If you have any form of write cache enabled, then beware that what you may measure is the rate at which you can write to DSS's cache rather than to the disks. Once that cache fills up, you then start measuring the disk performance (i.e. the write rate drops to whatever your RAID5 array can achieve).

It may be far more reliable to measure the disk performance using a tool like IOmeter or HD Tune as these tools do not require a local file to be read from what may be a slow local disk, instead creating the network traffic on the fly.

I'm sure you can still use MPIO, but you may need to segment your 10GB Ethernet in to VLAN's that are then split-out to physical ports on the switch. I've never tried this and have no idea whether or not DSS supports this approach.

Good luck

TFZ