Hi,

can you elaborate what you mean ?

Rainer

A helpful chap from EMC provided a fully explanation which, for reference, I include here:

o   Here I’ll talk about both block size and segment size to make sure we cover all bases.

o   I'm afraid you cannot change VNX/CLARiiON's block size (512 bytes). Each Block written out to the disk is 520 bytes in size. Of the 520 bytes, 512 bytes is used to store the actual DATA written to the block. The remaining 8 bytes per block is used by the VNX/CLARiiON to store system information, such as a timestamp, parity information, checksum data.

o   Actually to match up the block size on host or application, you may read about Stripe Size and Stripe Element. Sometimes we choose "power of two" stripe sizes (64KB, 128KB, 256KB...) to match the host's or application's block size.

o   The stripe element is the amount of contiguous data stored on a single disk of the stripe. Stripe elements are measured in 512 byte blocks or in kilobytes (KB). The default stripe element size is 128 blocks, which is 64 KB. The stripe element size is not configurable through Unisphere. The default element size has been optimized for the operating environment. Attempts to "tune" it are likely to reduce performance.

o   The stripe size is the amount of user data in a RAID group stripe. This does not include drives used for parity or mirroring. The stripe is measured in KB. It is calculated by multiplying the number of stripe disks by the stripe element size.
For example, an eight-disk RAID 1/0 has a stripe width of four, with a stripe element size of 64 KB has a stripe size of 256 KB (4 * 64 KB). A five-disk RAID 5 (4+1) with a 64 KB stripe element size also has a stripe width of 256 KB drive

Short answer is: you can't, but shouldn't need to.

Thanks for your input.

Thanks - thats what I thought.

Optimizing file systems or storage systems for block/sector size is really a relic from the old old days of just using dumb disk drives.

A modern array should optimize internally to adjust to different workloads.

Yes there are some exceptions – like avoid I/O sizes that aren’t multiple of the storage block size or bad alignment.

Using a SAS HBA card, that is possible. 

I used DELL SAS HBA on R630 but connected disk to a a MD1220 via this HBA and reformatted 520 disks as 512 and it worked.