insufficient replicas following temporary 'split' of a LaCie

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insufficient replicas following temporary 'split' of a LaCie

Post by grahamperrin » Sun Oct 14, 2012 9:22 am

Earlier today I toyed with a disposable pool 'flakylaciebde' that uses just one drive – an old 500 GB LaCie Big Disk Extreme (300794EK). Internally, that's two 250 GB disks presented (by LaCie firmware?) as one 500 GB disk.

I wondered what would happen in response to a
    zpool offline …
command.

As far as I recall, the command was rejected – "insufficient replicas" or words to that effect. All OK so far.

Later, probably following a restart of OS X 10.8.2, I used the shift key at login time. Result:

  • no trace of the pool or the 500 GB disk
  • two 250 GB disks found by the operating system (I declined the invitation to initialise them).

ZFS aside: a comparable split occurred years ago (see How to break away from LaCie Big Disk Extreme firmware, for its two disks to appear as two instead of one? and my devices with known imperfections or suspected issues).

So I welcomed today's opportunity to experiment ruthlessly with the two 250 GB disks.

Highlights:

Code: Select all
/dev/disk4
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *250.1 GB   disk4
   1:                        EFI                         209.7 MB   disk4s1
/dev/disk5
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                                                   *250.1 GB   disk5


Code: Select all
macbookpro08-centrim:~ gjp22$ sudo zpool create -o ashift=12 splitlaciebde mirror /dev/disk4 dev/disk5
Password:
cannot open 'dev/disk5': no such device in /dev/dsk
must be a full path or shorthand device name


After disconnecting then reconnecting, the hardware and firmware were back to normal (a single 500 GB disk). However:

Code: Select all
macbookpro08-centrim:~ gjp22$ sudo zpool import
  pool: flakylaciebde
    id: 9774159268332657427
 state: UNAVAIL
status: One or more devices contains corrupted data.
action: The pool cannot be imported due to damaged devices or data.
config:

   flakylaciebde                                UNAVAIL  insufficient replicas
     GPTE_5C86D4B6-C273-46EB-8176-5DD968AE035A  UNAVAIL  corrupted data


Reportedly insufficient replicas but there never was a replica.

Terminal output, screen recording and other files at http://www.wuala.com/grahamperrin/publi ... de=gallery

Also in the mix, at the tail of the FireWire 800 bus, an old LaCie 1 TB Big Disk Extreme (300797EK) that's sometimes unknown (in System Information) until after I switch off then on. Maybe an issue with an external power supply.

I don't expect any answers or conclusions, but it's thought-provoking!
Last edited by grahamperrin on Fri Mar 29, 2013 11:46 am, edited 2 times in total.
grahamperrin Offline

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Re: insufficient replicas following temporary 'split' of a L

Post by grahamperrin » Sun Oct 14, 2012 9:54 am

Another highlight from Terminal output:

Code: Select all
/dev/disk4
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk4
   1:                        EFI                         209.7 MB   disk4s1
   2:                        ZFS                         249.7 GB   disk4s2
/dev/disk5
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:             zfs_pool_proxy                        *499.8 GB   disk5


Note, the 499.8 GB zfs_pool_proxy (disk5) where the underlying ZFS slice (disk4s2) is only 249.7 GB.

Now I wonder whether the
zpool create … mirror …
command was only partly successful … whilst the LaCie device was in its temporarily 'split' state.

Following a restart of the OS and another shift-login:

Code: Select all
macbookpro08-centrim:~ gjp22$ sudo gpt show /dev/disk4
      start       size  index  contents
          0          1         PMBR
          1          1         Pri GPT header
          2         32         Pri GPT table
         34          6         
         40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
     409640  487725344      2  GPT part - 6A898CC3-1DD2-11B2-99A6-080020736631
  488134984  488659240


Side note: gpt in OS X 10.8.2 seems to
not recognise option -r:


Code: Select all
macbookpro08-centrim:~ gjp22$ date
Sun 14 Oct 2012 15:45:23 BST
macbookpro08-centrim:~ gjp22$ uptime
15:45  up 9 mins, 2 users, load averages: 1.28 1.24 0.72
macbookpro08-centrim:~ gjp22$ sudo gpt show -r /dev/disk4
gpt: illegal option -- r
usage: gpt show [-l] device ...
macbookpro08-centrim:~ gjp22$ clear





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
/dev/disk4
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk4
   1:                        EFI                         209.7 MB   disk4s1
   2:                        ZFS                         249.7 GB   disk4s2
/dev/disk5
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:             zfs_pool_proxy flakylaciebde          *499.8 GB   disk5
macbookpro08-centrim:~ gjp22$ clear





macbookpro08-centrim:~ gjp22$ sudo gpt show /dev/disk4
      start       size  index  contents
          0          1         PMBR
          1          1         Pri GPT header
          2         32         Pri GPT table
         34          6         
         40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
     409640  487725344      2  GPT part - 6A898CC3-1DD2-11B2-99A6-080020736631
  488134984  488659240         
macbookpro08-centrim:~ gjp22$


Maybe worth mentioning: for the original pool flakylaciebde I had set copies=2
grahamperrin Offline

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Re: insufficient replicas following temporary 'split' of a L

Post by grahamperrin » Tue Oct 30, 2012 12:06 am

Don/developers: I plan to reuse this device, to repartition and lose all content. Around a week from now. Before I do so:

  • would you like me to get any additional information?
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no further action

Post by grahamperrin » Thu Nov 22, 2012 2:14 pm

No further action expected under this topic. I used Disk Utility to partition the disk, one JHFS+ volume.

(Side note: I plan to use an installer for Ubuntu to shrink that volume in connection with viewtopic.php?p=3164#p3164 – aiming to reproduce the problem with Disk Utility where (presumably) there's no ZFS on an affected disk.)
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Re: insufficient replicas following temporary 'split' of a L

Post by mk01 » Thu Nov 22, 2012 4:09 pm

gpt -r works as expected. the "-r" should be placed before "show".

macosx is behaving as expected - as always - it knows, what to do. and in cases like this (something is not correct with partitioning), macosx is taking lead without prior notice, without asking, without leaving note.

and many many times, macosx is going to screw things up. I have few bad experiences, specially with hand made partitioning (even before ZFS) - and macosx "knowing better".

mk
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Re: insufficient replicas following temporary 'split' of a L

Post by grahamperrin » Thu Nov 22, 2012 4:59 pm

In this case I don't suspect an issue with OS X. More likely an issue with the LaCie device, for the reasons given in the opening post.

Thanks for the correction to my use of gpt – yes, it now works as expected.
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