Disappointing performance of copy (MD raid + XFS)

[Kristleifur Daðason]

On Thu, Dec 10, 2009 at 12:39 AM, Asdo <asdo at shiftmail.org> wrote:
> Hi all,
>
> I'm copying a bagzillion of files (14TB) from a 26disk MD-raid 6 array to a
> 16disk MD-raid 6 array.
> Filesystems are XFS for both arrays.
> Kernel is 2.6.31 ubuntu generic-14
> Performance is very disappointing, going from 150MB/sec to 22MB/sec
> depending apparently to the size of files it encounters. 150MB/sec is when
> files are 40-80MB in size, 22MB/sec is when files are 1MB in size on
> average, and I think I have seen around 10MB/sec when they are of 500KB
> (this transfer at 10MB/sec was in parallel with another faster one however).

This may not be related, but I have had some general problems
regarding transfer rates in Ubuntu. Using a vanilla kernel seemed to
help: http://kernel.ubuntu.com/~kernel-ppa/mainline/

-- Kristleifur