[Borgbackup] Recreate segments after changing max_segment_size

[Thomas Waldmann]

> e.g. given sements 0, 1, 2, 3 will be concatenated to segement 0
> 
> tail -c +9 data/0/1 >> data/0/0
> tail -c +9 data/0/2 >> data/0/0
> tail -c +9 data/0/3 >> data/0/0
> rm data/0/[123]
> rm hints.* index.* integrity.*

A borg repo is not supposed to be used like that.

Also, I don't think anyone wants to support dealing with a borg repo on 
that level - at least not me. :-)

> Is there any risk doing this?

The risk is that you accidentally damage your repo, lose data, cause 
inconsistencies. The other risk is that other people read this and try 
this (maybe less carefully / knowledgeable than you).

>> I have several borg repos with small segment sizes of 5 MB. I would like
>> to recreate the segments to a larger size for better repo backup with
>> rsync/rclone.

Why should it be "better" with a larger size?

The 500MiB default of borg 1.1.x is primarily optimized for local repos.

Doing some sync-to-remote could rather improve by using a 
smaller-than-default segment size.

>> Without the option "--recompress always" the smaller segments are not
>> repacked to larger segments.

Not sure if it really needs to be "always" (and not sure if "always" 
causes a major slowdown with many archives, really recompressing the 
same stuff again and again).

You could try just going to another algorithm than the one you used for 
the 5MB segments.


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