The fileservers periodically take 'snapshots' of their entire filesystems, and users can recover files from these snapshots without any assistance from the Lab staff. This is not a general undelete facility. The fileservers take snapshots on a fixed scheduled, and files that aren't captured in a snapshot cannot be recovered this way. Hourly' snapshots are taken at 4am, 8am, noon, 4pm, and 8pm, nightly snapshots at midnight, and weekly snapshots at midnight Sunday. Note that the file snapshot times are approximate and may vary slightly and that 'hourly' does not mean every hour on the hour.
Recent snapshots stay on disk until they are overwritten by newer snapshots.
How long that is depends on the filer. Salado keeps 3 nightly snapshots and 10 'hourly' snapshots. The fileservers automatically create a .snapshot subdirectory for every directory in their filesystem. That subdirectory contains the files captured by the snapshots. You can see that hourly.0 is the most recent snapshot, while nightly.4 is the oldest snapshot.