Looking for a Good FreeBSD and General Unix Backup System

[Rich Kulawiec]

On Wed, Jan 28, 2009 at 05:11:22PM -0800, Doug Hardie wrote:
> Most certainly.  Use the restore function.  Interactive mode is easiest 
> for a small number of files.

Doug's correct.  The interactive mode of restore, with its
shell-like interface, is probably easiest if you're just looking for
two files or one directory or similar.  The non-interactive mode,
which has a syntax similar to tar's, is probably easiest if you're
going to restore many files/directories, or if you're going to
restore an entire filesystem.

Two notes to tuck away for future use:

First, when you use interactive mode, you use shell-like commands
(e.g., "cd", "ls") to navigate the directory hierarchy and pick out
what you want to restore.  You add each one to a list (that restore
keeps track of for you) and then, when you've selected them all,
you tell restore to extract them.  This is point where restore will
tell you that you haven't read any tapes yet, and ask you what tape
to read.  Tell it "1".  There's a long explanation behind this that
has to do with the days when 1600 BPI 9-track tapes were backup media,
and dumps often spanned multiple tapes, and so on.

Second, restore runs in user mode, so when it restores a file
(or all the files in an entire filesystem) it creates them through
the same mechanism any other user-mode program would.  That means,
from Unix's point of view, they're new files: new inode number,
and all that.  So if you're doing a major restore -- say, an entire
filesystem -- then you probably want to follow that up with a level 0
dump if you plan to do partial dumps.  Otherwise, those partial dumps
aren't going to have what you probably want them to have.  Arguably
this is inconvenient but (a) it's a rare circumstance (b) it's not
THAT inconvenient and (c) there's no good way around it without
sacrificing a lot of the power of dump.

Okay, three notes: it's often advisable to create a scratch directory
and restore into that, just in case you fumble-finger something.
Given that you're restoring, which means something has gone wrong,
possibly a big something, you may be stressed and hurried, and
thinking that this would be the worst possible time for something
ELSE to go wrong.  A scratch directory insulates you from most
of that.  (No, of course this is entirely based on other peoples'
experiences, it would never relate to my own...why do you ask?)

---Rsk