diff --git a/@xen-orchestra/disk-transform/src/demo.mts b/@xen-orchestra/disk-transform/src/demo.mts
index 6968b180897..3d7fd005fc9 100644
--- a/@xen-orchestra/disk-transform/src/demo.mts
+++ b/@xen-orchestra/disk-transform/src/demo.mts
@@ -1,20 +1,20 @@
 import { getSyncedHandler } from '@xen-orchestra/fs'
-import { VhdRemote, RemoteMetadata } from './from/VhdRemote.mjs'
-import { FileAccessor } from './file-accessor/FileAccessor.mjs'
+import { VhdRemote } from './from/VhdRemote.mts'
+import { FileAccessor } from './file-accessor/FileAccessor.mts'
+import { writeVhdFileToRemote } from './to/VhdRemote.mts'
 
 async function run() {
-  const { value: handler } = await getSyncedHandler({ url: 'file:///mnt/ssd/vhdblock' })
+  const { value: handlerSource } = await getSyncedHandler({ url: 'file:///mnt/ssd/vhdblock' })
+  const { value: handlerTarget } = await getSyncedHandler({ url: 'file:///mnt/ssd/out' })
   const metadataPath = './xo-vm-backups/cbb46b48-12aa-59dc-4039-8a587fdc67d5/20230831T100000Z.json'
 
   const vhd = new VhdRemote({
-    handler: handler as FileAccessor,
+    handler: handlerSource as FileAccessor,
     metadataPath,
     diskUuid: '1282b678-cb12-4b13-ab17-7a4fdac403d8',
   })
-  const { value: iterator } = await vhd.getBlockIterator()
-  for await (const block of iterator) {
-    console.log(block)
-  }
+
+  await writeVhdFileToRemote(handlerTarget, 'out.vhd', vhd)
 }
 
 run()
diff --git a/@xen-orchestra/disk-transform/src/file-accessor/InBrowserFileAccessor.mts b/@xen-orchestra/disk-transform/src/file-accessor/InBrowserFileAccessor.mts
index 4e7008054ed..494159bd8ff 100644
--- a/@xen-orchestra/disk-transform/src/file-accessor/InBrowserFileAccessor.mts
+++ b/@xen-orchestra/disk-transform/src/file-accessor/InBrowserFileAccessor.mts
@@ -1,4 +1,4 @@
-import { FileAccessor, FileDescriptor } from './FileAccessor.mjs'
+import { FileAccessor, type FileDescriptor } from './FileAccessor.mts'
 
 // handle file access inside a form
 // to transform disks into an acceptable format from the browser
diff --git a/@xen-orchestra/disk-transform/src/file-accessor/RemoteFileAccessor.mts b/@xen-orchestra/disk-transform/src/file-accessor/RemoteFileAccessor.mts
index 7ea6cfb6428..12a8bf55d45 100644
--- a/@xen-orchestra/disk-transform/src/file-accessor/RemoteFileAccessor.mts
+++ b/@xen-orchestra/disk-transform/src/file-accessor/RemoteFileAccessor.mts
@@ -1,4 +1,4 @@
-import { FileAccessor, FileDescriptor } from './FileAccessor.mjs'
+import { FileAccessor, type FileDescriptor } from './FileAccessor.mts'
 
 export class RemoteFileAccessor extends FileAccessor {
   getSize: () => Promise<Number>
diff --git a/@xen-orchestra/disk-transform/src/from/VhdRemote.mts b/@xen-orchestra/disk-transform/src/from/VhdRemote.mts
index a52ae4f3720..7511798859d 100644
--- a/@xen-orchestra/disk-transform/src/from/VhdRemote.mts
+++ b/@xen-orchestra/disk-transform/src/from/VhdRemote.mts
@@ -1,15 +1,15 @@
 import { openVhd } from 'vhd-lib'
 import {
-  DiskBlock,
-  DiskBlockData,
+  type DiskBlock,
+  type DiskBlockData,
   DiskBlockGenerator,
-  Disposable,
+  type Disposable,
   PortableDifferencingDisk,
   PortableDiskMetadata,
-  Uuid,
-} from '../PortableDifferencingDisk.mjs'
-import { FileAccessor } from '../file-accessor/FileAccessor.mjs'
-import { dirname, join, relative } from 'path'
+  type Uuid,
+} from '../PortableDifferencingDisk.mts'
+import { type FileAccessor } from '../file-accessor/FileAccessor.mts'
+import { dirname, join } from 'path'
 
