The Restore-o-Mounter: The File Motel Revisited
Joe Moran and Bob Lyon
Legato Systems, Incorporated
We present a scheme for referencing and accessing saved (( footnote 1:
We use the word "save" to denote the super set of "backup" and
"archive"; save is also easier to conjugate than backup.)) files in a
manner that is transparent to UNIX" applications. The scheme requires
no kernel modifications. Instead, it uses a "mounted" process that
allows users to change directories to the past and browse their saved
files with their favorite utilities. The mounted process acts as a
protocol gateway between NFS and a commercially available network
backup product. Time travel is supported; users may change directories
to any moment in the past. Any saved version (not just the most recent
version) of any file can be viewed or recovered, even if the file has
since been deleted.
Using this transparent method of retrieving saved files by naming
their location in the past, a poor man's file migration scheme can be
implemented by substituting a symbolic link to a saved location for a
file. Once a file is referenced, the symbolic link can be replaced
with its original file. This migration scheme requires no kernel
modifications yet remains transparent to UNIX applications and users.
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