Re: Performance question

[Bill Davidsen <davidsen@tmr.com>]

Piergiorgio Sartor wrote:
> Hi all,
>
> I'll have to setup some machines with two HDs (each)
> in order to get some redundancy.
>
> Reading the MD features I noticed there are several
> possibilities to create a mirror.
> I was wondering which one offer the best perfomances
> and/or what are the compromises to accept between
> the different solutions.
>
> One possibility is a classic RAID-1 mirror.
> Another is a RAID-10 far.
> There would also be the RAID-10 near, but I guess
> this is equivalent to RAID-1.
>
> Any suggestion on which method offers higher "speed"?
> Or there are other possibilities with 2 HDs (keeping
> the redundancy, of course)?
>   

Mirrored array will offer slower write speed no matter how you do it, 
usually about the speed of a single drive. With raid10 far you should 
get about N times faster read than a single drive, where N is drives in 
the array. Clearly using three or more drives will help a LOT in typical 
performance.

-- 
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