Cron usage


 
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Operating Systems HP-UX Cron usage
# 1  
Old 06-04-2009
Cron usage

Hi All,

I have one doubt,
Using one single cron file how many jobs we can shedule within a single user box

like

crontab -e XXX


* * * * * ---.sh
* * * * * ---.sh
* * * * * ---.sh
--
--
--


Regards,
Raghu.
# 2  
Old 06-04-2009
I am not aware of any limit...
we have a box with about 70 cron's

how many do you need??
# 3  
Old 06-06-2009
Maybe the OP means 'is there a limit to the size of a cron file?'

Not really. However maintining it is going to be difficult. You should use crontab -e on your crontab, so if you have thousands of entries it may become cumbersome to edit.
The other issue is one of flooding the system with jobs, which can affect performance.
# 4  
Old 06-09-2009
Jim pointed out what is the main concern of having plenty jobs scheduled and tansactionnal users at the same time: users working in interractive mode or submiting their jobs can flood the system at some periods when heavy scheduled batches are running...
I used to take care of a system with 3 crontabs running (root for backups policy, oracle for stop/export/start DB) and oper (operational production)
oper had around 200 plannified jobs with some having to be run and finish at given date and time (monthly paiment etc...).
If you add the comments in the file , you realise its about 500 lines long...
Although I was not in charge of the production, I was the one blammed when performance issue occured, which ment having the desagrable task of findinf culprits and killing them so production can continue...

And Jim's comment is to be seriously taken in account:
With already approx 200 lines - you can guess the hard work sorting the different lines that look the same but not quite to match with rules such as "on the second monday of the month" and "every 10 of each month" etc...

I once had the bad surprise of a user sending printing request on a friday afernoon and not seeing his printout strated again and again... then gave up and left for the weekend.
It just happened on the weekend where more than 60 heavy jobs were to run.
I was called out of bed VERY early morning sunday because of a non responsive machine...
At that point all I could do at the console was a reboot ( or was it "turn off the power"?)...
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