if this was my NX4 [IMAGE] , i would continue to use the same approach and build 4+1 and a 5+1 RGs. I don't know how you feel about RAID-6 but i would not want to use it for VM datastores ..too much write penalty. I am curious why somebody would say that 5+1 is slower than 4+1 ? You have an extra spindle in 5+1, yes you might not have a pretty 256k stripe size but for random workloads like VM datastores i hardly doubt you would notice it. That's my 2 cents [IMAGE]
I just installed another DAE (our second one) on a Celerra NX4 system.  It has 12 x 600GB 15k RPM SAS drives.  For best practices I'm trying to figure out how to carve out the storage.   On the DAE below it, I have a 6 disk RAID-5 and a 5 disk RAID-5 along with a hot spare.  I was told not too long ago that a 6 disk RAID-5 performs slower than a 5 disk RAID-5. So if I put 2 x 5 disk RAID 5's, I'm left with 2 extra disks.  What about the performance of RAID-6?  Would 2 x RAID-6's be ok, or maybe 1 RAID-6 and 1 RAID-5 and 1 hot spare?  Thoughts, opinions?
New DAE- Best practices for RAID setup