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Backups of backups

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From: "Neal H. Walfield" <neal@walfield.org>
Date: Sat, 29 Jul 2017 11:02:12 +0200

   Hi,
   
   My current backup of backup solution is to use 'zfs send' to replicate
   my backup to an offsite location.  This works great, but has the
   limitation that the offsite server has to have the same amount of disk
   space as the onsite server.
   
   Does obnam have any support for backups of backups?  For instance, I
   think it would be cool to just propagate a particular generation?
   Then, my offsite backup might only have the last few backups, but the
   onsite backup could keep a longer history.
   
   Thanks!
   
   :) Neal
   
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   obnam-support mailing list
   obnam-support@obnam.org
   http://listmaster.pepperfish.net/cgi-bin/mailman/listinfo/obnam-support-obnam.org
From: SanskritFritz <sanskritfritz@gmail.com>
Date: Sat, 29 Jul 2017 13:06:20 +0200

   If you had enough space on the offsite system, you can upload the whole
   repo and then later you just have to incrementally rsync the difference. I
   don't think Obnam sports such a feature to actually split a repo.
   
   
   
   
   
   
   
   On Sat, Jul 29, 2017 at 11:02 AM, Neal H. Walfield <neal@walfield.org>
   wrote:
   
   > Hi,
   >
   > My current backup of backup solution is to use 'zfs send' to replicate
   > my backup to an offsite location.  This works great, but has the
   > limitation that the offsite server has to have the same amount of disk
   > space as the onsite server.
   >
   > Does obnam have any support for backups of backups?  For instance, I
   > think it would be cool to just propagate a particular generation?
   > Then, my offsite backup might only have the last few backups, but the
   > onsite backup could keep a longer history.
   >
   > Thanks!
   >
   > :) Neal
   >
   > _______________________________________________
   > obnam-support mailing list
   > obnam-support@obnam.org
   > http://listmaster.pepperfish.net/cgi-bin/mailman/listinfo/
   > obnam-support-obnam.org
   >
From: Lars Wirzenius <liw@liw.fi>
Date: Sat, 29 Jul 2017 16:16:25 +0300

   On Sat, Jul 29, 2017 at 11:02:12AM +0200, Neal H. Walfield wrote:
   > Hi,
   > 
   > My current backup of backup solution is to use 'zfs send' to replicate
   > my backup to an offsite location.  This works great, but has the
   > limitation that the offsite server has to have the same amount of disk
   > space as the onsite server.
   > 
   > Does obnam have any support for backups of backups?  For instance, I
   > think it would be cool to just propagate a particular generation?
   > Then, my offsite backup might only have the last few backups, but the
   > onsite backup could keep a longer history.
   
   Obnam doesn't support that. If you want to have backups in two
   locations, why not run Obnam twice, once per location?
From: "Neal H. Walfield" <neal@walfield.org>
Date: Mon, 31 Jul 2017 17:26:09 +0200

   On Sat, 29 Jul 2017 13:06:20 +0200,
   SanskritFritz wrote:
   > If you had enough space on the offsite system, you can upload the whole repo and then later you just have to
   > incrementally rsync the difference. I don't think Obnam sports such a feature to actually split a repo.
   
   Thanks for the suggestion.  But, I suspect that 'zfs send' is probably
   better (zfs send doesn't have to stat every file to find differences).
   
   :) Neal
   
   
   _______________________________________________
   obnam-support mailing list
   obnam-support@obnam.org
   http://listmaster.pepperfish.net/cgi-bin/mailman/listinfo/obnam-support-obnam.org
From: "Neal H. Walfield" <neal@walfield.org>
Date: Mon, 31 Jul 2017 17:28:01 +0200

   On Sat, 29 Jul 2017 15:16:25 +0200,
   Lars Wirzenius wrote:
   > > My current backup of backup solution is to use 'zfs send' to replicate
   > > my backup to an offsite location.  This works great, but has the
   > > limitation that the offsite server has to have the same amount of disk
   > > space as the onsite server.
   > > 
   > > Does obnam have any support for backups of backups?  For instance, I
   > > think it would be cool to just propagate a particular generation?
   > > Then, my offsite backup might only have the last few backups, but the
   > > onsite backup could keep a longer history.
   > 
   > Obnam doesn't support that. If you want to have backups in two
   > locations, why not run Obnam twice, once per location?
   
   Unfortunately, it is cheap to send data, but expensive to read it.  If
   I correctly understand how obnam works, then obnam does a lot of
   reading to compare data even if nothing has changed.  (If that's not
   true, then please correct me!)
   
   Thanks!
   
   :) Neal
   
   _______________________________________________
   obnam-support mailing list
   obnam-support@obnam.org
   http://listmaster.pepperfish.net/cgi-bin/mailman/listinfo/obnam-support-obnam.org
From: Lars Wirzenius <liw@liw.fi>
Date: Tue, 1 Aug 2017 12:01:19 +0300

   On Mon, Jul 31, 2017 at 05:28:01PM +0200, Neal H. Walfield wrote:
   > Unfortunately, it is cheap to send data, but expensive to read it.  If
   > I correctly understand how obnam works, then obnam does a lot of
   > reading to compare data even if nothing has changed.  (If that's not
   > true, then please correct me!)
   
   Obnam compares the file metadata (owner, group, mtime, size, etc) to
   decide there's a need to make a backup. Reading through all the files
   on every backup run would be so slow it'd be silly to do it that way.
From: Andrew Ruthven <andrew@etc.gen.nz>
Date: Tue, 01 Aug 2017 19:43:44 +1200

   On Mon, 2017-07-31 at 17:26 +0200, Neal H. Walfield wrote:
   > On Sat, 29 Jul 2017 13:06:20 +0200,
   > SanskritFritz wrote:
   > > If you had enough space on the offsite system, you can upload the
   > > whole repo and then later you just have to
   > > incrementally rsync the difference. I don't think Obnam sports such
   > > a feature to actually split a repo.
   > 
   > Thanks for the suggestion.  But, I suspect that 'zfs send' is
   > probably
   > better (zfs send doesn't have to stat every file to find
   > differences).
   
   How about putting your obnam repo on a zfs partition, then use `zfs
   send` to replicate the repo to your remote location?
   
   Cheers,
   Andrew