On Mon, 2003-03-10 at 08:24, Massimiliano Ferrero wrote: > > ?????? RAID1 can only handle 1 failure also!! > > > > If you are a decent administrator, you'll act when a disk becomes > > flaky, or as soon as it fails. (Of course, if 2 disks go at the > > same time, you're hosed, but that's the case for RAID1 also...) > > Hmmm, probably I wasn't very clear. > What I mean here is that if you stuff an array of 10 RAID 5 disks the > chance that two disks will fail at the same time will be quite high. > Much higher than with two mirrored disks. So, statistically, a small > array is safer than a big one.
I wouldn't make a 10 member RAID5 set because, for practical purposes, it would be very difficult to spread the IO across multiple SCSI controllers. But if we needed REALLY BIG files, sure, I'd do it. (Of course, I wouldn't buy cheap drives, either. High quality drives plus a hot spare or 2 would let me sleep fine at night.) > Moreover if two disks in an array of ten fail, you will lose the content > of nine disks. If a mirrored pair fail you lose just one disk. > > I would say that the use of a spare disk is recommended in any case. ;) You know, I forgot all about hot spares! Even with a hot spare, if a 2nd drive puked before the storage controller integrated the hot spare into the RAID5 set, all would be lost. -- +---------------------------------------------------------------+ | Ron Johnson, Jr. mailto:[EMAIL PROTECTED] | | Jefferson, LA USA http://members.cox.net/ron.l.johnson | | | | Spit in one hand, and wish for peace in the other. | | Guess which is more effective... | +---------------------------------------------------------------+ -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
