Re: Disk or I/O latency?

[Martin Pala]

Hello,

yes, for native disk I/O charts, there will be Monit-side (agent) 
implementation needed (to collect data) and M/Monit side chart added. We'll add 
this most probably in the next version, which is currently in progress (no ETA 
available yet).

Best regards,
Martin

> On 03 Jun 2016, at 19:02, Pierre-Philipp Braun <address@hidden> wrote:
> 
> Hello Martin,
> 
> yes I am more interested in I/O charts than alerts.  So my script is 
> currently useless and I need to wait until the custom charts feature _or_ 
> native i/o monitoring is available.  By next release do you mean 5.19 or 
> _major_ release ?
> 
> Although I am a sysadmin, I work with/for skilled programmers and I can have 
> them take a look at the code so they can help.  Can you point some places in 
> the code that would need to be enhanced to get the i/o charts?  Both the 
> agent and the m/monit server would need some tweaks, right?
> 
> Thanks
> 
> On 26/05/2016 15:40, Martin Pala wrote:
>> You can use the "check program" to integrate that script to Monit. The 
>> script should return error in the case that the I/O limit is exceeded: 
>> https://mmonit.com/monit/documentation/monit.html#PROGRAM-STATUS-TESTING
>> 
>> The next M/Monit release will support custom charts, so it'll be possible to 
>> render charts for I/O. We also plan to add native I/O monitoring to Monit 
>> and related charts to M/Monit, so it'll be easier to use.
>> 
>> Best regards,
>> Martin
>> 
>> 
>>> On 26 May 2016, at 14:31, Pierre-Philipp Braun <address@hidden> wrote:
>>> 
>>> Many thanks Viktor for your input.  I also need IO performance monitoring 
>>> (not esp. lacenty like Bryna, graphs reporting usage would yet be nice) so 
>>> I wrote a little script based on your/Munin's method,
>>> 
>>> #!/bin/bash
>>> 
>>> [[ ! -d /sys/block/ ]] && echo /sys/block/ does not exist, exiting && exit 1
>>> #[[ ! -d /var/cache/monit/ ]] && echo /var/cache/monit/ does not exist, 
>>> exiting && exit 1
>>> mkdir -p /var/cache/monit/
>>> 
>>> for disk in `ls -1 /sys/block/ | egrep -v '^fd|^dm-|^sr'`; do
>>>        readio=`cat /sys/block/$disk/stat | awk '{print $1}'`
>>>        writeio=`cat /sys/block/$disk/stat | awk '{print $5}'`
>>>        echo "$readio,$writeio" >> /var/cache/monit/$disk.stat
>>>        unset readio writeio
>>> done
>>> 
>>> it produces,
>>> 
>>> # pwd
>>> /var/cache/monit
>>> # ll
>>> total 16K
>>> drwxr-xr-x   2 root root   51 May 26 14:21 .
>>> drwxr-xr-x. 15 root root 4.0K May 26 14:20 ..
>>> -rw-r--r--   1 root root   26 May 26 14:21 sda.stat
>>> -rw-r--r--   1 root root   18 May 26 14:21 sdb.stat
>>> -rw-r--r--   1 root root   12 May 26 14:21 sdc.stat
>>> # cat *
>>> 17579,219210
>>> 2292,480
>>> 939,3
>>> 
>>> How to integrate this into Monit?  Is CSV a good choice as a format?
>>> 
>>> 
>>> 
>>> On 18/05/2016 23:05, SZÉPE Viktor wrote:
>>>> Munin does it by comparing `cat /sys/block/*/stat` e.g `cat
>>>> /sys/block/sda/stat` with the previous reading. This file contains 11
>>>> values:
>>>> https://github.com/munin-monitoring/munin/blob/devel/plugins/node.d.linux/diskstats#L440-L444
>>>> 
>>>> 
>>>> So previous rd_ios minus current rd_ios gives you and average IO/period.
>>>> You may "remember" these by storing them in a file, for example in
>>>> /var/cache/monit/sda.stat
>>>> 
>>>> 
>>>> 
>>>> Idézem/Quoting Graham Smith <address@hidden>:
>>>> 
>>>>> I don't think there is anything built in for that. You may not need a
>>>>> script per se, an application may have an exit status you could use to
>>>>> denote a fail or success of performance quality. Possibly iostat or
>>>>> iometer
>>>>> perhaps.
>>>>> If it's not a simple numeric output, a wrapper script might not need
>>>>> to be
>>>>> long and that could output a simple exit status to denote a success
>>>>> quality
>>>>> which monit can handle easier.
>>>>> 
>>>>> I always think it's best to keep complexity out of monit and if you
>>>>> need to
>>>>> do something fancy a script for anything odd is ultimately more
>>>>> modular as
>>>>> you may find other uses for it.
>>>>> 
>>>>> Graham
>>>>> On 18 May 2016 19:04, "Bryan Harris" <address@hidden> wrote:
>>>>> 
>>>>>> Hello all,
>>>>>> 
>>>>>> Does Monit have a way to measure i/o latency and alert if say a 4k write
>>>>>> takes longer than some number of ms?  I searched the mailing list and
>>>>>> manual and do not see anything.  Otherwise I can always monitor a custom
>>>>>> script for this purpose.
>>>>>> 
>>>>>> Thanks in advance.
>>>>>> 
>>>>>> V/r,
>>>>>> Bryan
>>>>>> 
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>>>>>> 
>>>> 
>>>> 
>>>> 
>>>> SZÉPE Viktor
>>> 
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