[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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