On May 24, 2009, at 09:02 PM, Thomas Backman wrote: > So, I was playing around with RAID-Z and self-healing... Yet another follow-up to this. It appears that all traces of errors vanish after a reboot. So, say you have a dying disk; ZFS repairs the data for you, and you don't notice (unless you check zpool status). Then you reboot, and there's NO (easy?) way that I can tell to find out that something is wrong with your hardware! [root_at_clone ~]# zpool status test pool: test 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: scrub completed after 0h1m with 0 errors on Mon May 25 11:01:22 2009 config: NAME STATE READ WRITE CKSUM test ONLINE 0 0 0 raidz1 ONLINE 0 0 0 da1 ONLINE 0 0 0 da2 ONLINE 0 0 1 64K repaired da3 ONLINE 0 0 0 errors: No known data errors ----------- reboot ----------- [root_at_clone ~]# zpool status test pool: test state: ONLINE scrub: none requested config: NAME STATE READ WRITE CKSUM test ONLINE 0 0 0 raidz1 ONLINE 0 0 0 da1 ONLINE 0 0 0 da2 ONLINE 0 0 0 da3 ONLINE 0 0 0 errors: No known data errors [root_at_clone ~]# zpool history -i test # ... snip ... # Below is the relevant output from the scrub that found the errors: 2009-05-25.11:00:21 [internal pool scrub txg:118] func=1 mintxg=0 maxtxg=118 2009-05-25.11:00:23 zpool scrub test 2009-05-25.11:01:22 [internal pool scrub done txg:120] complete=1 Nothing there to say that it found errors, right? If there is, it should be a lot more clear. Also, root should receive automatic mails when data corruption occurs IMHO. [root_at_clone ~]# zpool scrub test # Wait a while... [root_at_clone ~]# zpool status test pool: test state: ONLINE scrub: scrub completed after 0h1m with 0 errors on Mon May 25 11:06:05 2009 config: NAME STATE READ WRITE CKSUM test ONLINE 0 0 0 raidz1 ONLINE 0 0 0 da1 ONLINE 0 0 0 da2 ONLINE 0 0 0 da3 ONLINE 0 0 0 errors: No known data errors I'm guessing this is the case in OpenSolaris as well...? In any case, it's BAD. Unless you keep checking zpool status over and over, you could have a disk "failing silently" - which defeats one of the major purposes of ZFS! Sure, auto-healing is nice, but it should tell you that it's happening, so that you can prepare to replace a disk (i.e. order a new one BEFORE it crasches bigtime). Regards, ThomasReceived on Mon May 25 2009 - 07:13:45 UTC
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