Arch Linux

rsync 3.1.1 has two compress methods, "old" and "new". The old method (-z) depends on the internal modified zlib, while the new one (-zz) can use stock zlib.

Since Arch's rsync is built using "--with-included-zlib=no", the old compress method (-z) is unavailable, and attempting to use it results in this error:

"This rsync lacks old-style --compress due to its external zlib. Try -zz"
"Continuing without compression."

However, if I use -zz, it stops working with *older* rsync (backing up a server that has 3.1.0):

"rsync: on remote machine: --new-compress: unknown option"

So my backup script has to either add -zz depending on the remote hostname, or avoid compression entirely. Both of which, honestly, suck.