Re: Does XFS on hardware RAID5 have perfomance issues?

[Steve Lord <lord@sgi.com>]

On Thu, 2002-03-07 at 13:42, Murthy Kambhampaty wrote:
> I was reviewing the Linux-XFS FAQ to see if I can improve performance with
> XFS on hardware RAID5 (Mylex Acceleraid352 and five IBM Ultrastar 36LZX
> drives) by using an external log. The FAQ state the problem as if it is
> limited to software RAID5. Is hardware RAID5 performance similar whether the
> log is internal or external?
> 
> Thanks,
> 	Murthy

It should be. Simon Matter has done experiments with external logs on
software raid 5 and said it does not matter if the external log it on
the same spindles or not. The issue with the internal log with software
raid5 is that the alignment (or lack thereof) of the logwrites causes
invalidation of the internal cache in the raid code which is used for
parity generation.

So I do not think it should matter. Let me guess, you do not like the
performance you are getting right now.

Steve

-- 

Steve Lord                                      voice: +1-651-683-3511
Principal Engineer, Filesystem Software         email: lord@sgi.com