[KB2136854] There's a new CBT bug in ESXi 6

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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby Gostev » Wed Nov 25, 2015 8:45 pm 3 people like this post

All, we are testing the patch and will recommend the best "way out" based on its actual behavior (for example, I would expect the patch to automatically reset CBT for all VMs upon installation - in which case no additional steps should be required aside of deploying the patch). Stay tuned for updates. Thanks!
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[MERGED] VMWARE 6.0 CBT Bug is Fixed!

Veeam Logoby jbarrow.viracoribt » Wed Nov 25, 2015 9:56 pm 1 person likes this post

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Re: VMWARE 6.0 CBT Bug is Fixed!

Veeam Logoby dellock6 » Wed Nov 25, 2015 9:59 pm 1 person likes this post

well, with all the issues around CBT in vSphere 6.0, I'd say until the patch is tested, that VMware released a patch, not that the bug is fixed ;)
Anton already wrote in the official thread about this issue (vmware-vsphere-f24/there-s-a-new-cbt-bug-in-esxi-6-t31280-60.html#p169965) that we are testing the patch, so have a look at that thread for updated info.

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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby cerberus » Thu Nov 26, 2015 3:27 pm

That's great, thanks Veeam :) We are holding off on going to 6.0 until there is a confirmation the CBT bugfix provided by VMware is working for Veeam backups using CBT.
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby Gostev » Thu Nov 26, 2015 8:49 pm 4 people like this post

All, we have completed the first day of testing in the same exact lab and using the same heavy write I/O test that made the original issue easily reproducible. After a few TB of increments, the above-mention patch appears to fully resolve the original issue when installed on ESX 6.0 Update 1a build 3073146.

However, we found that simply installing the patch is not sufficient, and CBT reset is required for all of your VMs. This is because existing CBT map files may contain issues created earlier due to the original bug, which may result in inconsistent full backups in future. Having CBT reset will also force the following job run use "full scan" incremental pass, thus fixing any existing inconsistencies in backups and replicas, as discussed earlier in this topic.

Provided CBT reset has been performed, Active Full backups is not required.

Performing Active Full backups by itself cannot be considered as a substitute to CBT reset with this particular CBT issue.

Thanks!
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby mdmd » Thu Nov 26, 2015 9:26 pm

So that means powering off every VM and resetting the CBT ? A full active wont do? This is going to be VERY time consuming and requires a lot of out of hours work, who should I send the bill too....

VMware really have gone down hill.
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby Gostev » Thu Nov 26, 2015 9:39 pm 1 person likes this post

Did you read the KB article I have linked in my previous post? Alternative CBT reset method is fully automated and does not require VM to be powered off (in fact, it requires them to be powered on and will not process powered off ones).
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby jelloir » Thu Nov 26, 2015 10:29 pm 1 person likes this post

Gostev wrote:Alternative CBT reset method is fully automated and does not require VM to be powered off (in fact, it requires them to be powered on and will not process powered off ones).

Just ran this (ResetCBT.ps1) and all worked well.
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby Pat490 » Fri Nov 27, 2015 7:10 am

Does ESX have to be Update 1A or can I install the patch directly on Update 1 Build 3029758?
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby VladV » Fri Nov 27, 2015 9:54 am

I used this older method https://www.veeam.com/kb1940 . It processes all powered on vms with no existent snapshots.
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby mdmd » Fri Nov 27, 2015 2:58 pm

Thanks Gostev, didn't see the link, I ran the ResetCBT.ps1 and it seemed to work but I did get a wanrning in between creating and removing snapshots (it did create) I presume this isn't a problem ?

Image
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby mdmd » Fri Nov 27, 2015 3:11 pm

Also, as we are running Reverse incremental backups, I presume I don't need to run a active full backup?
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby v.Eremin » Fri Nov 27, 2015 3:28 pm

As Anton's mentioned several posts above, as long as CBT reset has been performed, Active full is not needed.

Gostev wrote:Provided CBT reset has been performed, Active Full backups is not required.
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby mdking » Sat Nov 28, 2015 8:38 am

Please excuse me if someone has already asked this. But if we are using Reverse Incremental backups and we perform the Vmware upgrades along with the CBT reset.

What happens to all of the older incremental files? Would they still be usable?

Thanks
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Re: [KB2136854] There's a new CBT bug in ESXi 6

Veeam Logoby pad343848 » Sat Nov 28, 2015 10:17 am

Guys,

After installing update on ESX and perform full active backup all issue will gone?
Or i still need to run custom script from VEEAM KB?

I would like to avoid scripts and manual job.

What option do i have ?
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