problem child, eject g…grandparent, diskarbitrationd panic

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problem child, eject g…grandparent, diskarbitrationd panic

Post by grahamperrin » Sun Sep 23, 2012 11:41 am

Part of what follows may be PEBKAM, but I think it worth reporting because:

  • in three of four tests, attempted eject of the great-grandparent of a problem child resulted in a kernel panic with diskarbitrationd
  • in the other test, before I could make that attempt the system gradually ground to a halt – the feeling of olde worlde I/O errors, but no such errors were logged.

MacBookPro5,2 with 8 GB memory running OS X 10.8.2.

In brief

Focus on two pools. One pool from a disk directly connected to the frontmost USB port of the laptop:

Code: Select all
macbookpro08-centrim:~ gjp22$ zfs list | grep /Volumes/zhandy
zhandy                                    531Gi  51.3Gi   411Gi  /Volumes/zhandy
zhandy/Pocket Time Machine               50.2Gi  51.3Gi  50.2Gi  /Volumes/zhandy/Pocket Time Machine


The other pool from a disk connected to a Sitecom USB 2.0 Dock CN-022 (0x0022):

Code: Select all
macbookpro08-centrim:~ gjp22$ zfs list | grep tall
tall                                     1.76Ti  26.0Gi   440Gi  /Volumes/tall
tall/backups                              889Gi  26.0Gi  10.9Gi  /Volumes/tall/backups
tall/backups/LaCie d2 Extreme            1.83Mi  26.0Gi   680Ki  /Volumes/tall/backups/LaCie d2 Extreme
tall/backups/LaCie d2 Extreme/11G         604Ki  26.0Gi   604Ki  /Volumes/tall/backups/LaCie d2 Extreme/11G
tall/backups/LaCie d2 Extreme/12A         588Ki  26.0Gi   588Ki  /Volumes/tall/backups/LaCie d2 Extreme/12A
tall/backups/blocky                      3.31Gi  26.0Gi  3.31Gi  /Volumes/tall/backups/blocky
tall/backups/gjp22                        359Gi  26.0Gi   296Gi  /Volumes/tall/backups/gjp22
tall/backups/zhandy                       516Gi  26.0Gi   398Gi  /Volumes/tall/backups/zhandy
tall/backups/zhandy/Pocket Time Machine  52.8Gi  26.0Gi  52.8Gi  /Volumes/tall/backups/zhandy/Pocket Time Machine


Code: Select all
macbookpro08-centrim:~ gjp22$ zfs get readonly tall/backups/zhandy
NAME                 PROPERTY  VALUE   SOURCE
tall/backups/zhandy  readonly  on      local
macbookpro08-centrim:~ gjp22$ zfs get readonly tall/backups/zhandy/Pocket\ Time\ Machine
NAME                                     PROPERTY  VALUE   SOURCE
tall/backups/zhandy/Pocket Time Machine  readonly  on      local


Condensed steps to reproduce

  1. ZFS send from zhandy, received at tall/backups/zhandy – without recursion
  2. at the computer level in Finder, click the volume icon for /Volumes/tall/backups/zhandy/Pocket Time Machine
  3. Pocket Time Machine disappears
  4. eject everything that can be ejected, with the exception of tall
  5. click the eject icon for tall
  6. kernel panic.

(Possible PEBKAM: not bothering to unmount the backup of Pocket Time Machine before the non-recursive backup of its parent.)

Reference materials

2012-09-23 03-38 diskarbitrationd kernel panic
2012-09-23 11-4 forced stop of the computer
2012-09-23 12-40 diskarbitrationd kernel panic
2012-09-23 15-47 diskarbitrationd kernel panic

A bit of a mishmash in and around those folders, so I should draw attention to one screen recording alone:

  • 2012-09-23 15-36-37 screen.mov

On its timeline:

  • 15:37:52 a click, in Finder, on the affected volume
  • 15:37:57 disappearance of the volume
  • 15:38:49 mount and zfs list commands suggest that volume is still mounted
  • 15:47:07 (the final frame captured before the panic) expectation of kernel panic

– panic occurred a few moments later, when I clicked tall.

Available on request, but not in public: results of sysdiagnose.
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Re: problem child, eject g…grandparent, diskarbitrationd pan

Post by grahamperrin » Fri Sep 28, 2012 1:18 am

I have not reviewed this with 1.1.1, but here's a screenshot from when I accidentally reproduced the problem with earlier ZEVO Community Edition 1.1:

2012-09-26 08-48-51 child file system Pocket Time Machine as a folder in Disk Utility.png
2012-09-26 08-48-51 child file system Pocket Time Machine as a folder in Disk Utility.png (59.39 KiB) Viewed 77 times


Note the mount point represented as a folder in Disk Utility.

----

On that occasion I avoided kernel panic by simply shutting down – by not attempting to eject/unmount the tall volume.

I neither paid close attention to verbose shut down,
nor kept a copy of /private/var/log/com.apple.launchd/launchd-shutdown.system.log
but I assume that zfsvfs_teardown (code) took care of things in the last moments.
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review

Post by grahamperrin » Wed Nov 21, 2012 6:42 pm

grahamperrin wrote:(Possible PEBKAM: not bothering to unmount the backup of Pocket Time Machine before the non-recursive backup of its parent.)


Thanks to Patrick for the tip at viewtopic.php?p=3143#p3143

I now have more appropriate properties for both file systems in the part of the pool that I use for backups:

Code: Select all
macbookpro08-centrim:874d417 gjp22$ zfs get canmount tall/backups/zhandy
NAME                 PROPERTY  VALUE     SOURCE
tall/backups/zhandy  canmount  noauto    local
macbookpro08-centrim:874d417 gjp22$ zfs get canmount tall/backups/zhandy/Pocket\ Time\ Machine
NAME                                     PROPERTY  VALUE     SOURCE
tall/backups/zhandy/Pocket Time Machine  canmount  noauto    local


As the latter will no longer mount automatically, so I expect no future kernel panic through carelessness.

Still, I'd like the kernel to not panic in edge cases such as this.
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Re: problem child, eject g…grandparent, diskarbitrationd pan

Post by gregpan » Thu May 23, 2013 4:38 am

This is an interesting topic among these forum topics. I was glued to the monitor till I read out and understood everything from this thread.
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