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On Sun, May 3, 2020 at 10:56 AM Caveman Al Toraboran < |
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toraboracaveman@××××××××××.com> wrote: |
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> |
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> On Sunday, May 3, 2020 1:23 PM, Wols Lists <antlists@××××××××××××.uk> |
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wrote: |
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> |
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> > For anything above raid 1, MAKE SURE your drives support SCT/ERC. For |
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> > example, Seagate Barracudas are very popular desktop drives, but I guess |
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> > maybe HALF of the emails asking for help recovering an array on the raid |
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> > list involve them dying ... |
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> > |
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> > (I've got two :-( but my new system - when I get it running - has |
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> > ironwolves instead.) |
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> |
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> that's very scary. |
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> |
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> just to double check: are those help emails about |
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> linux's software RAID? or is it about hardware |
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> RAIDs? |
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> |
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> the reason i ask about software vs. hardware, is |
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> because of this wiki article [1] which seems to |
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> suggest that mdadm handles error recovery by |
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> waiting for up to 30 seconds (set in |
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> /sys/block/sd*/device/timeout) after which the |
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> device is reset. |
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> |
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> am i missing something? to me it seems that [1] |
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> seems to suggest that linux software raid has a |
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> reliable way to handle the issue? since i guess |
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> all disks support resetting well? |
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> |
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> [1] https://en.wikipedia.org/wiki/Error_recovery_control#Software_RAID |
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> |
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When doing Linux RAID, hardware or software, make sure you get a RAID aware |
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drive that supports TLER (Time Limited Error Recovery) or whatever the |
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vendor that makes your drive calls it. Typically this is set at about 7 |
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seconds guaranteeing that no mater what's going on the drive will respond |
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to the upper layers (mdadm) to let it know it's alive. A non-RAID drive |
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with no TLER feature will respond when it's ready and typically if that's |
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longer than 30 seconds then the RAID subsystem kicks the drive and you have |
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to re-add it. While there's nothing 'technically' wrong with the storage |
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when the RAID rebuilds you eventually hit another on of these >30 second |
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waits and another drive gets kicked and you're dead. |
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I've used the WD Reds and WD Golds (no not sold) and never had any problem. |
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Build a RAID with a WD Green and you're in for trouble. ;-))) |
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HTH, |
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Mark |
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