Hi, Adam Goryachev wrote on 2008-09-04 08:55:51 +1000 [Re: [BackupPC-users] Backup through slow line?]: > [...] > BTW, 2 x rsync incrementals of the same level will transfer more data > than one full + one incremental. So for example, doing 6 incrementals > followed by a full backup can in fact transfer a lot more data than > doing 7 full backups.
a while ago, rsync incrementals used to be based on the last backup of the next lower level (i.e. full backup for level 1 incremental), while rsync full backups were based on the last backup of any level (i.e. the previous backup). Craig was considering changing this so that any rsync backup would always be based on the previous backup. I don't know if this has happened yet (can't find anything in the 3.1.0 changelog), or even if Craig is still considering it. I would argue that for a full backup, it is ok to base it on the previous backup (there is no risk to the integrity, and it will probably transfer less data), while for an incremental the possibility of missing changes might be mitigated by referencing the previous backup of next lower level rather than the previous backup (but there are no guarantees, so it's only a vague possibility; then again, what other meaning do multilevel rsync incremental backups have?) - meaning I probably wouldn't change anything. Presuming nothing has changed (yet), it would in fact be optimal (regarding bandwidth) to use alternating full and incremental backups. Nevertheless, it depends on the individual situation if "a bit less bandwidth" is worth "much more disk accesses". Regards, Holger ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ BackupPC-users mailing list BackupPC-users@lists.sourceforge.net List: https://lists.sourceforge.net/lists/listinfo/backuppc-users Wiki: http://backuppc.wiki.sourceforge.net Project: http://backuppc.sourceforge.net/
