ZFS on root backup
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
PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate
JID: matthew at infracaninophile.co.uk Kent, CT11 9PW
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