Re: Software vs Hardware RAID 10?

[Goswin von Brederlow <brederlo@informatik.uni-tuebingen.de>]

Goswin von Brederlow <brederlo@informatik.uni-tuebingen.de> writes:

> Neil Gunton <neil@nilspace.com> writes:
>
>> I'm curious as to whether anyone has experience of software RAID in
>> Linux giving better overall performance on RAID10 than a RAID card
>> such as the Adaptec 2015S.
>
> I've tested a few raid setups in linux and the results are different
> from what you might expect. Changing hardware can impact your results
> a lot. So software raid can surprise you just as well as hardware
> raid.
>
> The ultimate answere is therefore: TEST YOURSELF.
>
>
> Anyway, some things I noticed:

and some I forgot:

raid6:
  A raid10 with 4 disks allows a maximum of 2 disks to fail. But only
  if the right disks fail and we all know murphy will kill the wrong
  one. So in praxis raid10 will only protect you against one disk
  failing.

  On the other hand raid6 will make 2 disk failures survivable, any
  two disks. If you can afford the cpu overhead for software raid6 I
  would allways prefer raid6 over a raid10 with 4 disks. With 6 disks
  too where raid6 also has more space and might be faster (at the cost
  of cpu usage).

MfG
        Goswin