ADSM-L

Re: Easy ADSM?

2000-02-07 10:07:29
Subject: Re: Easy ADSM?
From: "Prather, Wanda" <Wanda.Prather AT JHUAPL DOT EDU>
Date: Mon, 7 Feb 2000 10:07:29 -0500
If you want a "snapshot" of filesystems equivalent to a full dump, you can
use the archive function.
Archive copies do not participate in versioning.


> -----Original Message-----
> From: Eric Lindbeck [SMTP:elindbec AT SCTCORP DOT COM]
> Sent: Sunday, February 06, 2000 1:56 PM
> To:   ADSM-L AT VM.MARIST DOT EDU
> Subject:      Re: Easy ADSM?
>
> Many thanks to everyone for their great suggestions!  Just one
> follow-up question:
>
> In his reply, Steve Branch described the following situation:
> "Say you have a  file that changes every day and you back it up every
> day and maintain 3 backup copies (just an example). Initially you have
> 3 good copies.  Then the user does something stupid to mess up the
> file. If the user calls you right then and asks you to restore  from
> backup you will be ok. Suppose the user doesn't call you thinking all
> will be better tomorrow. You backup the file that is no longer any
> good and one of your good backup copies ages off the system. The
> next day the user tries to fix the problem and still doesn't call.
> Since the file timestamp got updated again today the corrupt file is
> again backed up tonight and another of the good copies ages off. If
> the same thing happens the following day you will have nothing but
> corrupt copies of that file in ADSM."
>
> Even maintaining an ambitious number of versions (5?, 10?, 20?) is not
> enough to guarantee no data loss under the above circumstances.  It's
> always possible that the file was corrupted on the day before your
> oldest version was made.  As strange as it seems that users can work
> with corrupt data and not even know it, I've seen it happen a number
> of times.  In an extreme case, I had to go back over 2 months of
> historical backups to find the last good version of a file.
>
> In the 'old' way of doing things, I could keep 1 full backup per month
> in storage indefinitely.  Then, I could just go to our safe (or
> off-site provider) and pull the full backup from 2 months ago, merge
> the tape catalogs into the db, query the db for the file, and do the
> restore.  What is the *SM method for recovering data in this sort of
> situation?
>
> Thanks again!
> Eric Lindbeck
> SCT
<Prev in Thread] Current Thread [Next in Thread>