Ciaran McCreesh posted <[EMAIL PROTECTED]>, excerpted below, on Sun, 20 Nov 2005 14:57:49 +0000:
> On Sun, 20 Nov 2005 07:49:11 -0700 Lares Moreau > <[EMAIL PROTECTED]> wrote: > | On Sun, 2005-11-20 at 04:29 -0700, Duncan wrote: > | > If the capacity is there, go RAID6 (dual parity RAID5, so two > | > drives can drop out without the thing dieing) with a hot-spare as > | > well, so threex146GB usable. > | > | Is RAID6 production ready? > > RAID6 was only invented because a certain large hardware manufacturer > shipped a bunch of duff disks in one of its drive arrays. In practice > it's not necessary, because if you're taking the kind of damage that > kills multiple drives over a short period then you're going to lose > more than two drives anyway. There's another advantage as well. Single disk failure is common enough to be worrying about or raid5 wouldn't be in consideration. I'm certainly no expert, but from from my research previous to installing here, it is said that raid6 in single failure mode maintains speed, while a raid5 with hot-spare would be responding far slower during the same time, as it brought the hot-spare online and did the rebuild. Thus, if one is going to bother with the hot-spare in the first place, rather than just run the raid5 in degraded mode until a spare can be procured and installed, one might as well put that hot-spare to use making the raid5 a raid6, both protecting against the corner-case of a short-period compound failure, AND maintaining speed during a simple failure. Of course, if that speed maintenance is a a critical factor, then one would hot-spare the raid6 as well, so non-degraded operation could be resumed ASAP, thus again allowing a single failure without degrading speed. -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman in http://www.linuxdevcenter.com/pub/a/linux/2004/12/22/rms_interview.html -- gentoo-dev@gentoo.org mailing list
