On 9/11/10 2:22 AM, Timothy Omer wrote:
>
> -for rsyncd, fulls and incrementals are the same other than the fact
> that full takes longer checking all files. The reason full is the same
> is due to it will not transfer any files in the pool that are the
> same, hence it only transfers changes... just like incrementals
> -if have 1 full and 7 incrementals, the next full will hard-link back
> to any full and incremental backups it needs to use. Therefore not all
> files will be transferred again

It's not 'any files in the pool', the server-side comparison is done against 
your last full unless you have configured incremental levels.  Any files that 
weren't in the last full get transferred, then discarded when found to match an 
existing pool file (the hashing for the filename match can't be done otherwise).

> -when an old backup comes up to expire, I guess any files that are not
> hard linked are deleted - not all of them

Yes, the nightly run removes pool files with only one link remaining (the pool 
filename).

> You said "why not just do more frequent full runs to keep the base
> more current?" - why is this different than incremental? Full and
> incremental to me just sound more logical and the extra time on the
> client to do the processing of a full I can schedule for a weekend.

Fulls rebuild and fill the complete file tree for a backup and become the next 
comparison base where incrementals just hold the differences.  If you can run 
fulls on weekends - or skew the days they run so they complete in a reasonable 
window you shouldn't need the extra hardlinks to fill incrementals.

If you use the tar or smb xfer methods, you also need frequent fulls to be sure 
you catch all the files, since those incrementals are strictly timestamp based 
and will miss new/moved files if an old timestamp is maintained.  Rsync/rsyncd 
doesn't have that issue since it actually compares directories.

-- 
   Les Mikesell
    lesmikesell AT gmail DOT com


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