Hello,
Here are the results using 5 disks for RAID 5 – basically the same
results but with lower values.
Again, much slower than it could be.
*** dd TEST ***
time dd if=/dev/zero of=/dev/md0 bs=1M
2819620864 bytes transferred in 23,410720 seconds (120441442 bytes/sec)
iostat 5 output:
avg-cpu: %user %nice %sys %iowait %idle
0,10 0,00 55,40 36,20 8,30
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
hda 0,00 0,00 0,00 0 0
sda 0,00 0,00 0,00 0 0
sdb 345,09 1999,20 71501,40 9976 356792
sdc 348,10 2412,83 71434,07 12040 356456
sdd 356,31 2460,92 71748,30 12280 358024
sde 351,50 2456,11 71058,92 12256 354584
sdf 348,10 2008,82 70935,47 10024 353968
sdg 0,00 0,00 0,00 0 0
sdh 0,00 0,00 0,00 0 0
sdi 0,00 0,00 0,00 0 0
sdj 0,00 0,00 0,00 0 0
sdk 0,00 0,00 0,00 0 0
sdl 0,00 0,00 0,00 0 0
sdm 0,00 0,00 0,00 0 0
sdn 0,00 0,00 0,00 0 0
md0 35226,65 0,00 281813,23 0 1406248
disktest gives 99 MB/s but shows the same behaviour (unbalanced usage of
disks).
Regards,
Mirko
Ming Zhang schrieb:
i would like to suggest u to do a 4+1 raid5 configuration and see what
happen.
Ming
On Fri, 2005-08-26 at 09:51 +0200, Mirko Benz wrote:
Hello,
We have created a RAID 0 for the same environment:
Personalities : [raid0] [raid5]
md0 : active raid0 sdi[7] sdh[6] sdg[5] sdf[4] sde[3] sdd[2] sdc[1] sdb[0]
1250326528 blocks 64k chunks
*** dd TEST ***
time dd if=/dev/zero of=/dev/md0 bs=1M
14967373824 bytes transferred in 32,060497 seconds (466847843 bytes/sec)
iostat 5 output:
avg-cpu: %user %nice %sys %iowait %idle
0,00 0,00 89,60 9,50 0,90
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
hda 0,00 0,00 0,00 0 0
sda 0,00 0,00 0,00 0 0
sdb 455,31 0,00 116559,52 0 581632
sdc 455,51 0,00 116540,28 0 581536
sdd 450,10 0,00 116545,09 0 581560
sde 454,11 0,00 116559,52 0 581632
sdf 452,30 0,00 116559,52 0 581632
sdg 454,71 0,00 116553,11 0 581600
sdh 453,31 0,00 116533,87 0 581504
sdi 453,91 0,00 116556,31 0 581616
sdj 0,00 0,00 0,00 0 0
sdk 0,00 0,00 0,00 0 0
sdl 0,00 0,00 0,00 0 0
sdm 0,00 0,00 0,00 0 0
sdn 0,00 0,00 0,00 0 0
md0 116556,11 0,00 932448,90 0 4652920
Comments: 466 MB / 8 = 58,25 MB/s which is about the same as a dd to a
single disk (58,5 MB/s). So the controller + I/O subsystem is not the
bottleneck.
Regards,
Mirko
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