[CentOS] Need help to fix bug in rsync

Wed Mar 25 18:15:27 UTC 2020
Simon Matter <simon.matter at invoca.ch>

> On Wed, 2020-03-25 at 14:39 +0000, Leroy Tennison wrote:
>> Since you state that using -z is almost always a bad idea, could you
>> provide the rationale for that?  I must be missing something.
> I think the "rationale" is that at some point the
> compression/decompression takes longer than the time reduction from
> sending a compressed file.  It depends on the relative speeds of the
> machines and the network.
> You have most to gain from compressing large files, but if they are
> already compressed, then you have nothing to gain from just doing small
> files.
> It obviously depends on your network speed and if you have a metered
> connection, but does anyone really have such an ancient network
> connection still these days - I mean if you have fast enough machines
> at both ends to do rapid compression/decompression, it seems unlikely
> that you will have a damp piece of string connecting them.

I really don't understand the discussion here. What is wrong with using -z
with rsync? We're using rsync with -z for backups and just don't want to
waste bandwidth for nothing. We have better use for our bandwidth and it
makes quite a difference when backing up terabytes of data.

The only reason why I asked for help is because we don't want to double
compress data which is already compressed. This is what currently is
broken in rsync without manually specifying a skip-compress list. Fixing
it would help all those who don't know it's broken now.