Hi Richard,

Yes, sure. We can add that scenario.

What's been on my todo list is a ZFS troubleshooting wiki.
I've been collecting issues. Let's talk soon.

Cindy

Richard Elling wrote:
> Tom Bird wrote:
> 
>> Richard Elling wrote:
>>
>>  
>>
>>> I see no evidence that the data is or is not correct.  What we know 
>>> is that
>>> ZFS is attempting to read something and the device driver is 
>>> returning EIO.
>>> Unfortunately, EIO is a catch-all error code, so more digging to find 
>>> the
>>> root cause is needed.
>>>     
>>
>>
>> I'm currently checking the whole LUN, although as a 42TB unit this will
>> take a few hours so we'll see how that is tomorrow.
>>
>>  
>>
>>> However, I will bet a steak dinner that if this device was mirrored 
>>> to another,
>>> the pool will import just fine, with the affected device in a faulted 
>>> or degraded
>>> state.
>>>     
>>
>>
>> On any other file system though, I could probably kick off a fsck and
>> get back most of the data.  I see the argument a lot that ZFS "doesn't
>> need" a fsck utility, however I would be inclined to disagree, if not a
>> full on fsck then something that can patch it up to the point where I
>> can mount it and then get some data off or run a scrub.
>>
>>   
> 
> 
> Probably not.  fsck only repairs metadata, it does not restore or correct
> data.  If the data is gone or damaged, then there isn't much ZFS could
> do, since ZFS was not in control of the data redundancy (by default,
> ZFS metadata is redundant).
> 
> BTW, another good sanity test is to try to read the ZFS labels:
>     zdb -l /dev/rdsk/...
> 
> Cindy, I note that we don't explicitly address the case where the pool
> cannot be imported in the Troubleshooting and Data Recovery chapter
> of the ZFS administration guide. Can we put this on the todo list?
>  -- richard
> 
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