Hi, we are in the middle of an investigation of a partial-write issue and found a bug that can lead to message loss in some circumstances, even when reliable diskbuffer is used. We marked this bug as release critical. Fortunately we fixed the issue a few minutes ago, so we are going to release 3.17.2 that contains the fix ( https://github.com/balabit/syslog-ng/pull/2224 ). We don't have an automated testcase for this, actually it is in progress(this is why we didn't catch the bug), but sharing the manual reproduction: * listen with netcat (and use pv tool to make partial write happen) nc -l 61002 | pv -L 40 * run syslog-ng with the following config: @version: 3.17 options { time_reopen(3); stats_level(1); }; source s_network { network(ip("127.0.0.1") port(5555)); }; destination d_network { network("127.0.0.1" disk_buffer(mem-buf-size(1000) disk-buf-size(1048576) reliable(yes) dir('/tmp/dq')) ip_protocol(4) port(6666) so-sndbuf(4096)); }; log { source(s_network); destination(d_network); flags(flow-control); }; * send logs loggen -r 100000 -I 200 127.0.0.1 10001 --inet * wait a few seconds then stop netcat * result: syslog-ng will drops all the incoming messages regards, Laszlo Budai