The use of RAID 6 for pools with 1 TB or larger SATA drives is a risk mitigation recommendation.  Protecting your data is EMC's first priority.  This recommendation was easier to make with homogeneous pools, using Virtual Provisioning Ver. 1.0, when it was first promulgated.  The current revision of FAST Virtual Provisioning only supports a single RAID group level across all tiers.  It is well-understood that using RAID 6 for all tiers may not be the most efficient use of available capacity.  However, if the pool best practices are followed with regard to drive mixes, 80% or greater of the pool's total capacity will be on high-capacity SATA drives.  The recommendation to use RAID 6 provides the highest level of data protection for the great majority of user data.  A user always has to take their priorities into account when considering the recommendations in Best Practices.  Is their priority: availability, performance, or capacity utilization?  If their priority is availability, the RAID 6 recommendation applies.  If it is capacity utilization, and they believe they have sound policies and procedures for data protection in place (backups, hot spares, etc.), pursuing a RAID level 5 provisioning of FAST pools is likewise a sound decision.
i am planning to create storage pool and enable FAST with 70 disks in the pool  i am think about binding disk vertifcally across different DAE bus to gain performance, and we have 10 DAEs,  so I would like to bind 7 FC (300GB) disks FC and 7 SATA (1TB) disks as RAID 5  Do you think i should add 70 disks all at once, OR should i add 7 FC disks on BUS 0 and 7 SATA disks on BUS 1 at the time, so it will inialitse a proper RAID 5 Raid type, and after that just expand another 7FC + 7SATA vertifically on the storage pool. What options should i do?  Thanks Tao
Create FAST storage pool