"Hot spare"?

Discussion in 'New to FreeNAS?' started by danzg, Aug 18, 2012.

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    danzg Newbie

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    danzg, Aug 18, 2012

    Is a "hot spare" an extra, attached disk that can automatically take over for a failed disk in the RAID ... ?

    If so, how do I set it up properly?

    Is it safe to use with FreeNAS 8.2p1? There is a warning in the docs - "Use this option with caution as there is a known bug in the current FreeBSD implementation."

    Will the system immediately replace a failed disk without user interaction?

    thanks!
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    danzg Newbie

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    danzg, Aug 18, 2012

    I found some info ...

    I did `zpool add raid-5x3 spare ada0`

    Now zpool status shows
    Code (text):
    1.   pool: raid-5x3
    2.  state: ONLINE
    3.  scrub: scrub completed after 11h45m with 0 errors on Sat Aug 18 10:34:21 2012
    4. config:
    5.  
    6.     NAME        STATE     READ WRITE CKSUM
    7.     raid-5x3    ONLINE       0     0     0
    8.       raidz1    ONLINE       0     0     0
    9.         ada1p2  ONLINE       0     0     0
    10.         ada2p2  ONLINE       0     0     0
    11.         ada4p2  ONLINE       0     0     0
    12.         ada5p2  ONLINE       0     0     0
    13.         ada3p2  ONLINE       0     0     0
    14.     spares
    15.       ada0      AVAIL  
    16.  
    Is that all? No need to format / create volume / etc .. ?
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    survive Super Moderator

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    survive, Aug 18, 2012

    Hi danzg,

    Nope, there's nothing to do. Unfortunately FreeNAS doesn't actually do hot spares, it can't detect a drive failure & automatically start a rebuild...so what you have now just means you won't have to crack the case to swap out a filed drive for a good one, you will have to crack it after to remove the failed drive and add a new spare. Useful if the system is remote or something. If you haven't gotten to far into life with the system & an redo the pool it might be a better option to recreate it as a raidz2 pool so you have the extra parity built in from the start.

    -Will
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    xic044

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    xic044, Nov 20, 2013

    Hello guys this are my doubts about hot spares in FreeNAS:

    1 - Why TrueNAS (the storage box) has hot spares if it is run by FreeNAS?
    2- A ZFS zpool has a configuration option called autoreplace and that should be used in order to activate hot spare characteristics (see Oracle's ZFS documentation http://docs.oracle.com/cd/E19253-01/819-5461/gcvdi/index.html ). Why that whould not work in FreeNAS? I don't have a spare disk in order to test...

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