[ltp] Re: system unresponsive during disk activity

[Daniel Pittman]

Marcus Better <marcus@better.se> writes:
> Marcus Better wrote:
>
>> This is an R60 with 1 GB RAM running kernel 2.6.24-rc6 (x86_64) and
>> KDE.  The problem has been around for a long time with earlier
>> kernels. The file systems are mostly XFS.
>
> Oh, yeah. I disabled the write cache due to the lack of write barriers
> on this system [1]. Will turn it on and see what happens.
>
> In the meantime, does anyone know if there are Thinkpads with write
> barriers (or good replacement hard drives)?
>
> [1] http://blog.madduck.net/geek/2006.07.18-xfs-caching

Er, the standard conditions for safely writing data to disk are that you
flush to media regularly -- either with barriers or by brute force -- or
that you have a battery backed cache to ensure that power loss doesn't
kill your data.

You might want to consider disabling the write cache if, and only if,
you are on battery and power is running low -- especially because you
will generally cripple performance with write cache disabled.


Oh, and several of the comments about the disks are inaccurate: data in
the cache will be flushed to the platter if Linux crashes; the risk is
present only if you lose power.[1]

Regards,
        Daniel

Footnotes: 
[1]  As a rule.  Variously broken ATA disks have done some crazy-stupid
     things over the years.

-- 
Daniel Pittman <daniel@cybersource.com.au>           Phone: 03 9428 6922
1/130-132 Stawell St, Richmond              Web: http://www.cyber.com.au
Cybersource: Australia's Leading Linux and Open Source Solutions Company