Re: [rdiff-backup-users] how to shrink/purge/truncate the metadata file (and the file_statistics file)?

[=JeffH]

Thanks Adrian.

> Are you sure that --remove-older-than is actually completing?

yes.

> If there is more
> than one increment to be removed at a time and the --force switch is not used
> then the increments will not be removed.

yes, and rdiff-backup immediately tells you this.

> You might want to do a
> rdiff-backup -l /backup/dir to see if in fact the increments have been 
removed.

yes, the increments were removed. And your questions imply that the metadata 
and file_statistics files should indeed be shrink/purge/truncated.

Apologies for my somewhat lame original question. I'm not very familiar with 
the details of how rdiff-backup works under the hood.


So, I removed yet more increments (all but the current mirror), did a 
--check-destination-dir, and then did another backup, which completed 
successfully.

However, in retrospect, I was confused wrt the actual sizes of the metadata and 
file_statistics files -- upon further examination, they are orders of magnitude 
smaller than I'd thought: megabytes rather than gigabytes.

I'm now wondering if part of what went wrong (my backup disk filled up 
unexpectedly) was that I'd made enough large changes on the source disk (I 
"shrank" a VM's virtual disk by 10s of gigs, plus I'd had a prior backup get a 
read error on a large .mp3 directory), that there essentially wasn't overall 
enough free space on the backup disk to house the both the VM's incrementally 
changed virtual disk files (10s of gigs) plus adding back into the mix all the 
previously-deleted .mp3 files (which, even tho they weren't present in the 
"current mirror", they /were/ present in prior "increments").

So this begs the question of how much headroom should the backup disk have in 
comparison to the source disk(s)?  My (current) backup disk is only somewhat 
larger than the amount of source data I have to backup.

After this, I'm thinking that it ought to be significantly larger.

Is there a rule of thumb for how much larger the backup disk ought to be in 
comparison to the overall aggregate size of the backed up source data ?

thanks,

=JeffH