Bart Trojanowski wrote:
* Milan Budimirovic <milan [ dot ] budimirovic [ at ] sympatico [ dot ] ca> [060619 20:15]:
Since you asked:
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root@oconnor:/etc# hdparm -tT /dev/sda1
/dev/sda1:
Timing cached reads: 4188 MB in 2.00 seconds = 2094.00 MB/sec
Timing buffered disk reads: 218 MB in 3.01 seconds = 72.43 MB/sec
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The numbers are almost identical to software raid
(http://www.jukie.net/~bart/blog/raid10-performance).
But I bet you get 0 cpu overhead :)
Well, not quite identical. There is about a 20% difference in
buffer-cache reads and a 10%-20% difference in disk reads.
Here's the data from one of my SCSI RAID5 setups (5x10k 36G SCSI, LSI
MegaRAID Dual-Channel controller):
/dev/sda2:
Timing buffer-cache reads: 128 MB in 0.18 seconds =711.11 MB/sec
Timing buffered disk reads: 64 MB in 0.61 seconds =104.92 MB/sec
This server has to keyword-index 600,000 flat files every day. I suspect
that the SCSI RAID would be *much* faster but you never know.