Re: getting I/O errors in super_written()...any ideas what would cause this?

[Ric Wheeler <rwheeler@redhat.com>]

On 12/03/2012 03:44 PM, Chris Friesen wrote:
> On 12/03/2012 02:22 PM, Ric Wheeler wrote:
>> On 11/28/2012 03:29 PM, Chris Friesen wrote:
>>> On 11/28/2012 02:27 PM, Mathias Burén wrote:
>>>
>>>> The drives look healthy, but am I reading that right? More than 10
>>>> self tests per hour?
>>>
>>> Yeah....we cranked it up to try and increase how frequently we see the
>>> problem.
>>>
>>> From what I understand normally it runs once a day.
>>>
>>> Chris
>>
>> Did the vendor suggest to you that running a self test on an active
>> drive would be OK? I would expect errors in this case - specifically
>> time outs....
>
> I'm not the main developer in that area, but from what I understand the code 
> has been like this for ages.  (It's entirely possible we've been lucky up till 
> now since we support limited hardware types.)
>
> The fact that you'd expect time outs is interesting--is that from the delay 
> switching from doing the self-test to doing the actual request?
>
> Is the expectation that the OS should not be sending any other commands to the 
> disk while doing the self-test?
>
> I was recently looking at the SCSI spec trying to learn a bit about this issue 
> and the section on background self-test (spc-4, section 5.15.4.3) seems to 
> indicate that a READ or WRITE command should cause the background self-test to 
> be aborted and the command to be processed within 2 seconds.  In our case it 
> doesn't seem to be aborting (at least it shows as "Completed" in smartctl)--is 
> this expected?
>
> Thanks,
> Chris

I jumped into this thread late - can you repost detail on the specific drive and 
HBA used here? In any case, it sounds like this is a better topic for the 
linux-scsi or linux-ide list where most of the low level storage people lurk :)

Ric