Best procedure for full backup of live system

Polytropon freebsd at
Fri Oct 16 15:47:56 UTC 2009

On Thu, 15 Oct 2009 21:47:57 -0600 (MDT), Warren Block <wblock at> wrote:
> Just a general note: backup to a hard drive isn't bad, but it's not the 
> same as removable media.  One failure can kill all of your backups...

That's why it's often a good choice two have at least two
hard disks (maybe external ones) for backup, so if one
fails (which seems to be a problem of "modern" disks
rather than older ones), there's still an intact backup
on the other one (or on one of the others).

> Backup in general is making copies of information 
> you won't need as long as you have a backup of it.a

A wise summary. :-)

> dump(8) doesn't do all sectors, just ones used by the filesystem.
> Also, dump doesn't cross filesystems.  In a typical FreeBSD install, /, 
> /var, and /usr are separate filesystems.  A dump of / won't get them all 
> at once.

The dump utility is good when you want to work partition-wise.
If you have a setting where everything goes into a big /, dumping
it will get all data - from that partition. Slices and MBR are
out of dump's scope.

> > My server should boot fine with the FreeBSD CDROM (fixit), because it
> > uses a subset of the GENERIC kernel device drivers.
> If you can, try that before an actual emergency.

Furthermore, it's good to check backups regularly. A defective
backup is NO backup. If data doesn't restore as intended (e. g.
to a testing system), then...?

A situation that many of you surely have come across, as I have:
Operator: The hard disk crashed, we need to restore from backups.
Customer: Of course I have backups! Here!
Customer hands over three tapes.
Operator starts restore with tape #1.
Operator: First tape is through. Good. Next one.
Computer displays rroor reading /dev/nsa0: Tape is defect, cannot read.
Operator: Do you have other set of tapes? This #2 is defective.
Customer: Yes! Tape #3!
Operator: I need a working tape #2.
Customer: BUT I *HAVE* BACKUPS!!!

Testing the backups may take some time, I agree, but it's mostly
worth it - it's worth as much as your data is to you.

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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