NTFS cluster size recommendation

[AlexL]

Is there a recommendation on the NTFS cluster size to use? I'm using 6.1 with a local/iSCSI repository on a NAS.

[dellock6]

Hi Alex, you mean the cluster size to be used in the storage to be used as local repository for Veeam backups? Interesting question, I never thought really about this issue, always used the default block size used by NTFS during first format. Do not know if changing the block size can increase backup performances.

Luca.

[AlexL]

defaults are not always the best, for block based SAN like our old EMC CX3-20 it's best to follow vendor guidelines, the seem to recommend 8K instead of the default 4K. For SQL or Exchange it's better to use 32K or even 64K. But I digress, I've done an initial format at 64K thinking that if VEEAM uses 1MB blocks for local storage I might as well use the largest cluster size. And no worries about slack either with the huge backup files.

Still, I'd like VEEAM to make an "official" statement regarding NTFS cluster size.

PS.. we use reverse incrementals with weekly transforms, perhaps that has special of different specs than normal daily backups

[dellock6]

Uhm, I do not think job types have specific block size configuration, since compression level and target type are configured anyway, regardless the kind of job you choose.

Luca.

[Vitaliy S.]

There are no NTFS cluster size recommendations you should follow for the backup repository servers. I would recommend using the default values.

[joergr]

Correct, leave it at default. Please also read http://www.tomshardware.co.uk/forum/267 ... ance-gains

Best regards,
Joerg

[m.novelli]

Hi guys, I would like to resurrect this thread talking about RAID cluster size for Veeam Backup repository

Generally I use Dell servers with H700 or H710 controllers and 2 TB SATA disks in RAID5 configuration. When configuring the RAID generally I use 512 KB or 1 MB cluster size, leaving later the NTFS cluster size at default Windows settings

What do you think? I use big cluster sizes at RAID level just because it seems right to me, but I've never studied deeper about that topic

Cheers

Marco

[dellock6]

Hi Marco,
for best performances you should align the raid cluster size to the file system you are going to use or a multiple of it to avoid unalignment. This is no more a problem from 2008 and above, since it rounds alignment with the initial 1024 kb block.

NTFS default is 4 kb , but only up to 16 Tb (2^64 clusters). Above it, you need to use larger blocks, up to the maximum of 64 kb. If the volume is dedicated to Veeam backups, you can also use a larger block size; you are not going to waste partially written blocks, since all files will be way larger than that value.
Honestly, I never did estensive tests on this configuration, but for Veeam backup storage I used 64kb raid blocks and 64kb NTFS blocks as a best practice, but I say it again with no validation by numbers. I would suspect performance increase would be anyway smaller if compared to other components as controller cache, ram, and compression/deduplication levels.

Luca.