Raid 5 performance

[Martin Duclos]

I'm using software raid.

The question is not really about what hardware configuration will make it 
better, rather, I want to know where to look to get nubmers. I want to know 
if the io is the bottleneck or if the cpu is the bottleneck. I'm not really 
interested in changing my setup. I am just curious as to ways I can monitor 
performance of that system in particular. BTW I have 4 ide controller as in 
a seperate cable for every drive.

Martin


Hardware or software raid?  raid5 is one of the processing heavy (mainly
xor) raid implementations, so you will have some performance impact if
you run software raid.  The software raid code in the kernel does have
mmx and sse code paths to speed up the calculations onf machines which
have those instruction sets, which a P120 of course does not.

Adding ram shouldn't make any difference to the raid, while a faster CPU
would make a difference if using software raid.

With hardware raid the card does the xor calculations and hence the cpu
speed isn't really relevant.  It is possible in some cases on high end
machines that using software raid will run faster than hardware raid
since the main cpu is many times faster than the dedicated cpu on some
hardware of the cheaper raid cards.

How many ide ports do you have or are you planning to use scsi?

Lennart Sorensen

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