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Re: RAID 6 mdadm

On 04/15/2013 02:44 PM, Dexter Filmore wrote:
> Am Wednesday 10 April 2013 23:54:28 schrieb Stan Hoeppner:
>> On 4/10/2013 12:32 PM, Dexter Filmore wrote:
>> It's not necessary to ask on linux-raid, and as you have not yet done
>> so, I'll clarify this now:
>> Both the md RAID1 and RAID10 personalities will read sectors in parallel
>> from both disks in a mirror pair in most circumstances.  This has been
>> the case for many years.  This is a read optimization only.  Writes
>> occur in parallel as well, obviously, but as it's the same data the net
>> data throughput isn't doubled, only the raw device throughput.  This
>> should be obvious to anyone.  I'm merely being complete in my description.
>> --
>> Stan
> Interesting. Only 1 and 10 or 5/6 as well?

My first thought is that raids 5 and 6 use parity data, not duplicate
copies, so no.  After more thought, perhaps there could be a small read
boost in certain situations where data is spread across several drives.
 That said, it would be nowhere near the performance of raids 0/1/10.

Anyone with more direct experience?

- PaulNM

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