Re: raid10 on three discs - few questions.

[Bill Davidsen <davidsen@tmr.com>]

Jon Nelson wrote:
> On Feb 6, 2008 12:43 PM, Bill Davidsen <davidsen@tmr.com 
> <mailto:davidsen@tmr.com>> wrote:
>
>     Can you create a raid10 with one drive "missing" and add it later? I
>     know, I should try it when I get a machine free... but I'm being
>     lazy today.
>
>
> Yes you can. With 3 drives, however, performance will be awful (at 
> least with layout far, 2 copies).
>
Well, the question didn't include being fast. ;-)

But if he really wants to create the array now and be able to add to it 
later, it might still be useful, particularly if "later" is a small time 
like "when my other drive ships." Thanks for the input, I thought that 
was possible, but reading code isn't the same as testing.
> IMO raid10,f2 is a great balance of speed and redundancy.
> it''s faster than raid5 for reading, about the same for writing. it's 
> even potentially faster than raid0 for reading, actually.
> With 3 disks one should be able to get 3.0 times the speed of one 
> disk, or slightly more, and each stripe involves only *one* disk 
> instead of 2 as it does with raid5.

I have used raid10 swap on 3 or more drives fairly often. Other than the 
Fedora rescue CD not using the space until I start it manually, I find 
it really fast, and helpful for huge image work.

-- 
Bill Davidsen <davidsen@tmr.com>
  "Woe unto the statesman who makes war without a reason that will still
  be valid when the war is over..." Otto von Bismark