On 09/04/2009 05:21 PM, Mark Lord wrote:
Ric Wheeler wrote:
..
You must disable the write cache on these commodity drives *if* the
MD RAID level does not support barriers properly.
..
Rather than further trying to cripple Linux on the notebook,
(it's bad enough already)..
People using MD on notebooks (not sure there are that many using RAID5
MD) could leave their write cache enabled.
How about instead, *fixing* the MD layer to properly support barriers?
That would be far more useful, productive, and better for end-users.
Cheers
Fixing MD would be great - not sure that it would end up still faster
(look at md1 devices with working barriers with compared to md1 with
write cache disabled).
In the mean time, if you are using MD to make your data more reliable, I
would still strongly urge you to disable the write cache when you see
"barriers disabled" messages spit out in /var/log/messages :-)
ric
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