New Large P9 SSD - 931 GB, 1.86 TB, 3.72 TB, and 7.45 TB - what are new rules for minimum number of arms

With the new large P9 SSD announced, I have to ask, what is the recommended minimum number of drives, obviously for performance only reasons.
Our current production lpar is 7 tb, 13 - 775gb, Raid5, 2 Raid sets, 2 hot spares.

Theoretically, I could configure a new P9 with fewer SSD, various options.
The number of arms is the key question.
How many?

I was even considering combining all the LPARs DASD to one, which would increase the number of arms, then letting it host the R&D and other LPARS.
Food for thought.

18-061 -IBM Power Systems enhances I/O with mainstream 2.5-inch SAS SSDs

http://www-01.ibm.com/common/ssi/ShowDoc.wss?docURL=/common/ssi/rep_ca/1/897/ENUS118-061/index.html&lang=en&request_locale=en

Mainstream SSDs

New 931 GB, 1.86 TB, 3.72 TB, and 7.45 TB mainstream 2.5-inch SAS SSDs are introduced for POWER9 and POWER8 technology-based servers using SAS bays. These drives are supported in POWER9 and POWER8 system units (SFF-3) and in expansion drawers such as the EXP24SX attached to POWER9 and POWER8 servers (SFF-2). With their large capacity and lower cost per gigabyte, the drives can provide a very cost-effective and footprint-effective solution for many mainstream configurations. Note these drives are designed for workloads with modest write requirements, including as boot drives where SSD performance is desired. These drives are rated at 1 DWPD, meaning you can write 931 GB, 1.86 TB, 3.72 TB, or 7.45 TB to the SSD every day for five years, nearly 1.7 PB for the 931 GB SSD.

Thank You
_____
Paul Steinmetz
IBM i Systems Administrator

Pencor Services, Inc.
462 Delaware Ave
Palmerton Pa 18071

610-826-9117 work
610-826-9188 fax
610-349-0913 cell
610-377-6012 home

psteinmetz@xxxxxxxxxx
http://www.pencor.com/