 type VhdBlock = {
   id: number
@@ -26,8 +26,9 @@ export type Vhd = {
   readHeaderAndFooter(): Promise<void>
   readBlockAllocationTable(): Promise<void>
   readBlock(index: number): Promise<VhdBlock>
-  blocks(): AsyncIterator<VhdBlock>
-  writeHeaderAndFooter(): Promise<void>
+  blocks(): AsyncGenerator<VhdBlock>
+  writeHeader(): Promise<void>
+  writeFooter(): Promise<void>
   writeBlockAllocationTable(): Promise<void>
   writeEntireBlock(block: VhdBlock): Promise<void>
 }
@@ -49,15 +50,12 @@ class VhdFileGenerator extends DiskBlockGenerator {
   }
   async *[Symbol.asyncIterator](): AsyncIterator<DiskBlock> {
     const blockIterator = this.#vhd.blocks()
-    let res: { value: VhdBlock; done?: boolean }
-    do {
-      res = await blockIterator.next(this)
-      this.consumedBlocks++
+    for await (const { id, data } of blockIterator) {
       yield {
-        index: res.value.id,
-        data: res.value.data,
+        index: id,
+        data: data,
       }
-    } while (!res.done)
+    }
   }
 }
 
diff --git a/@xen-orchestra/disk-transform/src/from/utils.mts b/@xen-orchestra/disk-transform/src/from/utils.mts
index c7accc9ff55..f87a54a4baf 100644
--- a/@xen-orchestra/disk-transform/src/from/utils.mts
+++ b/@xen-orchestra/disk-transform/src/from/utils.mts
@@ -1,4 +1,4 @@
-import { PortableDiskMetadata } from '../PortableDifferencingDisk.mjs'
+import { type PortableDiskMetadata } from '../PortableDifferencingDisk.mts'
 
