Enterprise Vault 8.0 Rollover partitions - Stripe size

[EVMan]

Hi

We are setting up 500Gb partitions on our new EMC Celerra NS40G to house new rollover partitions for our Enterprise Vault environment. A cifs share will be created pointing to each filesystem. We are using a raid 6 – 12+2 disk configuration which we must use. However at the celerra level we can slice and stripe the disk as needed. We usually slice the disk (lun) and create stripes from slices as this is optimum performance for SATAII disks on an EMC Clerra.

When we stripe we have the option to select our stripe size from 32k or 64k or 128k. By default for cifs shares we are using 32k stripe sizes however as we are creating some of the filesystems specifically for EV we thought we’d ask the experts what EV would prefer for the stripe size?!

Thanks

James

[Maverik]

The different stripe sizes is something that I do not believe will ever have been tested with EV in terms of performance, therefore I think it wil be very hard for you get a definitive answer in terms of EV. In fact I think it could be one of those things wheree there is really no right or wrong answer but whatever fits best in your environment.

Can EMC provide you with any perfromance details for the differences and the pro's and con's for each?  I would then choose the best one for you and your environment.

[Liam_Finn1]

Strip size if you want to set it will depend on the size of file you will store on the disk array.

As you may know if you have a stripe size of 64K and the majority of the data stored will be smaller files lets say 10K then each file stored actually ends up reserving 64K on the disk which leads to disk wasteage. 

The difference between 4 kB and 128 kB stripe size is noticeable even if there is no pending command queue. Larger stripe sizes do in fact enable more I/O operations per second, while an increasing command queue depth also increases I/O performance. While small stripe sizes of 4 kB and 8 kB only double or triple the I/O performance at large command queue depths (16 commands and up), larger stripe sizes multiply the number of I/Os per second.

In short if you want to set it for performance and not space usage on the disk then larger Stripe is best.

If however you wish to size the stripe for space usage and not waste space on your disk then the smaller Stripe is best for you.

In my opinion seeing as most files are 128K or more then I would go with a minimum of 64K of a stripe or more, my preference is 128K

[MichelZ]

i don't believe that it matters, as cpu/memory are almost always the limiting factor in an ev install, and not the vault store storage. will you have collections enabled? then a large size is probably the best choice