Forum: Cfengine Help Subject: Re: Random variable persistence problem -- crontab randomization Author: jgreer Link to topic: https://cfengine.com/forum/read.php?3,20077,20080#msg-20080
take care over this. Are you sure you want a "random time"? This is a commonly (ab)used phrase. What people usually want to do is the spread the times out evenly over an interval in a predictable way. A random time could have all hosts changing their behaviour all of the time, and might not spread out the numbers at all. I understand. You're right that a "random time" is not the goal, but distribution of the job more evenly (and predictably) across our hosts. I do not want the hosts changing their behavior all the time (i.e., one host runs this job at 1:13, 2:07, 3:41...) - see requirement #1 in my original post. What the splaytime does in Cfengine is to "hash" hosts over an interval of time so that as few hosts collide as possible and times are distributed evenly over the interval. That is not at all random, but it maps each host to a very specific time (whose value you don't particularly care about). I'm aware of splaytime and prefer it for scheduling because of its finer granularity and persistence. In this specific case, though, it's not a good solution, because of another business requirement: we schedule cf-execd to run the agent only at Min00 with a splaytime of 10 minutes, and we do not want agent runs to occur outside that window at the top of the hour. We want to distribute the run of this cron job across the hour to prevent overloading a server to which the cron job syncs files. If you want a predictable scheduling, I recommend running commands from inside Cfengine. Don't try to edit random numbers into the cron file. Cfengine commands are our preferred method of scheduling. While I'm trying to solve a scheduling problem, scheduling is not the heart of the problem I'm trying to solve - I'm interested to hear whether anyone has tried to solve the problem of generating "disposable," pseudo-random data client-side, and referring to that data in subsequent agent runs. It's not a problem I've run into before, and don't know that I will again in practice, but was interested whether the community had thoughts on the matter. Thanks, -Jessica _______________________________________________ Help-cfengine mailing list Help-cfengine@cfengine.org https://cfengine.org/mailman/listinfo/help-cfengine
