VMware released new builds for vCenter and ESXi 5.5 today. The builds contain mostly bug fixes, but I wanted to point out one fix that had affected those who use CBT as part of their VM backup strategy. Veeam users where initially affected by the bug…though Veeam released a work around in subsequent Veeam 8 builds this ESXi patch officially fixes the issue.

When you use backup software that uses the Virtual Disk Development Kit (VDDK) API call QueryChangedDiskAreas(), the list of allocated disk sectors returned might be incorrect and incremental backups might appear to be corrupt or missing. A message similar to the following is written to vmware.log:

DISKLIB-CTK: Resized change tracking block size from XXX to YYY

For more information, see KB 2090639.

There are also a couple of other interesting fixes in the build:

• Storage vMotion of thin provisioned virtual machine disk (VMDK) takes longer than the Lazy Zeroed Thick (LZT) disk.
• When a quiesced snapshot is created on a Windows Server 2003, Windows Server 2003 R2, Windows Server 2008, Windows Server 2008 R2, or a Windows Server 2012 virtual machine, duplicate disks might be created in the virtual machine.
• On an ESXi 5.5 host, the NFS volumes might not restore after the host reboots. This issue occurs if there is a delay in resolving the NFS server host name to IP address.

For those who backup VMs with disks larger that 128GB I would be looking to deploy this patch ASAP.