[zfs-discuss] cannot import 'home': I/O error Destroy and re-create the pool from a backup source

Jeff Johnson jeff.johnson at aeoncomputing.com
Thu Apr 26 11:19:53 EDT 2018


Anton,

If you get an opportunity post your findings on the integrity of the data
you are able to copy off the pool. It would be useful for future readers of
this thread to see what amount of corruption you may have encountered
(hopefully none) when performing a pool in distress.

Did you use the `zpool import -t <txg> *poolname*` method?

--Jeff

On Thu, Apr 26, 2018 at 8:12 AM, Anton Gubar'kov via zfs-discuss <
zfs-discuss at list.zfsonlinux.org> wrote:

> Chris, thank you very much for the hint! After a couple of panics, I could
> find the intact txg and import the pool rewinding it to one of the
> snapshots' txg. I'm copying the contents now. I understand that I may not
> be able to copy everything, but this is better than loosing everything.
>
> On Thu, Apr 26, 2018 at 4:03 PM Chris Siebenmann via zfs-discuss <
> zfs-discuss at list.zfsonlinux.org> wrote:
>
>> > Can I skip a complete scan in a hope to salvage some data? Maybe the
>> > data I need are not spoiled by this metadata error and are still
>> > accessible read-only? The txg 1492684 is acceptable level of data loss
>> > for me (from timeline perspective).
>>
>>  This is theoretically possible, although the result may not work and
>> may panic your machine if the problem is severe enough. There are ZFS
>> module parameters that control this behavior; based on looking at the
>> zfs-module-parameters manpage, you probably want to set both
>> spa_load_verify_metadata and spa_load_verify_data to 0. You can do
>> this after the module has loaded (but before you start the import)
>> by just doing:
>>
>>         echo 0 >/sys/module/zfs/parameters/spa_load_verify_metadata
>>         echo 0 >/sys/module/zfs/parameters/spa_load_verify_data
>>
>> It's possible that zdb can also tell you sufficient information to
>> determine which piece of metadata is corrupt, so you know what to not
>> look at once the pool is imported. I don't know enough about zdb to
>> give any suggestions on how to do this.
>>
>>         - cks
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>
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>


-- 
------------------------------
Jeff Johnson
Co-Founder
Aeon Computing

jeff.johnson at aeoncomputing.com
www.aeoncomputing.com
t: 858-412-3810 x1001   f: 858-412-3845
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High-Performance Computing / Lustre Filesystems / Scale-out Storage
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