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. 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.
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