Recommended best allocation unit size for repository volume?

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Recommended best allocation unit size for repository volume?

Veeam Logoby bbricker » Fri Apr 06, 2012 5:43 pm 1 person likes this post

Quick question- My VB&R server is a Win2k8R2-x64 virtual machine and I'm creating a new repository volume from a 9TB RDM disk to my SAN. What is the recommended allocation unit size when formatting the drive? 64k?

thanks!
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby Gostev » Fri Apr 06, 2012 8:12 pm 2 people like this post

Tom just recommended 64K in the adjacent thread, and I totally trust him on these sort of questions ;)
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby bbricker » Fri Apr 06, 2012 8:51 pm

But I think that was for stripe size defined in the SAN, not the allocation unit size set when formatting a partition in Windows.
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby Gostev » Fri Apr 06, 2012 9:04 pm 1 person likes this post

I believe that for best performance, NTFS allocation unit size should be the same as SAN stripe size (or be a multiple of it).
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby dellock6 » Fri Apr 06, 2012 9:53 pm 1 person likes this post

Disk alignment is one of the biggest problem when it comes to SAN performances.
Windows 2008 R2 aligns its partitions around 1024Kb blocks. As a rule of thumb, if the fraction between the upper filesystem and the underlying storage is an integer, you are ok. So, since 1024k / 64k = 16, you are good to go.
If you are going for a vmdk over a vmfs filesystem, also VMware uses 64k blocks.
Also, check best practices from your storage vendor about NTFS luns.
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby bbricker » Fri Apr 06, 2012 10:34 pm

thanks guys!
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[MERGED] Repository stripe size

Veeam Logoby nmace » Mon Oct 13, 2014 3:54 pm 1 person likes this post

I'm setting up a new repository for Veeam. The Veeam VM itself will be a VM in sphere 5.5 with locally attached storage. The VMFS block size in version 5.5 is (I believe) 1 MB. Should I make the raid volume stripe size the same? I'm assuming the NTFS volume should also be 1 MB? Or is there a reason to make the stripe or NTFS size less than the VMFS block size?
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby foggy » Tue Oct 14, 2014 2:30 pm 1 person likes this post

For RAID stripe, 256KB is typically recommended, NTFS volumes should be formatted at least with 64K clusters.

You may also find this discussion useful.
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[MERGED] Veeam Repository on DAS

Veeam Logoby bertdhont » Wed Dec 17, 2014 2:56 pm 1 person likes this post

We have bought a new DAS (HP D3600) with 12 x 4TB SAS HDD.
This DAS is connected through a HP SmartArray P421.
We will use that storage as backup repository for Veeam.

As we do incremental backups and no reversed incrementals, we will create a logical drive in RAID50.
Are there any recommendations about other parameters of that volume, such as:
    Strip Size / Full Stripe Size
    Sectors/Track

Image

And in Windows, is it a good idea to format the disk with an allocation unit size of 64K
(because it is to store only large files)

Regards,

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Re: Recommended best allocation unit size for repository vol

Veeam Logoby dellock6 » Wed Dec 17, 2014 10:20 pm 1 person likes this post

To be honest I don't know what's a full stripe in HP terms...
For stripe size, you should align it to the expected deduplication level you are willing to use:
128k for "wan" (256k original, 128k with compression on)
256k for "lan" (512k original, 256k compressed)
512k for "local" (1024k original, 512k compressed).

Also, you should use the same size for both the storage and the file system, or you can incur in write amplification problems. So, use the same value also for NTFS. On Windows 2008 and later ntfs is automatically aligned to the underlying disk, otherwise you should also check and fix alignment problem, this is usually an uderestimated problem in storage configurations but it can lead to serious performance penalties.

Then, also evaluate the raid configuration, balancing space and performances. Are you sure to go for raid50 with only 12 disks??? There are no "SAS" 4TB disks, those are simple SATA disk using a SAS interface. At 7200rpm, raid50 and raid10 will give you really different results...
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby cffit » Mon Mar 28, 2016 6:34 pm

I'm currently setting up a new VEEAM server and it will have local disk for the repository. The disks are 1.2TB 10K SAS disks. What is the optimal RAID setup for best performance on a backup repository that does incremental backups? I plan to have about 12 disks in the array.

Also, for stripe size at the array level and then OS level block size, what should I go with? I assume the larger the better? Or is 256Kb the best route?
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby Delo123 » Tue Apr 05, 2016 11:01 am

As backup files are usually gigantic go with the largest...
12 disks is a bit large for raid5, raid 10 would be best if that leaves enough space for you. If not go with raid 6 or 2 raid 5's or a raid 50 if supported...
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby dellock6 » Wed Apr 13, 2016 5:05 pm 1 person likes this post

Regardless the number of disks, I'd sty away these days from Raid5 as even a single disk is too big to be safe with just one parity. The rebuild time of a 2-4-6 TB disk is insanely long, and for that entire period you have no parity left, if anything happens there's data loss.
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby Delo123 » Mon Apr 18, 2016 6:36 am

@Luca: That is why we all have Veeam backup copies! ;)
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Re: Recommended best allocation unit size for repository vol

Veeam Logoby CPCS » Fri Apr 29, 2016 9:23 am 1 person likes this post

Hi,

i am just stumbling over the same kind of question, also with HP Array Configuration Utility

Image

dellock6 wrote:To be honest I don't know what's a full stripe in HP terms...


HP Help wrote:The stripe size is the amopunt of date that is stored on each physical drive in the array.The full stripe size is the ammount of data that the controller can read or write simultaneously on all drives in the array...


dellock6 wrote:For stripe size, you should align it to the expected deduplication level you are willing to use:
128k for "wan" (256k original, 128k with compression on)
256k for "lan" (512k original, 256k compressed)
512k for "local" (1024k original, 512k compressed).

Also, you should use the same size for both the storage and the file system, or you can incur in write amplification problems. So, use the same value also for NTFS. On Windows 2008 and later ntfs is automatically aligned to the underlying disk, otherwise you should also check and fix alignment problem, this is usually an uderestimated problem in storage configurations but it can lead to serious performance penalties.


What do you mean with "local"? The Backup Server will have local storage the repository is laying on but the vm to be backed up are running in another server room, connected via 1GBit lan with the backup server.


The Raid will be Raid5 and under that two logical drives:
  • 120GB for Windows 2008R2
  • 5,5TB for Veeam Repository

So how should it be configured for each logical drive, specially the Repository?
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