Feature request:ReFS 3 without Align backup file data blocks

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Feature request:ReFS 3 without Align backup file data blocks

Veeam Logoby jb238 » Thu Feb 16, 2017 3:00 pm

I'd like the checkbox "Align backup file data blocks" to be user configurable even with ReFS 3. Preferably in GUI but possibly with a registry key.

The block aligning costs 10% space penalty (with 64K blocks) and is necessary for Fast Clone. There are situations where ReFS3 makes sense (checksumming, auto repair with Storage Spaces, scalability) but using Fast Clone does not. Fast Clone tends to badly fragment the disk, which negatively affects restore performance and also copy performance (e.g. to external USB disk). Backup servers tend to have few big disks, which results in large capacity but poor IOPS. Preventing the disks from getting fragmented helps as does minimizing the random IOs.

I use weekly active full backups with incremental. Additionally daily backup copies with monthly full and "Read the entire restore point from source backup" checked. This gives me sequential file operations with very few random IOs. It also results in very little fragmentation. So I use ReFS for the checksumming, do not use Fast Clone, but still pay the 10% penalty.
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby Andreas Neufert » Thu Feb 16, 2017 10:53 pm

There is a way to disable block cloning if you like.
HKEY_LOCAL_MACHINE\SOFTWARE\Veeam\Veeam Backup and Replication\
RefsVirtualSyntheticDisabled
Type: REG_DWORD (0 False, 1 True)
Default value: 0
Description: By default, Veeam Backup & Replication uses Fast Clone for all backup repositories that meet the specified requirements. You can disable this option with this value.
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby Gostev » Fri Feb 17, 2017 1:30 am

We have a registry for everything that there is even a slightest chance someone may want to disable ;)
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby jb238 » Sat Feb 18, 2017 8:06 am

Yes, there is a registry key to disable fast cloning. However there is no way to disable "Align backup file data blocks" if the file system is ReFS3. I opened a case with Veeam and was told this.
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby Gostev » Sat Feb 18, 2017 1:41 pm

That is not correct. This particular setting is stored in the configuration database (as a part of other job settings) and can be easily modified by support. UI has this check box disabled, but it does not mean they cannot change it directly in the database for the given job.
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby v.Eremin » Sun Feb 19, 2017 2:30 pm

Alternatively you try to change this setting via PowerShell (it might not necessarily have the given limitation):

Code: Select all
Asnp VeeamPSSnapin
$Repository = Get-VBRBackupRepository -name "Name of your Repository"
Set-VBRBackupRepository -Repository $Repository -AlignDataBlocks:$False

Thanks.
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby jb238 » Tue Feb 21, 2017 8:34 am

Thanks for the feedback. I tried
Code: Select all
$Repository = Get-VBRBackupRepository -name "Copy"
Set-VBRBackupRepository -Repository $Repository -AlignDataBlocks:$False

but got an error:
Code: Select all
Set-VBRBackupRepository : Unable to change data block aligment settings. ReFS repository is used as a repository
At line:1 char:1
+ Set-VBRBackupRepository -Repository $Repository -AlignDataBlocks:$Fal ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [Set-VBRBackupRepository], Exception
    + FullyQualifiedErrorId : System.Exception,Veeam.Backup.PowerShell.Cmdlets.SetVBRBackupRepository
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby Gostev » Tue Feb 21, 2017 2:28 pm

So it's properly blocked in PowerShell as well - good job by QC ;)
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby Deon » Tue Feb 21, 2017 2:50 pm 1 person likes this post

Dear Gostev, can we rely on your experience that this change will be harmless for the production infrastructure?
There is likely a good reason why QC blocked this, and there is no official documentation that suggests that it is supported.
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby foggy » Tue Feb 21, 2017 4:27 pm 1 person likes this post

jb238 wrote:Yes, there is a registry key to disable fast cloning. However there is no way to disable "Align backup file data blocks" if the file system is ReFS3. I opened a case with Veeam and was told this.

If you disable FastClone, alignment will also be disabled.
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby Gostev » Tue Feb 21, 2017 7:58 pm

@Denis yes, it is totally safe. The code fully expects to encounter unaligned files and will work with them normally, without using block cloning functionality. There are many valid scenarios when unaligned files may appear in ReFS 3.1 repository, so this has been thoroughly tested and is fully supported.

QC made sure it is blocked in PowerShell because it is blocked in UI, with the latter implemented based on my request :D I just did not want users to be able to easily mess up block cloning without realizing they do, making the following few synthetic fulls overfill their backup repository as the result.
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby kubimike » Tue Feb 21, 2017 7:59 pm 1 person likes this post

IMHO would rather want fast disks/controller and block cloning FTW. I can do a fast clone of 11 TBs in 8 mins.
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby Gostev » Tue Feb 21, 2017 8:04 pm

Agree. Not only performance, but also disk space consumption (periodic fulls will no longer be spaceless with fast clone disabled).

So in the end, it is a simple choice of capacity vs. performance. You can buy lots of slow fat disks and then deal with fragmentation slowing them down even more by disabling fast clone (but that's OK because you have lots of capacity for those periodic fulls). Or you can buy a faster storage and don't worry about fragmentation at all (and it can be a few times smaller as you don't need those periodic fulls any longer).

Keeping in mind all the advanced stuff Veeam can do from backups, for the primary backup repository I prefer the latter - and this is what we are recommending in our reference architecture as well.
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby kubimike » Tue Feb 21, 2017 9:11 pm 1 person likes this post

cant slow disks also impact restore time? Most forget about that too
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Re: Feature request:ReFS 3 without Align backup file data bl

Veeam Logoby Deon » Tue Feb 21, 2017 9:49 pm

kubimike wrote:cant slow disks also impact restore time? Most forget about that too

@Kubimike
Indeed, especially if you consider that the restore is likely to trigger a lot of random read operations on the storage, and random read is always slower, especially if the data is deduplicated.

@Gostev
Thank you for the clarification. I am the kind of a guy who always double-checks stuff before suggesting it when I hear it from someone, even as experienced as you. I appreciate the response a lot.
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