 export async function getXapiMetadata(xapi: any, uuid: string): Promise<PortableDiskMetadata> {
   return Promise.resolve({
diff --git a/@xen-orchestra/disk-transform/src/to/VhdFileRemote.mts b/@xen-orchestra/disk-transform/src/to/VhdFileRemote.mts
deleted file mode 100644
index 0677977a51b..00000000000
--- a/@xen-orchestra/disk-transform/src/to/VhdFileRemote.mts
+++ /dev/null
@@ -1,32 +0,0 @@
-import { VhdFile } from 'vhd-lib'
-import { DiskBlockGenerator, PortableDifferencingDisk } from '../PortableDifferencingDisk.mjs'
-import { Disposable } from 'promise-toolbox'
-import { Vhd } from '../from/VhdRemote.mjs'
-
-async function writeVhdToRemote(targetVhd: Vhd, disk: PortableDifferencingDisk): Promise<void> {
-  return Disposable.use(disk.getBlockIterator(), async (blockIterator: DiskBlockGenerator): Promise<void> => {
-    // @todo : create header/footer from size/label/parent
-    const metada = await disk.getMetadata()
-    const bitmap = Buffer.alloc(255, 512)
-    for await (const block of blockIterator) {
-      await targetVhd.writeEntireBlock({
-        id: block.index,
-        bitmap,
-        data: block.data,
-        buffer: Buffer.concat([bitmap, block.data]),
-      })
-    }
-    await targetVhd.writeHeaderAndFooter()
-    await targetVhd.writeBlockAllocationTable()
-  })
-}
-
-export async function writeVhdFileToRemote(remote, path: string, disk: PortableDifferencingDisk) {
-  const handler = remote._handler
-  return Disposable.use(VhdFile.create(handler, path), async (vhd: Vhd) => {
-    // @todo : precompute target bat to ensure we can write the block without updating the bat at each block
-    return writeVhdToRemote(vhd, disk)
-  })
-}
-
-// @todo: vhddirectory
diff --git a/@xen-orchestra/disk-transform/src/to/VhdRemote.mts b/@xen-orchestra/disk-transform/src/to/VhdRemote.mts
new file mode 100644
index 00000000000..8581ff4c622
--- /dev/null
+++ b/@xen-orchestra/disk-transform/src/to/VhdRemote.mts
@@ -0,0 +1,52 @@
+import { VhdFile } from 'vhd-lib'
+import { DiskBlockGenerator, PortableDifferencingDisk } from '../PortableDifferencingDisk.mts'
+import { Disposable } from 'promise-toolbox'
+import { type Vhd } from '../from/VhdRemote.mts'
+import { type FileAccessor } from '../file-accessor/FileAccessor.mts'
+import { createFooter, createHeader } from 'vhd-lib/_createFooterHeader.js'
+import { unpackFooter, unpackHeader } from 'vhd-lib/Vhd/_utils.js'
+import { DISK_TYPES, FOOTER_SIZE } from 'vhd-lib/_constants.js'
+import _computeGeometryForSize from 'vhd-lib/_computeGeometryForSize.js'
+
+async function writeVhdToRemote(targetVhd: Vhd, disk: PortableDifferencingDisk): Promise<void> {
+  return Disposable.use(disk.getBlockIterator(), async (blockIterator: DiskBlockGenerator): Promise<void> => {
+    // @todo : handle differencing disk parent
+
+    const metada = await disk.getMetadata()
+    console.log('metadata', { metada })
+    targetVhd.footer = unpackFooter(
+      // length can be smaller than disk capacity due to alignment to head/cylinder/sector
+      createFooter(
+        metada.virtualSize,
+        Math.floor(Date.now() / 1000),
+        _computeGeometryForSize(metada.virtualSize),
+        FOOTER_SIZE,
+        DISK_TYPES.DYNAMIC
+      )
+    )
+    console.log('got footer ', targetVhd.footer, Math.ceil((metada.virtualSize / 2) * 1024 * 1024))
+    targetVhd.header = unpackHeader(createHeader(Math.ceil(metada.virtualSize / (2 * 1024 * 1024))))
+    const bitmap = Buffer.alloc(255, 512)
+
+    for await (const block of blockIterator) {
+      await targetVhd.writeEntireBlock({
+        id: block.index,
+        bitmap,
+        data: block.data,
+        buffer: Buffer.concat([bitmap, block.data]),
+      })
+    }
+    await targetVhd.writeFooter()
+    await targetVhd.writeHeader()
+    await targetVhd.writeBlockAllocationTable()
+  })
+}
+
+export async function writeVhdFileToRemote(handler: FileAccessor, path: string, disk: PortableDifferencingDisk) {
+  return Disposable.use(VhdFile.create(handler, path), async (vhd: Vhd) => {
+    // @todo : precompute target bat to ensure we can write the block without updating the bat at each block
+    return writeVhdToRemote(vhd, disk)
+  })
+}
+
+// @todo: vhddirectory
diff --git a/@xen-orchestra/disk-transform/tsconfig.json b/@xen-orchestra/disk-transform/tsconfig.json
index dac85e3f5db..3cce3385188 100644
--- a/@xen-orchestra/disk-transform/tsconfig.json
+++ b/@xen-orchestra/disk-transform/tsconfig.json
@@ -9,7 +9,10 @@
     "module": "NodeNext",
     "moduleResolution": "nodenext",
     "declaration": true, // Generates `.d.ts` files for type safety
-    "outDir": "dist" // Outputs compiled code to the `dist` directory
+    "outDir": "dist", // Outputs compiled code to the `dist` directory
+    "verbatimModuleSyntax": true,
+    "allowImportingTsExtensions": true,
+    "emitDeclarationOnly": true
   },
   "include": ["src/**/*"],
   "exclude": ["node_modules", "dist"]
diff --git a/packages/vhd-lib/Vhd/VhdNbd.js b/packages/vhd-lib/Vhd/VhdNbd.js
index d62865b0f5a..46261875195 100644
--- a/packages/vhd-lib/Vhd/VhdNbd.js
+++ b/packages/vhd-lib/Vhd/VhdNbd.js
@@ -85,8 +85,8 @@ exports.VhdNbd = class VhdNbd extends VhdAbstract {
 
       this.#header = unpackHeader(createHeader(Math.ceil(size / DEFAULT_BLOCK_SIZE)))
       const geometry = _computeGeometryForSize(size)
-      // changed block can only be used to compute a differencing disk
-      const diskType = DISK_TYPES.DIFFERENCING
+
+      const diskType = parentUuid !== undefined ? DISK_TYPES.DIFFERENCING : DISK_TYPES.DYNAMIC
       this.#footer = unpackFooter(createFooter(size, Math.floor(Date.now() / 1000), geometry, FOOTER_SIZE, diskType))
       this.#footer.uuid = packUuid(uuid)
       if (parentUuid) {
diff --git a/packages/vhd-lib/Vhd/_utils.js b/packages/vhd-lib/Vhd/_utils.js
index 062863792d6..c0dfe9c5f73 100644
--- a/packages/vhd-lib/Vhd/_utils.js
+++ b/packages/vhd-lib/Vhd/_utils.js
@@ -44,7 +44,7 @@ exports.BUF_BLOCK_UNUSED = BUF_BLOCK_UNUSED
  * @param {Object} footer
  * @returns {Object} the parsed header
  */
-exports.unpackHeader = (bufHeader, footer) => {
+exports.unpackHeader = (bufHeader, footer = undefined) => {
   assertChecksum('header', bufHeader, fuHeader)
 
   const header = fuHeader.unpack(bufHeader)