There are two logical scratch areas under AFS for DELPHI users, and there are also two others which are not under AFS, thus not as easily accessible (specially for writing). All of them are not backed-up. The ones on AFS are accessible through the environment variables $AFS_SCRATCH (or just $SCRATCH) and $SCRATCH_WEEK; as the name suggests, the latter is intended for files that would need a longer lifetime, even if this cannot be guaranteed.
Since the scratch areas tend to become full, a garbage collector is run to do some clean-up. A presentation (PS.gz,72KB) of the algorithm used was given at a Software Forum on 5 December 1996. The garbage collector daily produces a log file for each scratch area, with the list of files that have been deleted. The log files produced in the last week are available.
For big files needed just for a few days, a $CASTOR_SCRATCH area can be used. It is not under our garbage collector control, so the lifetime of files is not very well defined (it depends on the overall DELPHI Castor usage), but normally a few days is not a problem - sufficient, e.g. to transfer the file to your home lab. And of course if the file is needed for longer, then it should be stored directly in the user's $CASTOR_HOME directory. Please see our page with hints on the Castor usage.