Lost File Recovery

Your HOME and PROJECTS directories on Anvil are protected against accidental file deletion through a series of snapshots taken every night just after midnight. Each snapshot provides the state of your files at the time the snapshot was taken. It does so by storing only the files which have changed between snapshots. A file that has not changed between snapshots is only stored once but will appear in every snapshot. This is an efficient method of providing snapshots because the snapshot system does not have to store multiple copies of every file.

These snapshots are kept for a limited time at various intervals. Please refer to Anvil File Systems to see the frequency of generating snapshots on different mount points. Anvil keeps nightly snapshots for 7 days, weekly snapshots for 3 weeks, and monthly snapshots for 2 months. This means you will find snapshots from the last 7 nights, the last 3 Sundays, and the last 2 first of the months. Files are available going back between two and three months, depending on how long ago the last first of the month was. Snapshots beyond this are not kept.

Only files which have been saved during an overnight snapshot are recoverable. If you lose a file the same day you created it, the file is not recoverable because the snapshot system has not had a chance to save the file.

Snapshots are not a substitute for regular backups. It is the responsibility of the researchers to back up any important data to long-term storage space. Anvil does protect against hardware failures or physical disasters through other means however these other means are also not substitutes for backups.

Anvil offers several ways for researchers to access snapshots of their files.

flost

If you know when you lost the file, the easiest way is to use the flost command.

To run the tool you will need to specify the location where the lost file was with the -w argument:

$ flost -w /home

This script will help you try to recover lost home or group directory contents.
NB: Scratch directories are not backed up and cannot be recovered.

Currently anchoring the search under:  /home
If your lost files were on a different filesystem, exit now with Ctrl-C and
rerun flost with a suitable '-w WHERE' argument (or see 'flost -h' for help).

Please enter the date that you lost your files:  MM/DD/YYYY

The closest recovery snapshot to your date of loss currently available is from
MM/DD/YYYY 12:00am.  First, you will need to SSH to a dedicated
service host zfs.anvil.rcac.purdue.edu, then change your directory
to the snapshot location:
    $ ssh zfs.anvil.rcac.purdue.edu
    $ cd /home/.zfs/snapshot/zfs-auto-snap_daily-YYYY-MM-DD-0000
    $ ls

Then copy files or directories from there back to where they belong:
    $ cp mylostfile /home
    $ cp -r mylostdirectory /home

Here is an example of /home directory. If you know more specifically where the lost file was you may provide the full path to that directory.

This tool will prompt you for the date on which you lost the file or would like to recover the file from. If the tool finds an appropriate snapshot it will provide instructions on how to search for and recover the file.

If you are not sure what date you lost the file you may try entering different dates into the flost to try to find the file or you may also manually browse the snapshots in /home/.zfs/snapshot folder for Home directory and /anvil/projects/.snapshots folder for Projects directory.