On Fri, 2002-05-24 at 14:57, Sidik Isani wrote:
> On Fri, May 24, 2002 at 10:23:22AM +0200, Seth Mos wrote:
> > [...]
> > Software raid5 will give you a much better performance. And if you make it
> > with an external log onto the raid1(hardware) device it will perform a few
> > hundred percent better then the hardware raid5 of the controller.
>
> I don't have a comparison of hardware vs. software raid, but I did
> experiment with various software raid5+XFS configurations. All tests
> were on a single 400 MHz CPU with 6 13GB IDE (old, slowwww 7 MB/sec
> drives). This is our oldest RAID... no one would let me do "experiments"
> on our newer >1TB configurations :-( We have been running the 2.4.16
> kernel with XFS.
>
> o 2.4.18+XFS-1.1 shows significant performance improvements,
> especially in copying small files (30% faster) and removing
> lots of files (300% faster.) This is with an internal log.
>
> o Switching to an external log (as raid1 on partitions of two of the
> same six disks that have the raid5) boosted small-file performance
> by another 80% or so, even compared to an internal log with the
> same 2.4.18 kernel. So, even with XFS-1.1, an external log really
> helped a lot here.
The real code to speed up raid5 internal logs is still pending here.
We found a couple of problems with it and part of it is getting
reworked. An existing filesystem will be able to use the new code.
Steve
--
Steve Lord voice: +1-651-683-3511
Principal Engineer, Filesystem Software email: lord@xxxxxxx
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