[CentOS] RAID 5 setup?

Mike McCarty Mike.McCarty at sbcglobal.net
Thu Mar 25 23:36:22 UTC 2010


Robert Heller wrote:
> At Thu, 25 Mar 2010 22:27:56 +0100 CentOS mailing list <centos at centos.org> wrote:
[...]

> 
>> The root of the problem lies in the fact that when a disk fails, you  
>> have to read-out the data from the other disks to re-build the RAID.
>> Reads from disks have a certain probability to contain an error.
>> The larger the disk and the larger the array, the more probable it is  
>> to encounter such an error while rebuilding the RAID (and if that  
>> happens, you're RAID is just a piece of scrap-metal)
> 
> Or as was done recently at the Wendell Free Library, your disks become
> raw materials for an after school art project... :-)

It depends on how redundant the array is. With enough
redundancy, one can rebuild even if more than one disc
fails. RAID is essentially indistinguishable from ECC.
If the number of errors (failed reads from discs) does
not exceed the correction ability of the code used
(usualy a Reed-Solomon BCH style code) then the reconstruction
can proceed.

Mike
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