XFS over LVM over md RAID

[Michael Monnerie]

On Freitag, 10. September 2010 Richard Scobie wrote:
> Limited testing using dd and bonnie++ shows no difference in write 
> performance
 
For dd it should always show the same, as you just sequentially write a 
large file. Only with bonnie you would see differences due to stripe 
sets, as the speed only drops when doing I/O not on boundaries and/or 
smaller than the stripe size, as the stripe size is the smallest 
possible I/O for the RAID.

I don't know why you don't see any difference with bonnie though.

FWIW, a stripe set of 256k means you do read/write 256k from a single 
drive on each I/O, then the next 256k from the next drive. I hope you 
have very few small accesses and mostly very large files. If you'd use a 
database on that system it would crawl...

-- 
mit freundlichen Grüssen,
Michael Monnerie, Ing. BSc

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