vSphere 6 - Incremental backups of CBT enabled VMs

[dehlers]

Hi,

I'm testing with Backup Exec 15 the incremental backup of VMs.

The flags for "ctkEnabled" and "scsi<x>:<x>.ctkEnabled" are both set and "True", the file "*-ctk.vmdk" also exists.

There are no snapshots, the compatibility is ESXi 6.0 (VM Version 11).

The problem is that the full / incremental backups have the same size, so the incremental backups seems not to work.

Would it be possible to check whether this is a problem of VMware ?

thanks

Dirk

[jhunter1]

Hi Dirk,

I would actually start with a support ticket with Symantec. VMware provides the software development kit (SDK) that includes the CBT component to the backup vendors. It is up to the backup vendors to decide how they will implement and utilize the SDK. Each backup vendor does this differently. If Symantec's support team determines this is a vSphere issue, they should be able to work with resources at VMware to figure out the issue.

Jeff

[dehlers]

Hi Jeff,

I have a support ticket with Symantec. They ask if I had set the flags and that's all what they can do ...

The comment was "with vSphere 5.x has this worked, but vSphere 6 is new, so it seems to be a problem with VMware".

Therefore my question in the VMware community if I can check / test / log something with VMware.

thanks

Dirk

[jhunter1]

Hi Dirk,

Take a look at the vmware.log file in the directory where the rest of the VM files reside. You should see evidence of CBT activity when the backup job kicked off. For example:

2015-05-20T11:00:12.594Z| vcpu-0| I120: DISKLIB-CBT   : Initializing ESX kernel change tracking for fid 79479945.

2015-05-20T11:00:12.596Z| vcpu-0| I120: DISKLIB-CBT   : Successfuly created cbt node 4bcc489-cbt.

2015-05-20T11:00:12.596Z| vcpu-0| I120: DISKLIB-CBT   : Opening cbt node /vmfs/devices/cbt/4bcc489-cbt

I would look for error and warning messages.

This log entires above are from a VM running on vSphere 6.0 that is being backed up by VDP 6.0. CBT is working fine for this VM so I am not convinced it is a VMware issue. Since you already have a support ticket opened with Symantec, it might be good to open one with VMware Support, as well.

Jeff

[dehlers]

Hi Jeff,

this was the right note. I looked into the vmware.log and found the following error:

2015-05-20T16:42:31.124Z| vcpu-0| I120: DISKLIB-CBT   : Creating cbt node b22295c-cbt failed with error Cannot allocate memory (0xbad0014, Out of memory).

For this error is the following patch: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=211407...

Now the incremental backup works fine

thanks

Dirk

[jhunter1]

Hi Dirk,

Excellent. Nice find on the patch. My vSphere 6 environment was a fresh install, which likely explains why I was not seeing the issue. Thank you for sharing the resolution.

Jeff

[UNITRENDS_Luis]

This is a known issue affecting VMware ESXi 6.0 EP6 only. Prior releases of ESXi 6.0 are not affected.

See VMware KB 2145895