8 meta members should be enough for performance considerations with VP.  Powers of 2 were a very good idea with thick volumes but is not important for VP volumes. 

what are VP voulmes?

And for best performance, the VP (TDEVs or thin) metas should be striped.  Concatenated metas can be expanded easier, but they will have lower overall performance.

VP = Virtual provisioning volumes (thin).  You mentioned TDEVs which are VP volumes.

You will get better overall performance from striped metas.  Yes the backend is already striped, but IO to a single meta on the front-end can still restrict performance, even with 100% cached IO.

If you won't ever need to expand the meta, use striped metas.  If ease of expansion is more important than performance, use concatenated meta volumes.

As the tdevs are already striped on back end data devices, is it okay to stripe again for the metas, rather than going for concatenated Metas ?, isn't striping on striping  a issue ?, help me understand.

Thanks,

two levels of stripping accepted, like RAID5 makes the first  , striped metalun makes the second  part ad  creating a file system with striping makes the third one( we avoid the third layer of stripping) ; yes there is a little confustion on scenario like while using Oracle ASM( which again striped internally)

Too many levels of striping is a bigger concern for traditional non VP volumes.  For best performance on VP volumes you should use striped metas even though that could be the third level of striping in the Symmetrix.  (RAID =1, VP = 2 META = 3 ), they will have higher performance than a concat meta, but are harder to expand.

Quincy,

Wondering if you could provide a little more detail regarding your statement "Powers of 2 were a very good idea with thick volumes but is not important for VP volumes."

I recently read a "VMAX Blueprint" document that indicated that metas should be built based on a TDEV size range and configured using base-2 ... 2,4,8,16,32-way. I also seem to recall John Adams at EMC World saying the same thing ... build metas using base-2 ... but I could be wrong there.

So what's the final verdict? Are there best practices for meta members/sizes in VP? Can I create a meta with any number of members I wish without any issues?

Thanks!

Yup. :-)

Metas on thick provisioning have to fit into the backend, this is why the powers of 2 were important.  Since VP metas have nothing to do with the backend layout at all, there is no such need.  A 5 member meta may perform slightly better than a 4 member meta in some cases, and would be fine.  However there is nothing wrong with sticking with powers of 2, since they would also work fine.