Veritas-bu

[Veritas-bu] NBU 3.4 incremental backup file choice

2001-02-04 23:54:21
Subject: [Veritas-bu] NBU 3.4 incremental backup file choice
From: fx [François-Xavier Peretmere] fx AT Veritas DOT com
Date: Mon, 5 Feb 2001 05:54:21 +0100
> From: Chad Haywood [mailto:chad.haywood AT storability DOT com]
> Sent: Friday 02 February, 2001 16:44

> I am looking for the mechanism by which NBU determines which
> files need to be included in an incremental backup, either differential
> or cummulative.  I assume there may be a different mechanism for UNIX
> clients (Solaris/Linux in particular) versus the NT/W2K clients.
>  Information both/either would be appreciated.

 the main difference between Unix and WinXX platform is the use by
the Microsoft OSes of the Archive bit.

 archive bit is set by the OS as soon a file is modified. so in theory,
a file with the A bit is a file that has been modified. those files
can be seen in the explorer (file details) or with the cmdmline
attrib command.

 problem is anybody can modify this bit, to set it or to clear
it - as long as ACLs permits it, of course. if you have a badly
written app that set it to every file it accesses, then your INCR
are going to be FULL. on the other hand, if an app (WinZip fe.)
clear it after zipping files, then files that should have been b/k won't
be.
 so using the archive bit is safe, as long as you don't have another
app messing with it.

 in the WinXX client options, you can configure it not to use this bit,
but only the time stamp instead.

 for Unix, it's more classical. the inode mtime is considered
to determine if a file has to bae backuped. this can be changed
with option USE_CTIME_ FOR_ INCREMENTALS.

 you'll find more details on this in the following section of
the NetBackup Administration Manual:

 Reference topics -> Incrementals backups overview.

 Amicalement,
              fx


# cat /usr/include/VRTS/std_disclaimer.h
 1) i speak for myself.
 2) sometimes i'm wrong
#

--
     fx AT Veritas DOT com       | Wind catches lily
François-Xavier Peretmere | scatt'ring petals to the wind.
 http://www.veritas.com/  | Segmentation fault.




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