Re: [HTCondor-users] Outage timekeeping?

[Todd L Miller <tlmiller@xxxxxxxxxxx>]

> However, I'm wondering if there is there an established way to create 
> persistent machine classads without involving state files.

	Have you looked at OFFLINE and ABSENT ads in the collector?

	Absent ads are written to disk and persist across restarts and 
reboots.  An ad becomes "absent", IIRC, when it would otherwise age out of 
the collector.

	(Ads age out of the collector every few minutes; I forget which 
knob controls the rate.  IIRC, if an ad isn't updated for three 
consecutive update intervals, the collector throws it away, figuring that 
Something Terrible has happened to either the daemon sendint it or the 
network in between.)

	The intended use of absent ads is to make it possible to check, 
via the collector, which machines "should" be in your pool as opposed to 
which ones actually are.  (Obviously, if your pool is glide-ins, this is 
mostly useless.)  There's a knob you can use to determine which ads you 
keep (e.g., you only want uptime numbers for startds you control).

	The absent ad will contain the ad's usual attributes, including 
the last update time, which will give you an approximation of how long the 
machine has been down at the time that you checked.  This won't be quite 
the same number as downtime of the machine, or the downtime of the startd, 
but since (generally speaking) a startd that's not in the collector can't 
do useful work, it may be a number you care about, and close enough to 
what you actually want.

	Absent ads also eventually age out, and are also removed when an 
update for the same ad arrives.

- ToddM