Device utilization with RAID-1

2 messages, 2 authors, 2011-08-16 · open the first message on its own page

Device utilization with RAID-1

From: Harald Nikolisin <hidden>
Date: 2011-08-16 00:39:47

Since a long time I'm unhappy with the performance of my RAID-1 system.
Investigation with atop and iostat unveils that the disk utilization is
always on a certain level although nothing happens on the system. In the
case of reading or writing files the utilization boosts always to 100%
for a long time. Very ugly examples are "Firefox starting" or "zypper
updates".
That is snapshot of the output of iostat:


Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
avgrq-sz avgqu-sz   await  svctm  %util
sda               0,00     0,00    0,00    7,33     0,00    43,33    
5,91     0,33   43,18  33,32  24,43
sdb               0,00     0,00    0,00    7,33     0,00    43,33    
5,91     0,35   45,59  39,73  29,13
md0               0,00     0,00    0,00    0,67     0,00     5,33    
8,00     0,00    0,00   0,00   0,00
md1               0,00     0,00    0,00    0,33     0,00     5,33   
16,00     0,00    0,00   0,00   0,00
md2               0,00     0,00    0,00    0,33     0,00     1,00    
3,00     0,00    0,00   0,00   0,00
md3               0,00     0,00    0,00    0,00     0,00     0,00    
0,00     0,00    0,00   0,00   0,00
md4               0,00     0,00    0,00    0,00     0,00     0,00    
0,00     0,00    0,00   0,00   0,00
md5               0,00     0,00    0,00    0,33     0,00     0,67    
2,00     0,00    0,00   0,00   0,00

I checked with mdadm if a resync happens or so, but this is not the
case. The state says "active" on all RAID devices - btw. what is the
difference to "clean" ?

thanks for any hints,
  harald

Re: Device utilization with RAID-1

From: Roberto Spadim <hidden>
Date: 2011-08-16 01:30:18

try raid10 with far layout

2011/8/15 Harald Nikolisin [off-list ref]:
Since a long time I'm unhappy with the performance of my RAID-1 system.
Investigation with atop and iostat unveils that the disk utilization is
always on a certain level although nothing happens on the system. In the
case of reading or writing files the utilization boosts always to 100%
for a long time. Very ugly examples are "Firefox starting" or "zypper
updates".
That is snapshot of the output of iostat:


Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
avgrq-sz avgqu-sz   await  svctm  %util
sda               0,00     0,00    0,00    7,33     0,00    43,33
5,91     0,33   43,18  33,32  24,43
sdb               0,00     0,00    0,00    7,33     0,00    43,33
5,91     0,35   45,59  39,73  29,13
md0               0,00     0,00    0,00    0,67     0,00     5,33
8,00     0,00    0,00   0,00   0,00
md1               0,00     0,00    0,00    0,33     0,00     5,33
16,00     0,00    0,00   0,00   0,00
md2               0,00     0,00    0,00    0,33     0,00     1,00
3,00     0,00    0,00   0,00   0,00
md3               0,00     0,00    0,00    0,00     0,00     0,00
0,00     0,00    0,00   0,00   0,00
md4               0,00     0,00    0,00    0,00     0,00     0,00
0,00     0,00    0,00   0,00   0,00
md5               0,00     0,00    0,00    0,33     0,00     0,67
2,00     0,00    0,00   0,00   0,00

I checked with mdadm if a resync happens or so, but this is not the
case. The state says "active" on all RAID devices - btw. what is the
difference to "clean" ?

thanks for any hints,
 harald
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-- 
Roberto Spadim
Spadim Technology / SPAEmpresarial
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