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Re: mdadm, partitioned array



On Mon, Oct 08, 2007 at 04:42:51PM -0700, michael@estone.ca wrote:
> 
> I created raid 5 array via the following:
> 
> # mdadm -C /dev/md_d0 -l5 -n 6 /dev/sd[a-f]3 --auto=p
> 
> Upon reboot, I cfdisk'd the md_d0 into md_d0p1 and md_d0p2
> Formatted each partition and mounted one to /mnt and the other to /mnt2.
> 
> Running some bonnie++ benchmarks gave extra slow write results on  
> /dev/md_d0p1.
> but the same tests on /dev/md_d0p2 are normal. Read results are approx  
> the same on both partitions, but only writes are half as fast on p1  
> then p2.
> 
> I'm not quite sure why I'm getting these results. Any ideas to
> what could be wrong, or what to look for?

Well, its raid5 which is slow to begin with.  Have you verified with
mdadm that the array is complete and not running in degraded mode (which
would slow it down further)?  

Tell us about sd[a-f].  What are they and how are they connected to the
computer?  Is it bus contention?

Doug.



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