hi ya
On Wed, 24 Apr 2002, DSC Siltec wrote:
> DSC Siltec wrote:
>
> Ross Boylan wrote:
>
> >
> > I'm trying to do a fairly comprehensive system backup to CD-R. The
> > amount I have to backup is much larger than the free space on the
> > system, which in turn is larger than a CD-R.
> >
thats when the fun starts .... to backup 100Gb or more...
and they dont wanna lose data... ( terabytes of data )
- to have some degree of certainty that data is not lost...
- you must be able to recreate a full backup....multiple ways...
- if you lose your "full backup"...
- you can recreate it with monthly backups spanning 180 days ??
- you can recreate it with weekly backups spanning 90 days ??
( any loss of a weeks of data is not that bad as long
( as the subsequent week picks up previous weeks data
- you can recreate it with daily backups spanning 14 days ??
( lost any one or few days of data.. and you wont care
( except yesterday data myst be intact.. which is why
( you're looking at the backups anyway
- daily backups shaould always start from the day before full backups was
done ....
if full backup went bad...
( bad network, disks full, bad tape... etc... you must be able
to recover yesterdays files or any day where full backup died
a typical 100GB disk can hold about 2 months of full backups...
( typical mix of user data ...
( but if the data is 100% jpegs and mpegs...
( than compression isnt gonna help any
- all that can be done with one backup script w/ "-mtime option"...
- instant ( -- use disk mirroring -- )
- hourly ( find /etc /home -mmin -24 ) ( 24 hrs )
- daily ( find /etc /home -mtime -7 ) ( 7 days )
- weekly ( find /etc /home -mtime -30 )
- monthly ( find /etc /home -mtime -180 )
- problem with mirroring...
- if you or your friendly ( [cr/h]acker ) erases foo on /dev/md0
... than its gone from all your other mirrors too...
- mirroring is good..when done right...
c ya
alvin
http://www.Linux-Backup.net
> Just a thought -- I have heard that CD-Rs have a 1-bit per 100kB error
> rate in 1 year. What that means is that in your typical 1-Meg program,
> backed up to CD-R, you're not going to be able to use it after about a
> year.
>
> So CD-R would *only* be useful for short term backup, or if there were
> multiple copies of the same program.
...
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