On Jul 26, 2011, at 8:03 AM, Jerome Herman wrote: > On 26/07/2011 16:58, Chuck Swiger wrote: >> On Jul 26, 2011, at 7:25 AM, Jerome Herman wrote: >>> Actually it is Raid 10 of a sort. Three first halves of the three disk >>> concatenated and mirrored on the three second half of the same drives. >> There's a significant problem right there. Not only will that configuration >> badly degrade the performance of the RAID volume, it also compromises the >> goal of redundancy which RAID-1 is supposed to provide. >> >> Regards, > > Disk are interweaved, so the performances are quite good (about 160% of a > single drive)
A six-disk RAID-10 setup ought to provide nearly 600% read performance improvement and 300% of the write performance of a single drive-- real numbers tend to be perhaps 550%/250% or so. > and the redundancy is here. Any single drive can fail, and the other two will > be there to provide data. Basically the first plesk is a-b-c, and the second > is b-c-a, so everything should be fine. Yes, if you do that you can survive a single disk failure, but the degraded performance is going to suck, and you have no chance of surviving a second disk outage. A six-disk RAID-10 volume can survive up to 3 disks failing (although it has a 20% chance of losing the RAID with a two-disk failure and a 50% chance of losing data if a third disk goes without anyone fixing things). Regards, -- -Chuck _______________________________________________ freebsd-stable@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"
