[Users] Reduce Load in VZs

[Kir Kolyshkin]

On 08/03/2011 11:11 AM, Tim Small wrote:
> On 03/08/11 07:55, me at free-minds.net wrote:
>> Hello,
>> We have on our Server about 17VZs installed and running. Most of them run
>> simmilar cron jobs, e.g. apticron and this causes very high load at night.
>>
>> Is there any best practise that we can use to reduce the load with these
>> jobs? I tought about running these cronjobs from outside with vzctl exec
>> (so make a cron at the host and just start the programms manually) and run
>> only 1 job at once.
>>
>> In general: Is there a best practise to run things in every VZ and not
>> produce high load?
>>
>>
> I patched the openvz scripts to randomise the start-time of these
> scripts across containers.  One of my clients had the same problem - it
> showed up quite clearly using the openvzcpu munin plugin which I wrote...
>
> I'll dig out the patch later.  Bug me if I haven't within 24 hours.
>
> Tim.
>
Interesting. vzctl does crontab randomization, by means of 
/etc/vz/dists/scripts/vps-postcreate.sh
script, so the question is why it is not working. I can see a few 
reasons why it's not working as it should:

(1) CT was created not by vzctl
(2) CT has been upgraded from the inside, so /etc/crontab was being modified
(3) CT has a distro installed which has crontab in some unusual location
(4) Some other bug?