Most common performance issues you see in the field

The most common issue is too few resources for the workload

However that would describe pretty much every performance issue.

I think the more common issues involve not enough FA ports, disks or DA CPUs, probably in that order.

Symm has less control compared to clariion.As per my experience,In addition to FE ports backend allocation(IOPS) if the data access pattren is highly random.V-max gives that flexibility having to create a different disk pools.

how does having pools in Vmax help with random workload ?  If you said get EFDs ..i would agree.

Diskpools provides required number of IOPS as opposed to shared pool where it has no control what the other apps are doing.

ok and how is that different from using disk groups on DMX (albeit less flexibility). You place physical drives in disk groups and create devices out of that, you can't restripe them when you add new devices to the group as you can on Vmax but the concept of isolating workload is the same.

we did pool testing, we get batter performance in read but not much batter in write.

yes, it is different than disk groups because you cannot balance your disk groups but you can auto balance you pool.