[DRBD-user] % of utilisation on my drbd device

Andreas Kurz andreas at hastexo.com
Thu Jan 19 14:17:11 CET 2012

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


sorry if that might get double-posted ... I used wrong sender address on
initial reply ...

------

Hello,

On 01/19/2012 07:56 AM, Matthieu Lejeune wrote:
> Hello,
> 
> I have a primary/secondary node with 2 ressources.
> When I watch the i/O performance i look some think like this :
> 
> When I watch the physical drive utilisation :
> 
> root at relax:~# iostat -x /dev/sda 1
> Linux 2.6.32-5-amd64 (relax)     01/19/2012     _x86_64_    (16 CPU)
> 
> avg-cpu:  %user   %nice %system %iowait  %steal   %idle
>            0.02    0.00    1.09    0.02    0.00   98.87
> 
> Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
> avgrq-sz avgqu-sz   await  svctm  %util
> sda             220.78   700.91  555.52  374.88 20794.66 21227.05   
> 45.16     1.54    1.66   0.42  38.87
> 
> avg-cpu:  %user   %nice %system %iowait  %steal   %idle
>            0.04    0.00    0.17    0.00    0.00   99.79
> 
> Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
> avgrq-sz avgqu-sz   await  svctm  %util
> sda             186.00    48.00  211.00  162.00 15392.00  2624.00   
> 48.30     0.03    0.09   0.06   2.40
> 
> avg-cpu:  %user   %nice %system %iowait  %steal   %idle
>            0.00    0.00    0.29    0.00    0.00   99.71
> 
> Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
> avgrq-sz avgqu-sz   await  svctm  %util
> sda             197.00     9.00  379.00  117.00 19472.00  1172.00   
> 41.62     0.15    0.31   0.19   9.60
> 
> When I watch the drbd device utilisation :
> 
> root at relax:~# iostat -x /dev/drbd0 1
> Linux 2.6.32-5-amd64 (relax)     01/19/2012     _x86_64_    (16 CPU)
> 
> avg-cpu:  %user   %nice %system %iowait  %steal   %idle
>            0.02    0.00    1.09    0.02    0.00   98.87
> 
> Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
> avgrq-sz avgqu-sz   await  svctm  %util
> drbd0             0.00     0.00  775.16 1016.47 20729.96 21174.70   
> 23.39     0.94    5.51   0.56  99.85
> 
> avg-cpu:  %user   %nice %system %iowait  %steal   %idle
>            0.00    0.00    0.56    0.00    0.00   99.44
> 
> Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
> avgrq-sz avgqu-sz   await  svctm  %util
> drbd0             0.00     0.00  426.00  104.00 15648.00  1262.00   
> 31.91     5.19    0.15   1.87  99.20
> 
> avg-cpu:  %user   %nice %system %iowait  %steal   %idle
>            0.00    0.00    0.56    0.00    0.00   99.44
> 
> Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
> avgrq-sz avgqu-sz   await  svctm  %util
> drbd0             0.00     0.00  404.00  148.00 15888.00  1872.00   
> 32.17     5.78    0.33   1.80  99.60
> 
> avg-cpu:  %user   %nice %system %iowait  %steal   %idle
>            0.00    0.00    0.31    0.00    0.00   99.69
> 
> Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
> avgrq-sz avgqu-sz   await  svctm  %util
> drbd0             0.00     0.00  398.00  117.00 15632.00  1736.00   
> 33.72     5.28    0.10   1.94 100.00
> 
> avg-cpu:  %user   %nice %system %iowait  %steal   %idle
>            0.00    0.00    0.24    0.00    0.00   99.76
> 
> Device:         rrqm/s   wrqm/s     r/s     w/s   rsec/s   wsec/s
> avgrq-sz avgqu-sz   await  svctm  %util
> drbd0             0.00     0.00  406.00  106.00 15376.00  1382.00   
> 32.73     5.07    0.17   1.92  98.40
> 
> I don't understand why my drbd device is at 100 %util.
> 
> This is my ressource configuration : There are a raid 0 hardware with 12
> sas 15k drives.

So think you should get higher write?? performance from your setup ...
what are your current benchmarking results?

Looking at your config I suggest you read the performance tuning chapter
in the DRBD user guide ... assuming you have a raid controller with non
volatile cache and 10GBit interconnect you should really get quite near
to native speed with DRBD ....

Regards,
Andreas

-- 
Need help with DRBD?
http://www.hastexo.com/now

>
> resource data {
>   protocol C;
>
>   startup {
>     wfc-timeout 0;
>   }
>
>   disk {
>     on-io-error detach;
>   }
>
>   syncer {
>     rate 20M;
>     verify-alg md5;
>   }
>
>   on surtax {
>     device    /dev/drbd0;
>     disk      /dev/sda;
>     address   10.1.42.11:7788;
>     meta-disk internal;
>   }
>
>   on relax {
>     device    /dev/drbd0;
>     disk      /dev/sda;
>     address   10.1.42.12:7788;
>     meta-disk internal;
>   }
> }
>
> What's wrong on my configuration ?
>
> Thank's
>
> Matthieu
>
> _______________________________________________
> drbd-user mailing list
> drbd-user at lists.linbit.com
> http://lists.linbit.com/mailman/listinfo/drbd-user




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