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On MARCH 12, 2015 VMware released their latest version of vSphere®.  With vSphere 6.0 a long list of enhancements, improvements, and fixes were released for VMware vSphere Hypervisor, VMware virtual machines, VMware vCenter Server™, virtual storage, and virtual networking.

We at Arcserve® are very excited about this latest release and we have been busy testing all of its new features to ensure that when you upgrade to vSphere 6.0 you can continue to use Arcserve Unified Data Protection with 100% confidence.

Unfortunately during our testing our engineers uncovered a significant issue with vSphere 6.0’s implementation of Changed Block Tracking (CBT).  Fortunately we are not the only VMware partners to have found and reported this defect and VMware promptly acknowledged and issued a Knowledge Base article addressing it (2114076).

The issue occurs due to heap overflow when attempting to enable Change Block Tracking (CBT).  If a virtual machine with a large number of virtual disks reaches an upper threshold CBT fails because of heap exhaustion.  We found that this issue also occurs with multiple virtual machines with CBT enabled.

For our customers wishing to use the upcoming release of Arcserve UDP 5.0 Update 4 (scheduled to release on May 18th) in their vSphere 6.0 environments you can expect the following behavior post-update:  Arcserve UDP will attempt to use CBT to perform backups but should we fail to get CBT information due to the vSphere 6.0 defect Arcserve UDP will perform a Full Backup thus at least ensuring your data is protected.

We acknowledge that running Full Backups can increase processing time but we’ve chosen to err on the side of protecting your valuable data versus simply failing the backup. Fortunately for those customers taking advantage of our RPS deduplication feature the impact to overall storage usage should be minimal.

We believe that the implementation of our work-around to resolve this issue in Update 4 will take advantage of VMware’s patch to fix the CBT defect without requiring customers to yet again update Arcserve UDP.

We have at least one customer report to us that they received notice from VMware Tech Support that a confirmed fix for this issue will be part of an “Express Patch 2 for ESXi 6.0“.  However we have been unable to confirm this with our own VMware Support contact and an exact date for release of this patch is not known at this time.

CBT is a great feature that clearly improves the efficiency and speed of virtual machine backups.   Arcserve is dedicated to providing you with the very best data protection for VMware virtual machines.  We will continue to monitor this important issue for vSphere ESXi 6.0 and will report further as news is made available.