Dell 2650/PERC 3/Di with kernel > 2.6.22 and XFS

As it took me a day to find out I wanted to post my findings here too.

I got a used Dell Poweredge 2650 and (as usual) installed Gentoo on it. First I got a faulty harddisk in the RAID5 and rebuilding took like 6 hours.
So I didn’t mind slow io performance which I accounted to the rebuild in process.
Unfortunately it still didn’t get better when the rebuild was finished. Taking seconds for a simple “ls”, installing gentoo-sources took more than a hour and the like. I did all firmware bios updates until none were available anymore. Still, no dice.
Searching around the Web I stumbled about this post and this post (from the same author) which are pointing to issues with the most recent aacraid driver but no relation to XFS yet.
Nearly convinced to downgrade the kernel or at least the aacraid driver I did a search in the gentoo forums and finally found the solution.
Mounting the XFS filesystems with nobarrier brought the speed back to normal. Personally I would have never thought of that solution but it seems like the newer aacraid doesn’t report back that write-barrier is a bad idea on the PERC 3/Di.

Now up for the task to try to get OpenManage running on gentoo … lets try if and exotic approach helps.

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2 comments so far

  1. EDH on

    Nice. Thanks for posting this. I’ve been banging my head against the wall for a few days over this. Super slow performance with a Perc 3/Di on a 2650. Setting nobarrier upped my write performance from 3MB/s to 172MB/s.

    Thanks!

  2. Matth Ingersoll on

    I didn’t track it down directly, but using kernel 2.6.27.19 had the same issues with not just XFS but ext3 also (using aacraid). After doing a very stripped down version of the kernel, the ext3 performance went back to normal but XFS was still slow – nobarrier fixed it. So there seems to be more than just XFS and aacraid at work here.

    BTW, going from Debian 4.0 to 5.0 caused the problem too. Kernels went from 2.6.18 to 2.6.26


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