Why everyone should be using ZFS

It is at times like these that I'm glad I use ZFS at home.


  pool: tank
 state: ONLINE
status: One or more devices has experienced an unrecoverable error.  An
        attempt was made to correct the error.  Applications are unaffected.
action: Determine if the device needs to be replaced, and clear the errors
        using 'zpool clear' or replace the device with 'zpool replace'.
   see: http://www.sun.com/msg/ZFS-8000-9P
 scrub: none requested
config:

        NAME           STATE     READ WRITE CKSUM
        tank           ONLINE       0     0     0
          mirror       ONLINE       0     0     0
            c20t0d0s7  ONLINE       6     0     4
            c21t0d0s7  ONLINE       0     0     0
          mirror       ONLINE       0     0     0
            c21t1d0    ONLINE       0     0     0
            c20t1d0    ONLINE       0     0     0

errors: No known data errors
: pearson FSS 14 $; 

The drive with the errors was also throwing up errors that iostat could report and from it's performance was trying heroicially to give me back data. However it had failed. It's performance was terrible and then it failed to give the right data on 4 occasions. Anyother file system would, if that was user data, just had deliviered it to the user without warning. That bad data could then propergate from there on, probably into my backups. There is certainly no good that could come from that. However ZFS detected and corrected the errors.


Now I have offlined the disk the performance of the system is better but I have no redundancy until the new disk I have just ordered arriaves. Now time to check out Seagate's warranty return system.

Comments:

I love that about ZFS. I've noticed, however, if you don't have many spindles (5-6) in your pool, that a single disk failure can cause iSCSI and NFS based vms to crash, as I imagine IOPS drops down below an acceptable level.

However, I've only seen this during times with heavy IO (2 - 3 vms running a build on an ESXi server using ZFS as its datastore over NFS or iSCSI.)

Seagate seems to have lowered the warranty length on most drives to 3 years. I've also noticed that when you send in a drive for replacement, they'll send you back a refurbished drive, and I've even had those fail quickly. Hopefully, it was just bad luck.

Posted by Nicholas Basila on May 26, 2009 at 04:53 PM BST #

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This is the old blog of Chris Gerhard. It has mostly moved to http://chrisgerhard.wordpress.com

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