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On Oct 6, 2011 9:06 PM, "Mark Knecht" <markknecht@×××××.com> wrote: |
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> |
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> On Thu, Oct 6, 2011 at 1:28 PM, Michael Mol <mikemol@×××××.com> wrote: |
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> > On Thu, Oct 6, 2011 at 4:21 PM, Mark Knecht <markknecht@×××××.com> |
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wrote: |
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> >> On Thu, Oct 6, 2011 at 1:03 PM, Paul Hartman |
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> >> My worry was that if the mdraid daemon saw one drive gone - either |
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> >> when starting to spin down or when one spins up slowly - and if mdraid |
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> >> didn't understand that all this stuff was taking place intentionally |
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> >> then it might mark that drive as having failed. |
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> > |
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> > Does mdraid even have an awareness of timeouts, or does it leave that |
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> > to lower drivers? I think the latter condition is more likely. |
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> > |
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> > I suspect, though, that if your disk fails to spin up reasonably |
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> > quickly, it's already failed. |
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> > |
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> |
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> In general I agree. However drives that are designed for RAID have a |
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> feature known as Time Limited Error Recovery (TLER) which supposedly |
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> guarantees that they'll get the drive back to responding fast enough |
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> to not have it marked as failed in the RAID array: |
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> |
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> http://en.wikipedia.org/wiki/Time-Limited_Error_Recovery |
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> |
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> When I built my first RAID I bought some WD 1TB green drives, built |
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> the RAID and immediately had drives failing because they didn't have |
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> this sort of feature. I replaced them with RAID Edition drives that |
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> have the TLER feature and have never had a problem since. (Well, I |
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> actually bought all new drives and kept the six 1TB drives which I'd |
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> mostly used up for other things like external eSATA backup drives, |
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> etc...) |
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> |
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> Anyway, I'm possibly over sensitized to this sort of timing problem |
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> specifically in a RAID which is why I asked the question of Paul in |
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> the first place. |
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|
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My first RAID was with three Seagate economy 1.5TB drives in RAID 5, shortly |
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followed by three 1TB WD black drives in RAID 0. I never had the problems |
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you describe, though I rebuit the RAID5 several times as I was figuring |
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things out. (the 3TB RAID0 was for some heavy duty scratch space.) |
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