diff --git a/pageserver/src/tenant/storage_layer/delta_layer.rs b/pageserver/src/tenant/storage_layer/delta_layer.rs
index b1976f6fa3..b0477fc308 100644
--- a/pageserver/src/tenant/storage_layer/delta_layer.rs
+++ b/pageserver/src/tenant/storage_layer/delta_layer.rs
@@ -44,8 +44,8 @@ use crate::tenant::vectored_blob_io::{
 use crate::tenant::PageReconstructError;
 use crate::virtual_file::owned_buffers_io::io_buf_ext::{FullSlice, IoBufExt};
 use crate::virtual_file::owned_buffers_io::write::Buffer;
-use crate::virtual_file::IoBufferMut;
 use crate::virtual_file::{self, MaybeFatalIo, VirtualFile};
+use crate::virtual_file::{IoBuffer, IoBufferMut};
 use crate::TEMP_FILE_SUFFIX;
 use crate::{DELTA_FILE_MAGIC, STORAGE_FORMAT_VERSION};
 use anyhow::{anyhow, bail, ensure, Context, Result};
@@ -70,6 +70,7 @@ use std::sync::Arc;
 use tokio::sync::OnceCell;
 use tokio_epoll_uring::IoBuf;
 use tracing::*;
+use utils::bin_ser::SerializeError;
 
 use utils::{
     bin_ser::BeSer,
@@ -114,6 +115,15 @@ impl From<&DeltaLayer> for Summary {
 }
 
 impl Summary {
+    /// Serializes the summary header into an aligned buffer of lenth `PAGE_SZ`.
+    pub fn ser_into_page(&self) -> Result<IoBuffer, SerializeError> {
+        let mut buf = IoBufferMut::with_capacity(PAGE_SZ);
+        Self::ser_into(&self, &mut buf)?;
+        // Pad zeroes to the buffer so the length is a multiple of the alignment.
+        buf.extend_with(0, buf.capacity() - buf.len());
+        Ok(buf.freeze())
+    }
+
     pub(super) fn expected(
         tenant_id: TenantId,
         timeline_id: TimelineId,
@@ -556,11 +566,9 @@ impl DeltaLayerWriterInner {
             index_root_blk,
         };
 
-        let mut buf = IoBufferMut::with_capacity(PAGE_SZ);
-        // TODO: could use smallvec here but it's a pain with Slice<T>
-        Summary::ser_into(&summary, &mut buf)?;
-        buf.extend_with(0, buf.capacity() - buf.len());
-        let (_buf, res) = file.write_all_at(buf.freeze().slice_len(), 0, ctx).await;
+        // Writes summary at the first block (offset 0).
+        let buf = summary.ser_into_page()?;
+        let (_buf, res) = file.write_all_at(buf.slice_len(), 0, ctx).await;
         res?;
 
         let metadata = file
@@ -773,11 +781,8 @@ impl DeltaLayer {
 
         let new_summary = rewrite(actual_summary);
 
-        let mut buf = IoBufferMut::with_capacity(PAGE_SZ);
-        // TODO: could use smallvec here, but it's a pain with Slice<T>
-        Summary::ser_into(&new_summary, &mut buf).context("serialize")?;
-        buf.extend_with(0, buf.capacity() - buf.len());
-        let (_buf, res) = file.write_all_at(buf.freeze().slice_len(), 0, ctx).await;
+        let buf = new_summary.ser_into_page().context("serialize")?;
+        let (_buf, res) = file.write_all_at(buf.slice_len(), 0, ctx).await;
         res?;
         Ok(())
     }
diff --git a/pageserver/src/tenant/storage_layer/image_layer.rs b/pageserver/src/tenant/storage_layer/image_layer.rs
index da25624568..932cf20745 100644
--- a/pageserver/src/tenant/storage_layer/image_layer.rs
+++ b/pageserver/src/tenant/storage_layer/image_layer.rs
@@ -41,8 +41,8 @@ use crate::tenant::vectored_blob_io::{
 use crate::tenant::PageReconstructError;
 use crate::virtual_file::owned_buffers_io::io_buf_ext::IoBufExt;
 use crate::virtual_file::owned_buffers_io::write::Buffer;
-use crate::virtual_file::IoBufferMut;
 use crate::virtual_file::{self, MaybeFatalIo, VirtualFile};
+use crate::virtual_file::{IoBuffer, IoBufferMut};
 use crate::{IMAGE_FILE_MAGIC, STORAGE_FORMAT_VERSION, TEMP_FILE_SUFFIX};
 use anyhow::{anyhow, bail, ensure, Context, Result};
 use bytes::Bytes;
@@ -66,6 +66,7 @@ use std::sync::Arc;
 use tokio::sync::OnceCell;
 use tokio_stream::StreamExt;
 use tracing::*;
+use utils::bin_ser::SerializeError;
 
 use utils::{
     bin_ser::BeSer,
@@ -112,6 +113,15 @@ impl From<&ImageLayer> for Summary {
 }
 
 impl Summary {
+    /// Serializes the summary header into an aligned buffer of lenth `PAGE_SZ`.
+    pub fn ser_into_page(&self) -> Result<IoBuffer, SerializeError> {
+        let mut buf = IoBufferMut::with_capacity(PAGE_SZ);
+        Self::ser_into(&self, &mut buf)?;
+        // Pad zeroes to the buffer so the length is a multiple of the alignment.
+        buf.extend_with(0, buf.capacity() - buf.len());
+        Ok(buf.freeze())
+    }
+
     pub(super) fn expected(
         tenant_id: TenantId,
         timeline_id: TimelineId,
@@ -366,11 +376,8 @@ impl ImageLayer {
 
         let new_summary = rewrite(actual_summary);
 
-        let mut buf = IoBufferMut::with_capacity(PAGE_SZ);
-        // TODO: could use smallvec here but it's a pain with Slice<T>
-        Summary::ser_into(&new_summary, &mut buf).context("serialize")?;
-        buf.extend_with(0, buf.capacity() - buf.len());
-        let (_buf, res) = file.write_all_at(buf.freeze().slice_len(), 0, ctx).await;
+        let buf = new_summary.ser_into_page().context("serialize")?;
+        let (_buf, res) = file.write_all_at(buf.slice_len(), 0, ctx).await;
         res?;
         Ok(())
     }
@@ -907,11 +914,9 @@ impl ImageLayerWriterInner {
             index_root_blk,
         };
 
-        let mut buf = IoBufferMut::with_capacity(PAGE_SZ);
-        // TODO: could use smallvec here but it's a pain with Slice<T>
-        Summary::ser_into(&summary, &mut buf)?;
-        buf.extend_with(0, buf.capacity() - buf.len());
-        let (_buf, res) = file.write_all_at(buf.freeze().slice_len(), 0, ctx).await;
+        // Writes summary at the first block (offset 0).
+        let buf = summary.ser_into_page()?;
+        let (_buf, res) = file.write_all_at(buf.slice_len(), 0, ctx).await;
         res?;
 
         let metadata = file