Re: MD/RAID time out writing superblock

[Mark Lord <liml@rtr.ca>]

Mark Lord wrote:
> Tejun Heo wrote:
>> Hello,
>>
>> Mark Lord wrote:
>>> Tejun.. do we do a FLUSH CACHE before issuing a non-NCQ command ?
>>
>> Nope.
>>
>>> If not, then I think we may need to add code to do it.
>>
>> Hmm... can you explain a bit more?  That seems rather extreme to me.
> ..
> 
> You may recall that I first raised this issue about a year ago,
> when my own RAID0 array (MythTV box) started showing errors very
> similar to what Chris is reporting.
> 
> These were easily triggered by running hddtemp once every few seconds
> to log drive temperatures during Myth recording sessions.
> 
> hddtemp uses SMART commands.
> 
> The actual errors in the logs were command timeouts,
> but at this point I no longer remember which opcode was
> actually timing out.  Disabling the onboard write cache
> immediately "cured" the problem, at the expense of MUCH
> slower I/O times.
..

Speaking of which.. 

Chris:  I wonder if the errors will also vanish in your situation
by disabling the onboard write-caches in the drives ?

Eg.  hdparm -W0 /dev/sd?