Gordon Henderson wrote:
On Wed, 21 Dec 2005, Sebastian Kuzminsky wrote:
But how does the performance for read and write compare?
Good question! I'll post some performance numbers of the RAID-6
configuration when I have it up and running.
Post your hardware config too if you don't mind. I have one server with 8
drives and for swap (Which it never does!) I created 2 x 4 disk RAID 6
arrays (same partition on all disks) and gave them to the kernel with
equal priority
Filename Type Size Used Priority
/dev/md10 partition 1991800 0 1
/dev/md11 partition 1991800 0 1
md10 : active raid6 sdd2[3] sdc2[2] sdb2[1] sda2[0]
1991808 blocks level 6, 64k chunk, algorithm 2 [4/4] [UUUU]
md11 : active raid6 sdh2[3] sdg2[2] sdf2[1] sde2[0]
1991808 blocks level 6, 64k chunk, algorithm 2 [4/4] [UUUU]
/dev/md10:
Timing buffered disk reads: 64 MB in 0.66 seconds = 97.28 MB/sec
/dev/md11:
Timing buffered disk reads: 64 MB in 0.95 seconds = 67.59 MB/sec
md10 is an on-board 4-port SII SATA controller, md11 is 2 x 2-port SII
PCI cards. (Server is currently moderately loaded, so results are a bit
lower than usual
Cue the must/must not swap on RAID arguments ;-)
I wouldn't swap on RAID-6... performance is importand, swap is tiny
compared to disk size. I would go to 2GB partitions and four-way RAID-1,
since fast swap in seems to make for better "feel" and write is cached
somewhat.
--
bill davidsen <davidsen@xxxxxxx>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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