ide/ata write caching safe now?
fedora at workingwithit.com
Thu Dec 7 07:05:47 UTC 2006
Bruno Wolff III wrote:
> For the last several years I have had write caching disabled on my ide/ata
> hard drives for safety, but recently I have been seeing information that
> suggests I might be able to enable it safely now. I use ext3 file systems
> on raid 1 arrays (using md). Based on information I have seen, it looks like
> since kernel 2.6.15 everything should be in place to allow enabling write
> caching to be safely enabled if I use the barrier=1 option when mounting the
> file systems. That option doesn't show up in the man page for mount on fc5, but
> does seem to be recognized.
> Is this correct, or should I continue to keep the write cache disabled?
I know that recently I discovered that Western Digital JS series hard
disks don't play ball with the onboard RAID controller, when a failure
occurs the drives write recovery goes nuts and the container fails.
Seagate doesn't have this problem.
I'd don't know enough about the Software RAID interaction with the
drives write recovery, but I'd guess that it would probably work. Last
time I used software RAID (about 3 years back, with Seagate disks) I
didn't need to disable the write cache. I was using a combination of
RAID 1 and RAID 5 in the config and everything seemed to work. However,
this is by no means a guarantee your config won't spit the dummy. I'd
advise you do a backup to some other media before you try.
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