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-   -   What % of cpu does software raid take nowadays? (http://www.linuxquestions.org/questions/showthread.php?t=4175435412)

Ulysses_ 11-03-2012 01:29 AM

What % of cpu does software raid take nowadays?
 
For video we used to go for gpu hardware acceleration but nowadays cpu's are so fast that they can play video with software rendering, eg in virtu machines where no gpu hardware acceleration is available.

Does the same apply to software raid with the cpu's of today?

What is a typical cpu % used during a disk intensive operation with software raid on ssd's?

jefro 11-04-2012 10:06 AM

I haven't seen any tests on it for years. A long time ago it was really resource intensive and didn't increase speed (much slower) but did provide mirror well enough.

I suspect that any tests against a real hardware raid card will be poor. Search the web for any current tests on systems. The issue would be also what is the usual load of the system. A simple test bed only running a disk file test would not be the same as a real system under load trying that same test.

TobiSGD 11-04-2012 11:00 AM

I have run RAID 0,1 and 5, all in the software (so no data about hardware RAID here) on a Phenom II X6 1055T and performance was good, with no noticeable impact on the CPU.

Ulysses_ 11-04-2012 02:36 PM

Does it perhaps overload the memory access but not the cpu, so that any process with a lot of memory access becomes significantly slower?

TobiSGD 11-04-2012 03:26 PM

I can't say. I have only used it on machines with 8GB RAM or more and haven't monitored the RAM usage of the kernel, but as far as I can say there where no slowdowns when running applications with high RAM usage.

jefro 11-04-2012 03:40 PM

It would be nice to see some current tests and as you point out, on an ssd. The filesystem and size of data is always part of the question.

While searching for some current data, one post joked. No one ever got fired for using a hardware raid. It still has some enterprise level uses. A home user may find software raid is fast.

Odd options might be like a raid-z.

I'd use software raid over a faux of fake raid.

If you have the ssd's then try a few tests and let us know how you like it.


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