Reasons for Faulted Device

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Reasons for Faulted Device

Post by shuman » Sat Nov 02, 2013 12:19 am

Code: Select all
NAME                                           STATE     READ WRITE CKSUM
   zdata                                          DEGRADED     0     0     0
     mirror-0                                     DEGRADED     0     0     0
       GPTE_59D9A15C-8290-4B54-9BAC-C9D8306FD760  ONLINE       0     0     0  at disk3s2
       GPTE_1A52F1BF-D18F-4310-B304-1AF7F74CC944  FAULTED      0     4     6  too many errors
   cache
     GPTE_EA83CC80-7D3D-473F-BA31-05A061BC78C5    ONLINE       0     0     0  at disk0s4


Are there other reasons a device can become faulted other than disk errors? Bad USB cable causing the device to fall of and reconnect, bad controllers in external drive, other. . .?

I keep getting a faulted drive and I'm not sure if it's a device issue or something else.

- Chris
- Mac Mini (Late 2012), 10.8.5, 16GB memory, pool - 2 Mirrored 3TB USB 3.0 External Drives
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Re: Reasons for Faulted Device

Post by grahamperrin » Sat Nov 02, 2013 2:57 am

I'm almost certain that other reasons could include issues with cabling, and so on.

In the ZEVO support forum, probably the most eloquent post about FAULTED was by raattgift, around six months ago: viewtopic.php?p=4606#p4606

Chris, remind me please, what's your hardware there? I see your signature but there's a slight discrepancy between that, and the hardware outlined at viewtopic.php?p=1177#p1177
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Re: Reasons for Faulted Device

Post by grahamperrin » Sat Nov 02, 2013 4:22 am

Reasons

For me, last month (2013-10-13) there was an incident with a two-drive pool "after I moved one drive to gently view its base". The movement might have been during writes for Time Machine.

At one point:

Code: Select all
  pool: tall
 state: UNAVAIL
status: One or more devices are faulted in response to persistent errors.  There are insufficient replicas for the pool to
   continue functioning.
action: Destroy and re-create the pool from a backup source.  Manually marking the device
   repaired using 'zpool clear' may allow some data to be recovered.
 scan: scrub in progress since Thu Oct 10 04:54:00 2013
    2.95Ti scanned out of 3.74Ti at 22.5Mi/s, 10h12m to go
    0 repaired, 78.89% done
config:

   NAME                                         STATE     READ WRITE CKSUM
   tall                                         UNAVAIL  2.77Ki     0     0  corrupted data
     GPTE_78301A52-4AFF-4D96-8DE9-E76ABC14909C  FAULTED              1.82Ti  corrupted data  (repairing)
     GPTE_99056308-F5E2-4314-852C-4DA04732A2D0  ONLINE       0     0     0  at disk10s2

errors: 85274 data errors, use '-v' for a list


The two hard disk drives:

  • 2 TB Seagate GoFlex Desk (0x50a5) purchased around May 2011
  • 3 TB Seagate Backup+ Desk (0xa0a4) purchased in March 2013, Maplin Electronics code A83LG.

I'm away from home for a few days so I can't easily tell which one was moved. The movement was truly gentle, and the physical connections appeared good before and after the incident, but both drives are on a USB 2.0 hub; this arrangement is not ideal. Still, I didn't expect the errors to occur as a result of such gentle movement.

Side note: it was not necessary to destroy that pool. I did some rolling back, and so on, and since then the pool has been fine.
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Re: Reasons for Faulted Device

Post by shuman » Sat Nov 02, 2013 9:37 am

- Mac Mini (Late 2012), 10.8.5, 16GB memory, pool - 2 Mirrored 3TB USB 3.0 External Drives

Typically when it happens I reboot the computer and zfs automatically fixes it. This time I went ahead and performed a scrub on it.

Code: Select all
pool: zdata
 state: DEGRADED
status: One or more devices are faulted in response to persistent errors.
   Sufficient replicas exist for the pool to continue functioning in a
   degraded state.
action: Replace the faulted device, or use 'zpool clear' to mark the device
   repaired.
 scan: scrub in progress since Fri Nov  1 23:10:00 2013
    1.85Ti scanned out of 1.98Ti at 51.9Mi/s, 0h44m to go
    0 repaired, 93.36% done
config:

   NAME                                           STATE     READ WRITE CKSUM
   zdata                                          DEGRADED     0     0     0
     mirror-0                                     DEGRADED     0     0     0
       GPTE_59D9A15C-8290-4B54-9BAC-C9D8306FD760  ONLINE       0     0     0  at disk3s2
       GPTE_1A52F1BF-D18F-4310-B304-1AF7F74CC944  FAULTED      0     4     6  too many errors
   cache
     GPTE_EA83CC80-7D3D-473F-BA31-05A061BC78C5    ONLINE       0     0     0  at disk0s4


I'll see if it shows "ONLINE" after its complete.
- Mac Mini (Late 2012), 10.8.5, 16GB memory, pool - 2 Mirrored 3TB USB 3.0 External Drives
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Re: Reasons for Faulted Device

Post by ilovezfs » Sat Nov 02, 2013 9:41 am

You need to follow what it says. Either replacing the device or running zpool clear.
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Re: Reasons for Faulted Device

Post by grahamperrin » Sat Nov 02, 2013 1:22 pm

Thanks Chris.

shuman wrote:… reboot the computer and zfs automatically fixes it. …


If the errors are non-permanent (as is likely with a mirror), then the record of those errors, of state, is lost when the Mac is restarted. You might find the pool usable following the restart but I shouldn't view it as a fix.

… scrub … I'll see if it shows "ONLINE" after its complete.


I should not expect a change of state from FAULTED to ONLINE.

- Mac Mini (Late 2012) … 2 Mirrored 3TB USB 3.0 External Drives … 


Before replacement, if you're not certain that the drive alone is at fault, you could try a swap – use the suspect drive with the (presumably good) controller, power supply and USB cable that are normally with the trouble-free drive.

Also there's OS X SAT SMART Driver, which may allow S.M.A.R.T. utilities to work with the drives. If this is of interest, and if you still use the Seagate Expansion drives, then for compatibility you might find it necessary to set aside the Seagate KEXT(s).
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Re: Reasons for Faulted Device

Post by shuman » Thu Nov 07, 2013 12:35 pm

GP, thanks for the advice on the SMART monitoring. I have that working now. It appears that the crux of the issue was the external drive wall warts teetering out of the UPS hooked up under the desk. I performed a scrub, which resilvered >1 TB, and now everything is good. Sometimes I get lucky and it's just a simple thing causing the problem.

I'm thinking maybe a small dot of super glue where the wall wart comes into contact with the UPS might help prevent this in the future. How do others keep things from coming unplugged?

Chris
- Mac Mini (Late 2012), 10.8.5, 16GB memory, pool - 2 Mirrored 3TB USB 3.0 External Drives
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