* and then Jon LaBadie declared....
> > > how much data do you have to backup?
> >
> > The entire contents of /dev/hda3 and /dev/hdb1 (see above) I just want a
> > complete restorable backup done of the entire system.
>
> Not a complete answer; data and disk capacity are not the same thing.
> I can see hdb1 is 187GB and you currently are using 10% of it for data.
> What do you anticipate for tomorrow and next year?
ahhh.. i see what you mean ;)
> BTW it is quite unusual to have your entire system (minus /opt)
> on a single humongous root file system. More often it will be
> subdivided into logical boundries, eg. /tmp with short-term, not
> to be retained across boot, /var with logs and admin stuff,
> /home with user data, /usr/local with stuff you add, /export
> with shared data, ...
It's just a home linux box. The gentoo docs that I followd to install
seemed to think that was ok for a home system... Quite frankly though,
i would like a better partition system but although gentoo rocks once
you've got it going, it's a bitch to install hehe!
> > > how frequently will you backup?
> >
> > Nightly, at 3am
> >
> > > how many full dumps vs. incrementals will you want to keep?
> >
> > Probably overwrite the backups each night. (incremental?)
> >
>
> Bzzzzt, bad answer :(
>
> Imagine a powerfailure happening at 3:20am. It corrupts your
> humongous root drive but your external drive seems ok.
> Unfortunately, you have now destroyed yesterday's backup as today's
> was underway and you don't have today's yet as it is not complete.
haha, a real 'gotcha!' - of course i now see your point..
> The common way to handle backups is periodically dump everything
> and then for a number of days backup only what has changed. This
> is refered to as a "dumpcycle", one full backups and a set of
> incrementals. It is also common to retain more than one dumpcycle,
> often several.
>
> The size of your data, not disks factors into how much space to
> leave for amanda's full dumps. Also, how rapidly your data
> changes affects how big your incrementals are.
So, one full dump (say once a week) and then incrementals to *add to the
full dump* nightly?
> > > mixing virtual tape, holding disk, and data being backed up
> > > on the same HD spindle is a sure performance hit.
> >
> > Yeah, but im planning on having it do its stuff while I sleep, i dont
> > run any public services from this machine, it's just my work/play box
> > ;-)
> >
>
> So it becomes a formula of how big is one full dump, how many extra
> incrementals in a dumpcycle, how big is an incremental, how many
> dumpcycles do you plan to retain, and how much will your data compress.
>
> You currently have about 25GB of data. If it might grow to 40GB,
> use that number. Guess on the change of data rate, ?10%?. How
> long between full dumps, ?1 week? equals six incrementals equals
> 6x40x0.1 or 24GB. Thus a dumpcycle would be about 64GB of backups.
> How many dumpcycles to retain ?1.5?, ?2?, ?3?. If the latter,
> then you will have on disk 3x64GB (192GB) of backup data. How
> much will it compress ?20%?, ?50%?, ?70%?. Fifty percent is
> a commonly used guess, so you would need about 100GB.
Yes, i get that. I've allocated 150g's to it just to be sure..
Thanks very much again for all the help, im sorry im late in replying,
it's been lovely weather this week and i've been having a few days
off... ;-)
--
Nick W
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