CAEN's NAS server offers access to extensive backups of each user's NAS space through a system of snapshots, or checkpoints. A checkpoint is a point-in-time copy of all the files and directories in the file system. A series of hourly, nightly, and weekly checkpoints are performed regularly. This can be very useful for self-service file recovery of recently changed or deleted files. The checkpoint mechanism is independent of and in addition to CAEN’s normal tape backup mechanism.

To access the backup copy of any directory in your storage space, you simply need to add .ckpt (short for checkpoint) to the path of the directory. For example, if you wanted to access the backup checkpoint for your Public directory, located at:

• \\storage.engin.umich.edu\home\Public\

You would simply enter the following in the address bar of your window:

• \\storage.engin.umich.edu\home\Public\.ckpt\

You will then be presented with a window containing a list of folders, each one named for the date and time the snapshot was taken (i.e. year_month_day_hour.minute.second_EDT):

Choose the date/time for which you need a backup copy, and double-click the folder. Note: These folders are read-only and the files in them cannot be modified. You also cannot save files to these folders. If you wish to modify any files in your backup directories, you first will need to copy the files from the .ckpt directory to modify them.