Tweakers.net has completed a comparison of 9 serial ATA RAID 0/1/5/10
There is a specific section on MySQL performance in the section:
Just thought these articles would be of interest to some (it's interesting
to see the difference between single drive operations and multiple drive
operations - up to 12 drives, with the different RAID levels).
Here's my rough speed comparison based upon eyeballing the graphs. Some
controllers were better than others so this represents a rough average of
the entire set of controllers:
Single drive - 1.0
RAID 1 - 2 disks - 1.4
RAID5 - 3 disks - 1.7
RAID5 - 4 disks - 2.0
RAID10 - 4 disks - 2.0
RAID5 - 6 disks - 2.3
RAID5 - 8 disks - 2.4
RAID5 - 10 disks - 2.9
RAID5 - 12 disks - 3.1
The article also highlighted the difference between the reliable
write-through mode and the write-back mode. In write-through mode,
performance is degraded by approximately 50%. Clearly if you want
reliability, a controller with a battery backup is highly recommended.
On the issue of SCSI version SATA performance, it would appear that SCSI
still performas somewhat better (about 20% more transactions but the test
was comparing 15K RPM SCSI drives to 10K RPM SATA drives) but the reduced
cost of SATA drives allows you to add more drives to achieve the same
performance levels at lesser cost. With Serial ATA II drives around the
corner (with Native Command Queueing) then I think we'll find SATA will take
a much bigger lead in database performance.
Really nice work from tweakers.net - would have been interesting to see the
Linux performance too though.
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