February, 2012

MMT WFS - Files and Directories

We typically run the wavefront sensor software on one of the MMT control room linux computers (either yggdrasil or hoseclamp).

The working source should be found in /mmt/shwfs. Typically /mmt is either a link to /home/mmt or is a network mount of hacksaw:/home/mmt.

The environment variable WFSROOT is used within the software to specify the location of the WFS software tree. This allows a test copy of the software to be run at a different location by a developer without disturbing the software in daily use at the telescope. It should be noted though that there are still instances of hard-wired paths including /mmt/shwfs in the software, which makes this scheme imperfect at the present time.

Data files

The directory /mmt/wfsdat captures all of the data files used by and generated by the WFS software for all time. Within this directory are daily subdirectories of the form yyyymmdd (such as 20120202). Note that these snapshot directories are generated the morning after the nights observing and so will be timestamped for the day following. In other words the 20120202 directory has the files for the night following 2-1-2012.

As you might guess, this snapshotting is handled by cron. In the directory /etc/cron.daily we have a link to /mmt/admin/zzHACKSAWdaily.cron which in turn runs zzHACKSAWdaily.root.cron which in turn runs /mmt/admin/wfsdat_rotate.sh. It is this last script that captures the data files by making a copy of /mmt/shwfs/datadir after which it cleans out this directory so it is ready for the next night.

Fedora now uses "anacron", which is controlled by /etc/anacrontab. We have this set up so that the daily cron run is started "sometime after 7AM", but in any event between 7AM and 4PM.

Other computers

As described elsewhere, there are dedicated computers that host the wavefront sensor camera software which are used to capture images.