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Re: Running slower after raid0




On Tue, 1 Nov 2005, Ron Johnson wrote:
 
> That's why I qualified my statement with "large bits of data".

:-)
 
> > 	same for 100GB files .. to split it into 2x 50GB each
> > 	on each spindle 
> > 
> > should be a fun driver to write(if needed), config and test
> 
> Doesn't the md driver do that?  It should.  HW RAID controllers
> do it, so it can't be that difficult.  If your chunk size is
> 512KB, and your file size is 100MB (102400KB), then the file gets
> divvied up into 200 sections.  You "just" wait until enough of
> the data is in the cache, and then "parallel round-robin" the reads
> or writes.

yup...

but if your files are less than one chunk-size... does that mean
it all gets written to one disk ??

it'd be a fun experiment .. but some folks in the raid lists
concluded that with sw raid, changing chunk-size didnt affect their
performance

	- but with all benchmarks and tests, unless you know
	exactly what it's doing, most results are meaningless
	if the "environment" is not recreateable and shows
	the same results

c ya
alvin



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