Rsync corrupted MAC on input

I am migrating my FreeNAS 7.x to a 8.x, which means copying the ZFS tank as there isn’t a tool for migrating the disks right now and upgrading them to the version of ZFS in 8.x. Kind of a pain in the butt that was made worse by the endless recurrence of an error like:

Received disconnect from xxx.xxx.xxx.xxx: 2: Packet corrupt
rsync: writefd_unbuffered failed to write 4 bytes to socket [sender]: Broken pipe (32)
rsync: connection unexpectedly closed (23734 bytes received so far) [sender]
rsync error: unexplained error (code 255) at io.c(601) [sender=3.0.7]

or something like:

Disconnecting: Packet corrupt
rsync: connection unexpectedly closed (581052724 bytes received so far) [receiver]
rsync error: error in rsync protocol data stream (code 12) at io.c(601) [receiver=3.0.8]
rsync: connection unexpectedly closed (202 bytes received so far) [generator]
rsync error: unexplained error (code 255) at io.c(601) [generator=3.0.8]

I figured my 7.x install had to be fine as I’ve been RSYNCing my server to it without error for about a year now, so the problem had to be in the new box and poking around for “packet corrupt rsync” on google was turning up a lot of *shrug* maybe bad RAM or a bad NIC. Hmmm… I tried command line push and pull from both boxes via SSH to see if I could get better results, no luck: a few files would transfer, maybe 10 seconds, maybe 5 minutes, then blop, bad packet, broken pipe, oh so informative “unexplained error” at io.c, start over. No way I was going to be able to transfer 3.5 TB 100MB at a time.

Finally I found this and checked the lovely graphical status monitor on the FreeNAS 7 box. It has 4GB of RAM, whichhas been plenty so far, but looking at the graph it was using about 95% of that memory. It had been up for 59 days so I was reluctant to reboot it, I mean uptime is a competition after all. But I took a dive and rebooted. Now, even with CIFS/SAMBA cranking some backup files simultaneously, RSYNC is running flawlessly at a nice steady 300mb/s, apparently limited by CPU (seems to be single threaded, maxing out one CPU and leaving the other idle, hmmm… problem for another day). I feel bad for doubting my FreeNAS 8 box, it was never the problem.

So if you’re getting RSYNC problems consider rebooting the server to free up RAM or even upgrading. The new box will have 12-16GB, which is about what is recommended for ZFS (1GB/TB) and things are looking pretty good. My RSYNC was running just -a –progress, no resource intensive -z option.