You do not need to have the meta counts be even or powers of 2 with VP.  It was never a requirement for thick (traditional) volumes either, just made more of a difference because there was a direct relationship with the front-end device and the backend.   So 5 members is fine. :-D
This topic has been discussed in this forum in several threads but I'm not completely understanding the best approach to striped meta creation.  Environment: My environment will be 100% thin devices. I'll create striped metasmostly for Windows hosts, usually running MSSQL and where thsy ask usually for a small number of LUNs which vary in size from one host to the next, depending on the applications using the storage.   We're a new EMC customer and we're having some internal discussion around meta standards.  My question is about meta member count for thin devices. If I choose a standard TDEV size, like 32g for example, can I expect near linear performance increase as I increase the meta member count by 1. For example, will a 5-way meta outperform a 4-way and will a 6-way out perform a 5-way. Is there any negating impact to I/O load distribution within the array if I choose a meta member count that just fits the lun size request, whether it means a 4-way or an 11-way meta.  I'd rather not be limited by 4,8,16 because I think over time I'll be over provisioning more than I'd like. So if I have flexibility to choose meta member counts ranging from 4-16 in 1 member increments that would be desirable. Based on the other discussions in this forum I believe this is the case. Could someone confirm whether this assumption is correct.
Striped meta configurations