Rsync destination to TrueNAS


Well-Known Member
Jul 26, 2013
cPanel Access Level
Root Administrator
I was attempting to set up an rsync destination on a TrueNAS server via SSH but I can never get the validation to complete successfully. I keep getting an error "could not upload test file: child exited with code 1".

I changed the destination to a different Linux server and it worked right away. Anyone else successfully used TrueNAS for an Rsync via SSH destination?

Best regards,


Oct 28, 2021
cPanel Access Level
DataCenter Provider
TrueNAS shipped rsync that is compiled with only system zlib (external zlib) and without bundled zlib (‑‑with-included-zlib=no). Whereas most distro still shipped with rsync's custom zlib due to the interoperability reasons.

[[email protected] ~]# rsync --compress TESTFILE [email protected]:./
rsync: This rsync lacks old-style --compress due to its external zlib.  Try -zz.
rsync error: syntax or usage error (code 1) at main.c(1592) [server=3.1.3]
rsync: connection unexpectedly closed (0 bytes received so far) [sender]
rsync error: error in rsync protocol data stream (code 12) at io.c(226) [sender=3.1.2]
Source: CentOS Linux release 7.9.2009 with rsync 3.1.2-10.el7
Destination: TrueNAS-12.0-U5.1 with rsync 3.1.3_2

When sending from CentOS rsync "--with-included-zlib=yes" to TrueNAS rsync "--with-included-zlib=no" using old style compression --compress, --old-compress, -z, the transfer will fail but in reverse, TrueNAS rsync will fallback to non compression transfer to CentOS
To use compression in rsync 3.1.x, --new-compress , -zz should be used when transfering to rsync without bundled zlib.
When both ends are at least rsync 3.2.0, a negotiation phase is added to pick suitable compression but AlmaLinux 8 still ship with 3.1.3

possible solution, compile/repalce truenas's rsync with included zlib or cpanel update backup rsync to not use compression or use use -zz
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