Kjell,

> > Finally, a RAID 5 array made up of 4 x 2TB 7200rpm 6gbps SAS drives
> > **smokes** a single SSD (280MB/s reads and 320MB/s writes @ 8KB and
> Q=4).
>
> Yes, but what about seeks? if you have a lot of forced write transactions the
> disk will do an awful lot of seeking... An SSD will not. There won't be a lot of
> sequential I/O for a DB, will there?

The test numbers were from the ATTO Disk Benchmark tool, which does random IO tests. So, the numbers I provided included/considered seek times.

The numbers for Crystal Disk Mark v2.2 (5 passes, 1000MB run length) are:

Local RAID0 2 x 7200 SATA HDD - Reads (MB/s)
- Sequential = 146.2
- 512K Random = 28.76
- 4K Random = .0317

Local RAID0 2 x 7200 SATA HDD - Writes (MB/s)
- Sequential = 167.6
- 512K Random = 43.66
- 4K Random = 1.283

Local SSD - Reads (MB/s)
- Sequential = 269.6
- 512K Random = 258.3
- 4K Random = 28.69

Local SSD - Writes (MB/s)
- Sequential = 215.5
- 512K Random = 211.9
- 4K Random = 49.37


Sean