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We currently use the ".snapshot" feature of our Netapp fileserver to provide online backups, of the central fileservers, that are accessible via the hidden ".snapshot" directory.

Every directory has a "snapshot" subdirectory that is visible only if explicitly named. I.e. it won't show up in the output of an "ls", but will show up in the output of "ls .snapshot". Each snapshot directory contains directories with names like:

 • hourly.N - the Nth hourly backup
 • nightly.N - the Nth daily backup
 • weekly.N - the Nth weekly backup

where the 0th backup is the most recent. In these subdirectories you can expect to find backups of all of the contents of the directory that contains the ".snapshot" directory (Your homedir). E.g. the most recent backup for a file with a name like "cool/program.c" could be found in ".snapshot/hourly.0/cool/program.c".

Some attempts to use the .snapshot files will fail. For instance, a simple "cp" command to copy a .snapshot file to its non-.snapshot counterpart will often fail if the counterpart already exists. This is because the two files may share the same "unique identifier" or "inode" number, as the "-i" option of the "ls" command will reveal. There are various ways to work around this, the simplest being to "rm" the intended destination before attempting the "cp".

Page last modified on 9. Sep 2013, at 19:54