ADSM-L

Re: AW: Incremental Forever

2000-05-02 16:46:26
Subject: Re: AW: Incremental Forever
From: Diego García <drgarcia AT JAVERIANA.EDU DOT CO>
Date: Tue, 2 May 2000 15:46:26 -0500
I´m agree with you, like a sysadmin newbie i need to make many test from 
bacukps,
with a scheme for incrementals the restore time is faster than a full backup
restore time, also if you take a time for make some scripts for use incremental
backups the execution improves.

Like a rookie i must say that your answer is very accurate because i know how 
many
time restore is needed for repares errors in a system, (many of them my
responsability)

Suggestions like yours make administration a pleasure, because i know the rigth
way to do administration routines

Thanks again

Diego García
System Manager
PUJ

"Allen S. Rout" wrote:

> => On Tue, 2 May 2000 07:35:43 +0200, sal Salak Juraj <sal AT KEBA.CO DOT AT> 
> said:
>
> > Allen,
>
> >> There is simply no technical reason to prefer a full/incremental scheme ...
>
> > There is one reason for not to go with incremental backup: the restore
> > speed.  Due to its very nature, the restore speed will be slower comparing
> > to restore from full backups. (when both use same tape HW) Depending on your
> > requirements an environmenmt this limitation does not necessarilly have to,
> > but do can apply.
>
> > best regards
>
> I'm sorry, but I must respectfully disagree with you.  In fact, a
> well-managed incrementals-forever scheme in a system like ADSM can be faster
> than a full/incremental scheme.  Consider:
>
> On any day except the day the full was taken, you must mount a minimum of two
> tapes to complete a restore.
>
> A TSM stgpool with colocation active (and adequate media levels) will only
> need a single mount, unless there is more than one tape's worth of data.
>
> There are of course variables in either scheme:
>
> If you're using "true incrementals", i.e. only backing up files changed since
> the last _backup_ instead of since the last _full_, you can require a whole
> weeks' tapes.
>
> You could have your data on a mostly-reclaimable tape, in which case you might
> need a second mount.
>
> etc. etc. etc.
>
> But in any case, a well-implemented storage managment system will be better
> than the average case for a full/incremental scheme, and will be much better
> than the worst case.
>
> - Allen S. Rout
> - NERDC TSM admin
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