RAID and Adaptec AAA131
Monty Harder
lists at kc.rr.com
Mon Jul 23 03:33:23 CDT 2001
7/17/01 8:16:47 AM, "Eric Rossiter" <rossiter at discoverynet.com> wrote:
>Morning Lugites,
>
>Someone posted a message the other day about how they mirror one drive on
>another using a simple shell script. Seems I have inadvertently deleted it.
I used to do this at work on a Windows network, and it goes like this:
XCOPY /S /M \server1sharename*.* \server2sharename*.*
The first time, you leave the /M(odified) switch off, or run a command to set all files to
"dirty". The same
functionality can be accomplished in *nix by capturing the current date and time in a small file to
keep track of the
cutoff time of the last backup. I admit my shell scripting skills aren't as good as my DOS/Win
Jedi Batch Trick abilities,
but (having not tested this) I believe the equivalent is:
cp -u -R _source_ _destination_
This doesn't work =exactly= the same, because TTBOMK ext lacks the "archive" attribute. The -u
switch does a fair job of
emulating it, though: If the destination has the same or newer Last Modified time, the file is not
copied. This approach
has the advantage over the XCOPY variant that the exact same shell command both creates and updates
the mirror, including
rebuilding any files you've deleted from the mirror. In fact, you can issue this command both
directions to make sure that
files deleted from either system are restored. (Which brings up the question of how you =delete=
files from the mirror that
have left the primary, and you're sure you want them gone - I'd be careful about spool and log
directories, frex.)
OTOH, you can use the /M approach with different destination paths per day of week, etc. to build
up a history of
versions of files, just as you get from tape backups. If you really want that kind of flexibility,
though, it would
probably be easiest to use tar instead.
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