tony.turner (5/2/2012)
Sounds suspiciously like your hosting company has been listening to their EMC salesperson. EMC apparently is strongly in favour of RAID 5 for SSD, thus the loss of a single disk in the array. The EMC claim is that RAID 5 on SSD has a minimal write latency effect. Not convinced from measurements in practice
My own tests of locally attached 6 drive (enterprise) SATA SSD's vs. 10 drive 15k FC SAN disks shows that the 6 disk local SATA RAID 5 is always faster; even for 8KB random writes the 6 SSD RAID 5 is near triple the performance of the 10 disk RAID 10, though for 64KB random writes it's only about a third better. For most other categories the SSD RAID 5 is very much faster, though I was limited to 4Gbps throughput on the SAN in my tests, which is an artificial throughput ceiling.
SQLIO, at least, also shows average and max latencies to be much better for the local SSD's than for the SAN.