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Backup Limitations


Commodore
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I was putting my new 2011 server build through its initially shake down testing and was surprised to find that it would not back up to my 3TB USB 3.0 drive. The storage array is 2TB, as that is all I require, and backup works fine to a 2TB USB 3.0 drive.

 

I am aware of the 2TB storage partition limit but I was obviously not expecting the backup drive to have this same limitation. Oddly, it formatted and added the 3TB as a backup drive without any warnings but after stating a backup it would error out. This same drive works great as a backup drive for my V1 WHS.

 

Is it correct that the backup drive is limited to 2TB? If not, any suggests as to why it is refusing to backup?

 

Also, since WHS 2011 apparently does not permit manual deletions of previous server backups how does one manage the backup space? A 2TB backup drive is going to fill up fast as my storage partition approaches 2TB of content. What is the server behavior when the backup drive becomes full?

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Others have reported this problem of not being able to use 3TB drives for server backups. It's been reported a couple of times over at Microsoft Connect, but Microsoft seem to be unable to reproduce the issue, and have marked the bug report as "resolved" - when I don't think it is.

 

The server backup mechanism uses the VHD format - which has a 2TB limit, so you're never going to be able to backup more than 2TB of your server using the Dashboard function in any case.

 

As for managing the server backup space, some methods using command line tools and scripts are covered in this thread. Once again, this has also been reported to Microsoft over at Microsoft Connect. That bug is still marked by Microsoft as "Active" at the moment, but personally I'm not hopeful that it will be addressed in the short term.

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You can still back up the data pool to drives larger than 2TB, correct? i.e. it's only the backup of the OS drive that's an issue.

Er - is it? You can't backup more than 2TB from your server using the Dashboard server backup function. See here. Are you saying that if you choose non-OS drives, you can backup 2TB to a backup drive that is physically greater than 2TB, but if you include the OS drive in your server backup definition, you can't? That's a new one on me...

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sorry, I was actually asking. I now get what you're saying: the builtin backup program only can do 2TB in a single backup. So, if I was to copy data from teh drive pool to an external drive, that external drive could be a lot larger than 2TB. Have I got that right?

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sorry, I was actually asking. I now get what you're saying: the builtin backup program only can do 2TB in a single backup. So, if I was to copy data from teh drive pool to an external drive, that external drive could be a lot larger than 2TB. Have I got that right?

As long as you don't add it (using the Dashboard) as a "server backup drive", then yes, that's correct. You will then see the drive listed in the "Hard Drive" section of the "Hard Drives" tab, rather than in the "Server Backup" section. However, as far as I'm aware, you still won't see the hard drive (if it's bigger than 2TB) as a single drive - I think that it will get partitioned into 2TB slices by WHS 2011. But I could be completely wrong about that - I haven't got any drives bigger than 2TB to test that with...

 

And, of course, you'll have to copy the data from the other drives in the drive pool to the external drive using something like Robocopy or SyncToy. Using the Server Backup function doesn't work in this case.

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As long as you don't add it (using the Dashboard) as a "server backup drive", then yes, that's correct. You will then see the drive listed in the "Hard Drive" section of the "Hard Drives" tab, rather than in the "Server Backup" section. However, as far as I'm aware, you still won't see the hard drive (if it's bigger than 2TB) as a single drive - I think that it will get partitioned into 2TB slices by WHS 2011. But I could be completely wrong about that - I haven't got any drives bigger than 2TB to test that with...

 

And, of course, you'll have to copy the data from the other drives in the drive pool to the external drive using something like Robocopy or SyncToy. Using the Server Backup function doesn't work in this case.

I'm basing my statements on info I've heard on the podcasts and seen in the forums, but my memory isn't what it used to be so......

From what I recall, you can have a large external RAID box and the system can see it as 1 volume. I am going to have to test this as soon as my drives finish SpinRiting, but that will be a while yet.

 

RoboCopy is my copy utility of choice; I use it now in Scheduled Tasks every day.

Edited by ikon
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Thank you for the pointer to the Connect article and I can confirm it is not resolved, at least for my WD 3TB USB 3.0 drive. I initially believed the 3TB would work for backup because the setup wizard accepted and reformatted the drive as a single 3TB partition labeled as a server backup drive. But it immediately errored out on the first backup attempt.

 

This is especially perplexing given MS claims it should work and say they have failed to reproduce the issue. However this link suggests otherwise, "At this time we can only back up to 1 single 2 TB disk." https://connect.microsoft.com/WindowsHomeServer/feedback/details/647990/backup-stopped-due-to-insufficient-disc-space-even-though-every-storage-disc-had-at-least-one-backup-disc-of-equal-or-greater-size

 

Has anyone successfully used a single drive or an array larger than 2TB for a backup drive?

Edited by Commodore
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I have an 8TB RAID volume I added through disk management. WHS2011 sees it as an 8TB volume, not multiple 2TB drives. However, I can not backup anything from that volume using the built-in backup functionality. Let me clarify - it is not limited to only 2TB of data from that 8TB volume; it will not let you backup anything from that >2TB drive.

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I have an 8TB RAID volume I added through disk management. WHS2011 sees it as an 8TB volume, not multiple 2TB drives. However, I can not backup anything from that volume using the built-in backup functionality. Let me clarify - it is not limited to only 2TB of data from that 8TB volume; it will not let you backup anything from that >2TB drive.

thanks. This lines up with what I had thought, and reassures me I will be able to use my new EX-503's without issue, since I only want to RoboCopy data to and from them.

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