I'm using Linux and dump.

Roberto Samarone Araujo


> [This is a meta-answer, because I've heard people say "differential
>  backup", but I had no darn idea what it meant, and I figure there
>  might be others out there in the same boat!]
>
> On Wed, Jun 25, 2003 at 08:30:41AM -0300, Roberto Samarone Araujo (RSA)
wrote:
> >       It it possible to use amanda to do diferential backups ? Are there
any
> > specific configuration ?
>
> AFAICT, there are two meanings to "differential" when you're talking
> about backups.
>
> 1)  Databases.  For databases (e.g., Oracle, SQL) you are often backing
>     up a small number of very large files (and sometimes not files at
>     all, but raw partitions).  In this context, "differential" means
>     backing up only those blocks within a large file (or raw partition)
>     that have changed.
>
>     This is obviously the realm of a special-purpose backup program,
>     Amanda itself definitely doesn't know anything about it.
>
> 2)  Windows file systems.  Files on (all?) Windows file systems have an
>     "archive bit".  The intent is that this bit is set when a file is
>     modified.  The intent is that a full backup clears all the archive
>     bits.  In this context:
>
>     An "incremental" backup gets files that have changed since the full
>     or previous incremental, and re-clears the archive bits.
>
>     A "differential" backup gets files that have changed since the full,
>     and leaves the archive bits alone.
>
>     So this is sort of a round-about way of getting the same
>     differences in behavior you get my controlling level in dump.
>     Strictly speaking, Amanda doesn't know anything about this either.
>
> Since you're apparently a Windows guy, I'm guessing you mean "windows
> differential", not "database differential".  Is that correct?  And then
> the answer to your question depends on what type of file system you're
> backing up and what underlying backup engine (e.g., tar, dump,
> smbclient) you're using.
>
> -- 
> Jay Lessert                               jay_lessert AT accelerant DOT net
> Accelerant Networks Inc.                       (voice)1.503.439.3461
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