Re: Bad iostat numbers - Mailing list pgsql-performance

From David Boreham
Subject Re: Bad iostat numbers
Date
Msg-id 456F9262.4080207@boreham.org
Whole thread Raw
In response to Bad iostat numbers  ("Carlos H. Reimer" <carlos.reimer@opendb.com.br>)
Responses Re: Bad iostat numbers
RES: Bad iostat numbers
List pgsql-performance
Carlos H. Reimer wrote:

>
>
> avg-cpu:  %user   %nice %system %iowait   %idle
>
>           50.40    0.00    0.50    1.10   48.00
>
>
>
> Device:    rrqm/s wrqm/s   r/s   w/s  rsec/s  wsec/s    rkB/s    wkB/s
> avgrq-sz avgqu-sz   await  svctm  %util
>
> sda          0.00   7.80  0.40  6.40   41.60  113.60    20.80
> 56.80    22.82 570697.50   10.59 147.06 100.00
>
> sdb          0.20   7.80  0.60  6.40   40.00  113.60    20.00
> 56.80    21.94 570697.50    9.83 142.86 100.00
>
> md1          0.00   0.00  1.20 13.40   81.60  107.20    40.80
> 53.60    12.93     0.00    0.00   0.00   0.00
>
> md0          0.00   0.00  0.00  0.00    0.00    0.00     0.00
> 0.00     0.00     0.00    0.00   0.00   0.00
>
>
>
> Are they not saturated?
>
>
>
> What kind of parameters should I pay attention when comparing SCSI
> controllers and disks? I would like to discover how much cache is
> present in the controller, how can I find this value from Linux?
>
>
These number look a bit strange. I am wondering if there is a hardware
problem on one of the drives
or on the controller. Check in syslog for messages about disk timeouts
etc. 100% util but 6 writes/s
is just wrong (unless the drive is a 1980's vintage floppy).



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