Re: MD/RAID time out writing superblock

[Mark Lord]

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?


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