-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Peter Wright wrote: > On 21/01 10:48:50, Tino Schwarze wrote: >> On Wed, Jan 21, 2009 at 02:08:31PM +0900, Peter Wright wrote: >>>> An incremental backup will transfer changed data from the >>>> previous full or incremental of a lower level. >>> Can backuppc be configured to transfer changed data from the previous >>> incremental of the *same* level, or would this require a patch? >> Why would you want to do that? The previous incremental of the same >> level is a lot older and you'd need to transfer a lot more changes. > > Take my words in the context of responding to Adam - though perhaps I > could have put it more clearly :). > > Adam stated that "An incremental backup will transfer changed data > from the previous full or incremental of a lower level." > > What I was thinking is that if my highest priority was minimising > bandwidth per backup, why shouldn't I be able to configure backuppc to > *only* do incrementals and consider them all to be the same "level"?
Since "previous full or incremental of a lower level" is not the same as "all incremental on the *same* level"... Each transfer would in effect be compared to the previous full, which will get progressively worse (based on your goal of bandwidth usage minimisation). > But I suspect I've probably misunderstood one or more key backuppc > principles, especially re: what the "levels" really mean. > >> In default configuration (IIRC), your backups with weekly full would >> look like this: > [ snip description ] >> The second level-1 incremental will transfer all changes since the >> full backup. > > Thanks for the clarification - that was how I thought it worked, but > it's good to make sure. > > My key issue is that if I'm interested in bandwidth minimisation above > all else, why would I want to do anything other than > incremental-since-the-most-recent-previous-incremental, regardless of > the "level" concept? Actually, it is the opposite. If bandwidth minimisation is your only concern, then every backup should be a full..... Since each backup will only transfer the changed portions of existing files, or new files, compared to the previous (full) backup. This will minimise your bandwidth usage. > As I understand Holger's earlier response, the major (only?) downside > is the cost of building the backup view - and I can certainly see how > that'd become significant after a while. > > I suspect I've got my brain too hooked into the rsnapshot model > (http://www.rsnapshot.org/) and I'm not quite understanding the > different philosophy of backuppc. I presume you were doing a "full" backup each and every time using rsnapshot... ie, you didn't tell rsync to ignore files based on the modification date/time. So rsnapshot doesn't have any concept of full/incremental, since every backup is a full. You just need to carry that idea forward, and ignore the additional "feature" of incremental backups that backuppc offers. Hope that helps... Personally, I have a backuppc which never deletes a backup, it currently has over 800 backups for each host. I started with your mistake, of doing a full + forever incremental, but once I realised my error, now do a full, 3 incrementals, and another full, etc... The incremental's are done to reduce the load (and hence time) on the machines being backed up. Regards, Adam - -- Adam Goryachev Website Managers www.websitemanagers.com.au -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkl5Vw0ACgkQGyoxogrTyiUnMwCeNVe//jNblflY9VUOh308hYmV yD0An3BGkobWWxEfmVJ8n3K2jnF7y52p =0xFd -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword _______________________________________________ BackupPC-users mailing list [email protected] List: https://lists.sourceforge.net/lists/listinfo/backuppc-users Wiki: http://backuppc.wiki.sourceforge.net Project: http://backuppc.sourceforge.net/
