Copilot commented on code in PR #640:
URL:
https://github.com/apache/cloudstack-documentation/pull/640#discussion_r3055345747
##########
source/adminguide/virtual_machines/importing_vmware_vms_into_kvm.rst:
##########
@@ -117,6 +117,178 @@ If you are hitting the following error when running
ovftool, install the depende
dnf install libnsl
+VDDK-based Optimized Conversion
+-------------------------------
+
+CloudStack supports an optimized VMware-to-KVM migration path using virt-v2v
in vpx input mode combined with
+VMware's Virtual Disk Development Kit (VDDK). This method eliminates the OVF
export phase entirely and streams
+disk blocks directly from the source hypervisor into the conversion pipeline,
resulting in significantly faster
+migration times.
+
+The traditional OVF-based workflow operates in two sequential phases:
+
+1. Export the entire VM as OVF/VMDK files to temporary storage (full disk
copy).
+2. Convert the local VMDK files using virt-v2v (second full disk read and
write).
+
+The VDDK-based workflow replaces both phases with a single streaming pipeline:
+
+- virt-v2v connects directly to vCenter via ``vpx://``
+- Disk blocks are read on demand via VDDK (using nbdkit internally as the
translation layer between the
+ VDDK API and virt-v2v's NBD block device interface)
+- Conversion and disk transfer happen concurrently
+- Only allocated blocks are transferred; zero-filled and sparse extents are
skipped
+- No intermediate OVF or VMDK files are created
+
+This reduces disk I/O amplification, eliminates temporary staging storage, and
shortens end-to-end migration time.
+
+.. note:: CloudStack does not distribute VDDK, operators must download it
separately.
+Along with the new VDDK-based conversion method the traditional OVF-based
method remains supported for environments.
+Operators can choose the conversion method on a per-migration basis in the UI
import wizard.
+
Review Comment:
The ``.. note::`` directive at line 144 is immediately followed by
unindented text without a blank line. In reStructuredText this commonly
triggers a docutils/Sphinx warning ("Explicit markup ends without a blank
line") and the following sentences won't be part of the note. Add a blank line
after the note (and indent the following lines if they’re intended to be
included in the note block).
```suggestion
.. note::
CloudStack does not distribute VDDK, operators must download it
separately.
Along with the new VDDK-based conversion method the traditional OVF-based
method remains supported for environments.
Operators can choose the conversion method on a per-migration basis in
the UI import wizard.
```
##########
source/adminguide/virtual_machines/importing_vmware_vms_into_kvm.rst:
##########
@@ -117,6 +117,178 @@ If you are hitting the following error when running
ovftool, install the depende
dnf install libnsl
+VDDK-based Optimized Conversion
+-------------------------------
+
+CloudStack supports an optimized VMware-to-KVM migration path using virt-v2v
in vpx input mode combined with
+VMware's Virtual Disk Development Kit (VDDK). This method eliminates the OVF
export phase entirely and streams
+disk blocks directly from the source hypervisor into the conversion pipeline,
resulting in significantly faster
+migration times.
+
+The traditional OVF-based workflow operates in two sequential phases:
+
+1. Export the entire VM as OVF/VMDK files to temporary storage (full disk
copy).
+2. Convert the local VMDK files using virt-v2v (second full disk read and
write).
+
+The VDDK-based workflow replaces both phases with a single streaming pipeline:
+
+- virt-v2v connects directly to vCenter via ``vpx://``
+- Disk blocks are read on demand via VDDK (using nbdkit internally as the
translation layer between the
+ VDDK API and virt-v2v's NBD block device interface)
+- Conversion and disk transfer happen concurrently
+- Only allocated blocks are transferred; zero-filled and sparse extents are
skipped
+- No intermediate OVF or VMDK files are created
+
+This reduces disk I/O amplification, eliminates temporary staging storage, and
shortens end-to-end migration time.
+
+.. note:: CloudStack does not distribute VDDK, operators must download it
separately.
+Along with the new VDDK-based conversion method the traditional OVF-based
method remains supported for environments.
Review Comment:
Sentence reads incomplete/awkward: “the traditional OVF-based method remains
supported for environments.” Consider clarifying what environments this refers
to (e.g., “...supported for environments where VDDK cannot be used/installed”).
```suggestion
Along with the new VDDK-based conversion method, the traditional OVF-based
method remains supported for environments where VDDK cannot be used or
installed.
```
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