, _, block_hash) = futures::future::join3(
 				md5hasher.update(block.clone()),
 				sha256hasher.update(block.clone()),
@@ -387,8 +386,7 @@ struct StreamChunker<S: Stream<Item = Result<Bytes, Error>>> {
 	stream: S,
 	read_all: bool,
 	block_size: usize,
-	buf: VecDeque<Bytes>,
-	buf_len: usize,
+	buf: BytesBuf,
 }
 
 impl<S: Stream<Item = Result<Bytes, Error>> + Unpin> StreamChunker<S> {
@@ -397,45 +395,25 @@ impl<S: Stream<Item = Result<Bytes, Error>> + Unpin> StreamChunker<S> {
 			stream,
 			read_all: false,
 			block_size,
-			buf: VecDeque::with_capacity(8),
-			buf_len: 0,
+			buf: BytesBuf::new(),
 		}
 	}
 
-	async fn next(&mut self) -> Result<Option<Vec<u8>>, Error> {
-		while !self.read_all && self.buf_len < self.block_size {
+	async fn next(&mut self) -> Result<Option<Bytes>, Error> {
+		while !self.read_all && self.buf.len() < self.block_size {
 			if let Some(block) = self.stream.next().await {
 				let bytes = block?;
 				trace!("Body next: {} bytes", bytes.len());
-				self.buf_len += bytes.len();
-				self.buf.push_back(bytes);
+				self.buf.extend(bytes);
 			} else {
 				self.read_all = true;
 			}
 		}
 
-		if self.buf_len == 0 {
+		if self.buf.is_empty() {
 			Ok(None)
 		} else {
-			let mut slices = Vec::with_capacity(self.buf.len());
-			let mut taken = 0;
-			while self.buf_len > 0 && taken < self.block_size {
-				let front = self.buf.pop_front().unwrap();
-				if taken + front.len() <= self.block_size {
-					taken += front.len();
-					self.buf_len -= front.len();
-					slices.push(front);
-				} else {
-					let front_take = self.block_size - taken;
-					slices.push(front.slice(..front_take));
-					self.buf.push_front(front.slice(front_take..));
-					self.buf_len -= front_take;
-					break;
-				}
-			}
-			Ok(Some(
-				slices.iter().map(|x| &x[..]).collect::<Vec<_>>().concat(),
-			))
+			Ok(Some(self.buf.take_max(self.block_size)))
 		}
 	}
 }
@@ -545,7 +523,6 @@ pub async fn handle_put_part(
 	// Copy block to store
 	let version = Version::new(version_uuid, bucket_id, key, false);
 
-	let first_block = Bytes::from(first_block);
 	let first_block_hash = async_blake2sum(first_block.clone()).await;
 
 	let (_, data_md5sum, data_sha256sum) = read_and_put_blocks(