weird bug with ZFS and SLOG

[Volodymyr Kostyrko]

06.12.2011 00:07, Adam Stylinski wrote:
> The worst case scenario happened to me where my dedicated SLOG decided to drop off the controller and thus prevent me from importing my pool.  I quickly upgrade to FreeBSD 9.0-RC2 after testing this scenario in a VM.  It has worked successfully in a VM, but it is not working on my hardware for whatever reason.  I rollback the pool with zpool import -F share, seems ok, files are there, finishes scrub, very little corruption.  I upgrade the pool to V28, and the fs's to v5.  I then do a:
> 	 zpool remove share 15752248745115926170
>
> 	It returns no errors and pretends like the operation worked, it even appends it to my zpool history.  However, when I do a zpool status, this is what I get:

Just a +1 from me, I have such pool also:

   pool: utwig
  state: DEGRADED
status: One or more devices has been taken offline by the administrator.
         Sufficient replicas exist for the pool to continue functioning in a
         degraded state.
action: Online the device using 'zpool online' or replace the device with
         'zpool replace'.
  scan: resilvered 73,6M in 0h0m with 0 errors on Fri Oct 28 14:37:10 2011
config:

         NAME                                            STATE     READ 
WRITE CKSUM
         utwig                                           DEGRADED     0 
     0     0
           mirror-0                                      ONLINE       0 
     0     0
             gptid/ecb17af1-9119-11df-bb0b-00304f4e6d80  ONLINE       0 
     0     0
             gptid/03aed1f5-95a3-11df-bb0b-00304f4e6d80  ONLINE       0 
     0     0
         logs
           gptid/231b9002-a4a5-11e0-a114-3f386a87752c    OFFLINE      0 
     0     0

As you see I just 'offline'd that device.

Common points:
1. Pool was created on 8.x.
2. Machine runs 8_STABLE now, pool was upgraded after log device fails 
to detach.

Other hints:
The log device can be substituted with other device yet it cannot be 
deleted anyway. If you have some spare place on the disk to create some 
small partition for log and replace missed device with such partition.

> What is going on here and how do I fix it?

Dunno why but the pool now _requires_ log device. While log device is 
not present pool should use an on-disk log and 
everything-should-work-fine TM.

-- 
Sphinx of black quartz judge my vow.