gpt show versus zfs_pool_proxy, versus unmounted volumes

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gpt show versus zfs_pool_proxy, versus unmounted volumes

Post by grahamperrin » Thu Oct 04, 2012 8:15 pm

Bye bye home directory at /dev/disk3

Code: Select all
macbookpro08-centrim:~ gjp22$ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *750.2 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2:                  Apple_HFS swap                    32.0 GB    disk0s2
   3: FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF               536.9 MB   disk0s3
   4:                  Apple_HFS spare                   671.1 MB   disk0s4
   5:          Apple_CoreStorage                         99.5 GB    disk0s5
   6:                 Apple_Boot Boot OS X               650.0 MB   disk0s6
   7:          Apple_CoreStorage                         616.3 GB   disk0s7
   8:                 Apple_Boot Boot OS X               134.2 MB   disk0s8
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS OS                     *99.2 GB    disk1
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *616.0 GB   disk2
   1:                        EFI                         209.7 MB   disk2s1
   2:                        ZFS                         615.7 GB   disk2s2
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:             zfs_pool_proxy gjp22                  *614.2 GB   disk3
macbookpro08-centrim:~ gjp22$ zfs list
NAME     USED   AVAIL   REFER  MOUNTPOINT
gjp22   338Gi   225Gi   304Gi  /Volumes/gjp22
macbookpro08-centrim:~ gjp22$ sudo gpt show /dev/disk3
Password:
       start        size  index  contents
           0  1199570944         
macbookpro08-centrim:~ gjp22$ zfs list
no datasets available
macbookpro08-centrim:~ gjp22$


That use of gpt may be not sane, but it's interesting that the pool/dataset gjp22 (in use by user gjp22 as a home directory) is gone so easily. The typical outcome is spinning wait cursors for nearly everything, including the Force Quit Applications window of loginwindow, and so I force a restart (Command-Control-power on the MacBookPro5,2 with OS X 10.8.2).

Result of sysdiagnose available privately, on request.

Should we expect more resistance from a future ZEVO or ZFS … a busy response, maybe?

(Early adoption of ZEVO in mind, this is probably mistreatment of the adoptee. "Expect the unexpected" and so on.)

Busy state

For some other types of device, business is recognised. An expected response, where a part of disk0 is for startup of an OS:

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gpt show: unable to open device '/dev/disk0': Resource busy


Cross reference

Whilst I have not reproduced a kernel panic, I assume that careless uses of gpt – maybe plus the mount weirdness described below – were contributory to the (2012.09.23) still waiting on znode … REG ZIL … mds panic that occurred on 2012-10-04.

gpt show versus unmounted volumes

Steps:

  1. use the unmountDisk verb of diskutil to unmount all volumes of a disk
  2. use gpt show for that disk.

Expected:

  • a show, nothing more.

Actual results:

  • a show, and mount of all volumes.

To me, that seems weird. A bug in the OS? (Nothing for gpt in Open Radar.)

Side note: I recall observing that weirdness during a recent screen recording, but don't know whether it was a recording for ZEVO.
grahamperrin Offline

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Better use of the gpt command

Post by grahamperrin » Mon Dec 31, 2012 3:00 am

For completeness

This post helped me to realise the mistakes in my use of the gpt command.
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Cross reference

Post by grahamperrin » Tue Jan 01, 2013 2:26 am

Ignoring for a moment the gpt aspect of this topic … 

Bye bye home directory seems to fit with bus issue after Blackmagic Disk Speed Test during backup
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