Snapshots

The NetApp filesystem provides a convenient way to recover files which have been accidentally deleted or otherwise damaged, within a short time frame – a system referred to as “snapshots”. File recovery becomes a simple copy procedure on the current filesystem, avoiding the necessity of Systems Administration hands-on interaction.

Directories which provide the snapshot feature are easily recognized by the presence of a .snapshot directory within (named as ~snapshot on Windows machines.) Currently, snapshots are enabled on /home, /uusoc/res, and /uusoc/sys.

Snapshots currently span a four week period. Four weekly backup directories, six nightly and 23 hourly directories provide a level of granularity sufficient for most restoration needs.

Hourly backups are done at every hour except midnight. At midnight, the nightly snapshot is made. Weekly snapshots are taken each Sunday. The sub-directories created in the .snapshot directory are ordered chronologically, with a numbered suffix indicating the age, such as /uusoc/res/gdc/.snapshot/hourly.7

The larger the number in the sub-directory’s suffix, the older the snapshot. For example, a user’s /home/username/.snapshot/hourly.0 directory will contain the most recent snapshot of /home/username, while /home/username/.snapshot/hourly.7 would contain the snapshot of /home/username seven hourly snapshots previous.

If you have proper permissions to browse the original directory, you can ‘cd’ into the matching snapshot directories and freely browse them.

Restoring a File from a Snapshot

As mentioned before, restoring a file is simply a copy command. In the following example, we’ll assume that you are logged into one of the facility Unix systems.

To restore /home/username/tmp/myfile.txt from a snapshot four hourly cycles back, you would use:

cp -a /home/username/.snapshot/hourly.3/tmp/myfile.txt /home/username/tmp/myfile.txt

(Remember, chronological labels start with 0, not 1. Four cycles back would be marked “3”.)

On a Windows system, the same can be accomplished by opening a window for U:\~snapshot\hourly.3\tmp and dragging the file myfile.txt to a window for U:\tmp

Disk-to-Disk Backups

In addition to the local snapshots, a second filer keeps disk-to-disk copies of our primary filer.  Backups are currently done at least daily and as often as every hour depending on the load it puts on our file server; however, snapshots are only kept on a monthly basis on the backup filer.  You should use the snapshot instructions above if you wish to retrieve a file that is less than a month old.

Should you wish to retrieve a copy of a file that is more than a month old, you can access it via shell.cs.utah.edu:/uusoc/backups/{res,sys,home}/.snapshot/monthly.X.  Where ‘X’ is a digit starting at 0 and is incremented by one for each month. i.e. 0 is the current month, 1 is one month ago, etc.  These directories: home, res, and sys, are automount points so you’ll have to cd into them before they become visible.

Filesystems Served from the NetApp Servers

The following is a chart showing the served volumes and their respective mapping to Unix (NFS) and Windows (CIFS/SMB) systems.

NFS Export	Unix Mount Point
ithaca.cs.utah.edu:/vol/vol3/home	/home
(N/A See above.)	/home/{username}
ithaca.cs.utah.edu:/vol/vol1/sys	/uusoc/sys
ithaca.cs.utah.edu:/vol/vol2	/uusoc/res

All of the above mount points should already be set up on facility managed Unix systems.

Quotas

The quota system for the NetApp filesystem is covered in the Quota Guide. Please refer there for further information.