ZFS on root backup

Matthew Seaman m.seaman at infracaninophile.co.uk
Mon Jul 11 10:59:26 UTC 2011

On 11/07/2011 11:20, Dick Hoogendijk wrote:
> OK, so now my ZFS on root FreeBSD-8.2 system runs smoothly and I'm very
> happy being able to have ZFS (coming from solaris11), but.. what is the
> best strategy to back this fbsd system up. do I create various ZFS
> backup filesystem streams or can I easely backup the zroot pool as a
> whole? And if yes, how?
> Grateful for all the help I can get in these matters.

Well, the best backup strategy is a very site specific thing.  There's
no one-size-fits-all answer.

Suppose your machine caught fire right now.  You're always going to lose
some data -- everything that changed since the last backup.  How much
data can you afford to lose like that?  A day's worth?  A week's worth?
 Absolutely none at all?

Given your server is destroyed, how fast do you need to get it back?
Can you wait for a week in order to source replacement kit?  Or does
every second of lost uptime cost you significant amounts of money?

Now imagine the ultimate disaster scenario: typically something like --
a fully loaded jumbo jet crashes into your datacenter and everything is
completely destroyed[*].  Will your backups survive?  Can you rebuild
your system using those backups?

Suppose someone stole your backup media: can they extract all your data
from them, and does it matter if they do?

Those are the sorts of questions you need to think about when designing
a backup system.  There's nothing particularly specific about ZFS there.

What ZFS does get you in terms of backups are two things:

   1) Really easy and unlimited amounts of snap-shotting.  As well as
      making it really simple to get a coherent point-in-time backup of
      an active filesystem, they also give you a really simple 'undo'
      type functionality, so you can unwind accidental deletions and
      other user mistakes.

   2) ZFS import and export -- again, exploiting the snap-shotting
      capability, this makes it pretty easy to create a duplicate of
      your filesystem onto another host, and to update the duplicate in
      a very efficient way.



[*] As a number of companies found out to their cost, 'in the basement
of the other tower' was not sufficiently off-site to be effective.

Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
                                                  Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey     Ramsgate
JID: matthew at infracaninophile.co.uk               Kent, CT11 9PW

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