How can I recover data from a faulted pool?

[Volodymyr Kostyrko]

Александр Поволоцкий wrote:
> Everything is fine. The problem was in mounting order, so I did not see
> files. And I could not think properly because of tooth pain))

Yeah, maybe I hadn't pointed that out properly but you will get pool 
imported but no filesystems mounted. This can help in case when some fs 
is badly damaged and triggers assert on mount. So you will still need to 
mount required fs by hand.

>
>
> 15.07.2017 16:52, Volodymyr Kostyrko пишет:
>> Александр Поволоцкий wrote:
>>> Hello
>>>
>>> FreeBSD 10.3. ZFS.
>>>
>>>  # zpool status
>>>   pool: database
>>>  state: UNAVAIL
>>> status: One or more devices are faulted in response to persistent
>>> errors.  There are insufficient replicas for the pool to
>>>         continue functioning.
>>> action: Destroy and re-create the pool from a backup source. Manually
>>> marking the device
>>>         repaired using 'zpool clear' may allow some data to be
>>> recovered.
>>>   scan: none requested
>>> config:
>>>
>>>         NAME               STATE     READ WRITE CKSUM
>>>         database           UNAVAIL      0     0     0
>>>           mirror-0         UNAVAIL      0     0     0
>>>             gpt/database0  FAULTED      0     0     0  too many errors
>>>             gpt/database1  FAULTED      0     0     0  too many errors
>>>
>>> disks can be read, can I somehow recover data from the pool?
>>
>> For sure... First please describe what happened to both disks and what
>> hardware you were using (chipset/controller). Please don't try to
>> `zpool clear` yet.
>>
>> 1. ZFS *HEAVILY* relies on hardware to be stable, any hardware
>> glitches may result in severe pool corruption. If you have any doubts
>> in hardware first move the disks to the trusted box.
>>
>> 2. I assume both mirror parts were on different disks? ZFS doesn't
>> like pools that have more then one chunk on any drive.
>>
>> 3. Try mounting pool R/O with transaction recovery. While this is
>> mirror please do this for both disks and give it another try for
>> single disks as results may differ:
>>
>> `zpool import -N -O readonly=on -f -R /mnt/somezpoool …`
>>
>> You can use mfsBSD for that.
>>
>> If that doesn't help try:
>>
>> `zpool import -N -O readonly=on -f -R /mnt/somezpoool -Fn …`
>>
>> Both commands will try to import the pool without mounting file
>> systems in r/o mode. If that would work, try mounting only required
>> filesystem and copy some data from it.
>>
>> Please post your results.
>>
>
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