Re: 4 disks: RAID-6 or RAID-10 ..

[Bill Davidsen <davidsen@tmr.com>]

Gordon Henderson wrote:

>On Fri, 17 Feb 2006, Francois Barre wrote:
>
>  
>
>>2006/2/17, Gordon Henderson <gordon@drogon.net>:
>>    
>>
>>>On Fri, 17 Feb 2006, berk walker wrote:
>>>
>>>      
>>>
>>>>RAID-6 *will* give you your required 2-drive redundancy.
>>>>        
>>>>
>>Anyway, if you wish to resize your setup to 5 drives one day or
>>another, I guess raid 6 would be preferable, because one day or
>>another, a patch will popup and make raid6 resizing possible. Or won't
>>it ?
>>    
>>
>
>Resizing isn't something I really care for. This particular box will be
>sent away to a data centre where it'll stay for 3 years until I replace
>it.
>
>(And if I really do need more disk space in the meantime, I'll just build
>another :)
>
>Still scratching my head, trying to work out if raid-10 can withstand
>(any) 2 disks of failure though, although after reading md(4) a few times
>now, I'm begining to think it can't (unless you are lucky!) So maybe I'll
>just stick with Raid-6 as I know that!
>

With only four drives you can just do the possible failure cases, there 
are only six... when any one drive fails you can only survive the 
failure of two of the three remaining drives, not what you wanted. How 
reliable do you NEED here is the real question.

It isn't too hard to make the drives more reliable than the case they're 
in, how many fans and power supplies can you survive losing?

-- 
bill davidsen <davidsen@tmr.com>
  CTO TMR Associates, Inc
  Doing interesting things with small computers since 1979