Tracy R Reed wrote: > Dexter Filmore wrote: >> Well... that Google report hands misunderstandings on a plate, alone >> about how temperature affects disk life. > > Have you done a study over thousands of drives like they have? Why > should we believe you over google who actually has data? > >> In general one would think an array of cheap disks would provide more >> security since one failed disk in a raid5 can be replaced and all is >> well again, and that's just the point: this only works when you _know_ >> a disk failed and from my experience some ATA drives don't even >> recognize if you stab them in the eye, chop off a leg and kick them >> square in the balls. > > To help with this I have smartd do a short test on each disk every day > and a long test every Sunday morning. I haven't had it find any errors > yet but I do whatever I can to exercise the disk thoroughly. SMART isn't > perfect but it is better than nothing and there is a group over at UCSD > doing research to make it better. > >> (On another note I noticed that RAID has it tripwires elsewere and >> linux software raid particularly blows chunks big style. Check your >> disk for bad block regularly or you're in for a surprise when the day >> come you really need to resync.) > > I have had very good success with Linux software RAID. I have had many > disks fail under it over the years and never lost data. One thing that > the CMU paper tells us is that RAID 5 isn't as reliable as we would > think. There is a much greater chance of a double disk failure than we > would expect.
I would like to add a reminder that there are lots of horror stories about somebody pulling the wrong disk when trying to repair a degraded raid5. Oops, now it's failed. :-( If you don't have a slot which you can use to add a hot spare, then BE VERY VERY CAREFUL! And what you say about not being able to detect a bad disk > has merit here. If we have a disk failing but don't know it and then > have another disk fail which we do find out about we will have a big > problem when we replace the failed disk we do know about and try to > rebuild. With a mirror setup the changes of this are less likely. This > combined with RAID 5's inherent performance problems and I always go > with mirroring these days. > Regards, ..jim -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
