Disconnecting D drives

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Disconnecting D drives

Veeam Logoby wim17 » Tue Jul 04, 2017 7:30 am

Hi Forum,

In our datacenter we sometimes come across the strange thing that D drives from Domain Controller servers disconnect. This rarety usually happens just after Veeam removes the snapshot. My colleagues are urging me to open a support case with Veeam because it is obvious a Veeam bug but I think it is more of a resources problem.
Just after the removal of de snapshot the domain controller with get this error in the event log:
ID 153
The IO operation at logical block address 0x10 for Disk 1 (PDO name: \Device\0000002d) was retried.

Are there any knows cases like this? The funny thing is it will only trigger on Domain controllers.
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Re: Disconnecting D drives

Veeam Logoby wim17 » Tue Jul 04, 2017 9:25 am

Little edit. The Veeam jobs don't give any errors and provide a good back-up.
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Re: Disconnecting D drives

Veeam Logoby tdewin » Tue Jul 04, 2017 10:19 am

Are you running vsphere 5.5 or older? You might consider Backup From Storage Snapshot and/or upgrading to 6 : https://www.virtualtothecore.com/en/vsp ... hing-past/

In the end we just do a snapshot and remove it. You can see if you can emulate the problem by creating a snapshot and keep it open for the time it takes to do the backup. Then remove the snapshot and see if you get the same issue
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Re: Disconnecting D drives

Veeam Logoby wim17 » Tue Jul 04, 2017 11:21 am

Thanks for the reply.
We are usieng Hyper-V 2016 and hardware version 5 on the VM's.
I should have said Checkpoint, sorry.
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Re: Disconnecting D drives

Veeam Logoby evander » Tue Jul 04, 2017 3:07 pm

I don't believe this is related to Veeam at all but rather just your disk taking a bit of strain during a backup run, regardless of the backup vendor. I checked my Domain Controller and I have a few similar events in my logs too. Mostly its just retries that don't add up to much to worry about.
When you say your D drive is getting disconnected do you mean completely disconnected as in you lose your D drive and have to manually reconnect or just that its seems like the D drive has disconnected because of the errors messages listed above?

If possible I would suggest you migrate your AD virtual Machine to another storage platform or datastore and see if you get the same issues. Is your underlying storage good? Raid levels etc?
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Re: Disconnecting D drives

Veeam Logoby wim17 » Wed Jul 05, 2017 7:01 am

Really disconnected. We have to reboot the machines in order to get them back. The server itself is still running but with a lot of errors, after the reboot they work fine again. All of the servers are on a 3par that is configered by HP, we never had any troubles with it.
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Re: Disconnecting D drives

Veeam Logoby evander » Wed Jul 05, 2017 7:22 am

Ouch thats not cool. Are the C drive and D drive on different LUNS?
I use VMware rather than Hyper V so cant offer too much advise on the setup of that but is your Domain Controller doing anything other than being a Domain Controller? The weirdest thing for me is that you say it only affects the domain controllers. Are they running on a different Windows Server version to the other servers? I'm thinking the retry value is different on them than the other servers perhaps but if they all share the same underlying infrastructure then they should all equally be affected. Pure Domain Controllers are also not very "busy" servers with large amounts of data changes so backups should be easy to complete

Does this help at all: https://community.spiceworks.com/topic/1484626-iscsi-drive-disconnecting-when-under-load
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Re: Disconnecting D drives

Veeam Logoby wim17 » Wed Jul 05, 2017 7:58 am

Thanks for the link, I will check that out.

The Domain Controllers do nothing else then the DC tasks. The Windows version is the same then on other Windows servers. The Domain Controllers are not all in the same job. We host a lot of customers on the same platform and devided the Veeam jobs by Customer, so all of the jobs have a DC, a database server, fileserver, terminal server, etc etc. Almost all of those jobs have had the problem with the DC and not with the other servers. De C: and D: are on the same storage. The problems occurs during the first backup job (so no retry).
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Re: Disconnecting D drives

Veeam Logoby vmniels » Wed Jul 05, 2017 8:22 am

You can always contact support for insight however I don't think this is related due to Veeam but a reaction of the checkpoint towards the VM (which we do create though).
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