build out of a server advice

Merrill Oveson moveson at gmail.com
Mon Jun 25 10:10:54 MDT 2012


Anybody have a good recommendation for a RAID 5 Card?


On Mon, Jun 25, 2012 at 9:24 AM, Lloyd Brown <lloyd_brown at byu.edu> wrote:
> I would add that there are effective capacity differences between the
> different RAID levels.  For example, for N disks of K size:
>
> RAID5:
> total capacity = (N-1)*K
>
> RAID6:
> total capacity = (N-2)*K
>
> RAID10:
> total capacity = N*K/2
>
>
> Depending on your application, it's possible that, like you say "Disk is
> cheap", and that's enough to minimize the impact of capacity issue for
> the OP.  But I think it's wise to present all the details, and let him
> decide what's important for the application, budget, etc.
>
> I certainly like it when vendor reps, etc., do that for me.
>
> Lloyd Brown
> Systems Administrator
> Fulton Supercomputing Lab
> Brigham Young University
> http://marylou.byu.edu
>
> On 06/23/2012 10:27 AM, Nicholas Leippe wrote:
>> Raid6:
>> - can withstand any combination of double disk fault
>> - much worse healthy write performance than 1+0
>> - huge performance penalty in degraded and rebuild mode
>>
>> Raid1+0:
>> - can only withstand specific combinations of double disk fault (must
>> not be two pairs of the same mirror)
>> - minimal healthy write performance penalty
>> - performance hardly affected in degraded mode, rebuild mode is a
>> simple copy--no CPU calculations, just I/O
>
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