[H-GEN] Disk transfer speeds

Michael Anthon michael at anthon.net
Fri Aug 8 22:27:14 EDT 2003


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Kris Amy wrote:

>>The RAID5
>>setup should be reading 5 disks simultaneously, one of which is parity
>>data and "wasted".  I would have thought in this case that I should get
>>a much higher sustained rate.
>>
>>Maybe I'm missing the point somewhere ?
> 
> 
> Isn't raid 5 striping with parity split ? raid 4 is where the parity is on
> one disk.

Yes, but the point still remains the same, it should be reading from the 
5 disks simultaneously with 20% of the data being redundant.  I think in 
terms of reading speed the performance of 4 and 5 is the same.  If I 
understand things correctly the main (possibly only) advantage of 5 or 4 
is that is take less time to rebuild a failed disk (unless it's the 
parity disk in RAID4 that fails, in which case it would be faster).

Cheers
Michael


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