[CentOS] Question about a hard drive error

Benjamin Franz jfranz at freerun.com
Tue Nov 16 13:41:11 EST 2010


On 11/16/2010 09:25 AM, John R Pierce wrote:
>
> These days of cheap drives, I use raid10 almost exclusively.  and if its
> at all mission critical, I like to have 1-2 hotspares.   if I was
> deploying a new server, and its workload was at all database-centric,
> I'd want to use use 2.5" SAS rather than 3.5" SATA
>
> With RAID10, the rebuild time is how long it takes to copy the one
> drive.   if you have 6 drives in a raid10 and one fails, leaving 5, and
> another fails, there's only a 1 in 5 chance of that other failure being
> the mirror of the dead drive.       If you have a  hot spare, that
> rebuild starts immediately, reducing the window for that dreaded double
> failure to a minimum.
>

Oh, I agree - and when price is no object, or if write performance is 
the bottleneck, or if you need huge numbers of drives, I love RAID10. 
You can take it to crazy levels of redundancy + performance by going to 
RAID0 layered over multiple three-way RAID1 arrays. Why have multiple 
hotspares when you can go for N>2-RAID1 + 0 instead and get a hefty 
performance boost on reads for almost free at even higher reliability?

-- 
Benjamin Franz



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