What is the best stripe size to use?

[TheTone]

What is the recommended strip size to use when setting up a RAID 10 array? We are using LSI MegaRaid controllers with SAS disks. We have asked VMware the same question and they reffer us to hardware vendor. LSI say to test using a higher strip size due to storing large files (VMDK). What do people on here recommend or have tested?

Our controller support 1024KB strip size but not sure what to set when creating the array.

What are people suggestions, please?

Thanks

Tony

[sflanders]

Typically, you do not need to worry about this and can take the default. What type of environment are you creating (i.e. production, performance, testing, etc) and what type fo hardware?

[TheTone]

Production environment. The SAN is Intel S5000PAL with MegaRAID 8708ELP controller.

16 X SAS disks.

So the default strip size of 64kb is recommended?

Thanks

Tony

[sflanders]

Well it is technically is vendor specific. For example:

From EMC Documentation

If -Stripe is specified, a stripe size must be entered in multiples of 8192 bytes with a recommended size of 32,768 bytes (default) for NFS and CIFS environments. A 256 KB stripe size is recommended for HighRoad environments; while RAID 3 and 64 KB stripe size are recommended for ATA-based file systems.

EMC recommends a strip size of 32 KB for all types of database workloads. The recommended default strip size for all the file systems on SAS disks is 32 KB.

Personally, I have used the default value without issue.

[TheTone]

But I thought it was best practice to use a larger stripe size when dealing with large files. So what would be the recommended setting for iSCSI with VMFS file system?

Thanks

Tony

[ebowser]

Wouldn't choosing stripe size based on your filesystem block size be best?

For example, for our arrays that have 8 drives in RAID10 (4 stripes). We format our VMFS with 2MB block size. Divide block size by # of stripes = 512K stripe size.

Each disk gets accessed exactly once per block read, provided your partitions are aligned. Seems to me like that would provide most efficient access.

Tell me if I'm wrong, but it's working well for us. 140 guests across 5 SAN boxes, 12 LUNs in all.