[collectd] terrible perfomance of collectd

[Josef Liška]

Israel Garcia napsal(a):
>>> Can you help me?
>>>
>>>
>>>       
>> Hi,
>>     
> Hi Josef, thanks for your answer. :-)
>
>   
>> 1) try adjusting cache parameters:
>>
>> <Plugin rrdtool>
>>         DataDir "/var/lib/collectd/rrd"
>>         CacheTimeout 485
>>         CacheFlush 1800
>> </Plugin>
>>     
> OK, I'll try with this config
>
>   
>> The more sec you keep cache, the less io collectd generates. Tradeof is
>> in "lag" of graphs behind current time.
>>
>> 2) try adjusting filesystem params, if you are using ext3, try mount
>> options noatime,commit=600
>>     
> Now, "/var/lib/collectd/rrd" is in the same OS filesystem, I'll add a
> second hdd to my VM and put rrd files in this partition and set all
> this parameters in fstab.
>
>   
>> 3) change your raid configuration to raid0 or 10
>>     
> I can'nt this server only support raid 1 and 5. :-(
>
>   
>> 4) add more ram if your system is swaping
>>     
> The server is not using any swap.
>
>   
>> 5) adjust rrd files "time precision" if you do not need acuracy to
>> seconds, this will keep whole dataset smaller.
>>     
> Can you explain me this a little>?
>
> Thanks again Josef
> regards
> Israel.
>   

According to collectd man page, rrd files are usually created with step 
size set to interval.
If you change interval eg. to 30sec from 5sec, your rrd files are still 
with stepsize 5s,
since they were created with previously used config file.

Bigger interval means smaller rrd files, which could hopefully fit into 
filesystem caches.

If you want to try impact of changing this, you can easily move wholo 
your rrd collection to backup location, retart collectd and let it 
recreate rrd files with new interval.
        rrdtool dump filename.rrd >filename.xml
        edit filename.xml
        rrdtool restore --force-overwrite filename.xml filename.rrd


If you want to keep old data and change rrd files step size, it is a bit 
more difficult, AFAIK.
You have to dump rrd files using rrdtool dump to xml, then edit xml 
(with some script) and load edited xml back to rrd file using rrdtool 
restore

> StepSize Seconds
>
>     Force the stepsize of newly created RRD-files. Ideally (and per 
> default) this setting is unset and the stepsize is set to the interval 
> in which the data is collected. Do not use this option unless you 
> absolutely have to for some reason. Setting this option may cause 
> problems with the snmp plugin, the exec plugin or when the daemon is 
> set up to receive data from other hosts.

*
*
>> --
>>
>> S pozdravem
>> Josef Liška
>>
>> CHL | system care
>>
>> Telefon: +420.272048055
>> Fax: +420.272048064
>> Mobil: +420.776026526 denně 9:00 - 17:30
>> Jabber: jl at chl.cz
>> https://www.chl.cz/
>>
>>
>>     
>
>
>   


-- 

S pozdravem
Josef Liška

CHL | system care

Telefon: +420.272048055
Fax: +420.272048064
Mobil: +420.776026526 denně 9:00 - 17:30
Jabber: jl at chl.cz
https://www.chl.cz/

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