On Thu, May 22, 2008 at 7:12 PM, Guy Boisvert <boisvert.guy at videotron.ca> wrote: > You do not need two (2) raid controllers unless you want to have > redundancy at the controller level. Adaptec, 3Ware, etc do RAID 50. > For RAID 50, you need at least 6 disks. > > http://en.wikipedia.org/wiki/RAID > > > For database, i'd go with RAID 10. As pointed out Joseph in a previous > post, RAID 5 rebuilding would slows the array down. > > As for RAID 10, i didn't make extensive benchmarks but here are the > rough results i got with Adaptec 3405 and four (4) Seagate 15K SAS drives: > > > RAID 5: Read = 170 MiB/s > Write = 135 MiB/s > > RAID 10: Read = 170 MiB/s > Write = 160 MiB/s And stick with md-raid 10 (also known as software raid) because it is much more intelligently designed than any closed-source-embedded-raid-controller. Nowadays hardware raid frightens me because of the need to have spare raid-controllers for every hardware-raid-configuration I have. They are neither interchangable nor easily recoverable. md-raid 10 can be established with any number of disks (at least 3 but better check with google)