Fix Transfer Rate Drops when Transferring Data from FreeNAS 11.2 to macOS

05 Feb 2019

Problem

Somewhere between FreeNAS 11.1 U6 and 11.2 U1, a change merged from FreeBSD (some kind of network throttling) results in macOS clients having problems with a significant drop in tranfer rates.

Solution

Run sysctl net.inet.tcp.reass.maxqueuelen=4096 in a FreeNAS shell.

To make the change permanent, go to System -> Tunables in the FreeNAS WebUI. Add a variable: net.inet.tcp.reass.maxqueuelen with value 4096 and type Sysctl.

1. https://forums.freenas.org/index.php?threads/11-1u6-update-transfer-aborts-on-smb-share-mac-client.69553/post-481046
2. https://www.freebsd.org/security/advisories/FreeBSD-SA-18:08.tcp.asc