I did not experience issues using NFS and FreeNAS 8.2 on my N40L. What is the trap you are talking about ?
The only "issue" seems to be quite low data transmission speed. But as it is enough to stream Bluray image, it is not an issue for me.
Will migration from 8.2 to 8.3 affect my jail ?
The trap (specifically Trap 12) is a kernel error message. The system crashes and needs to be restarted. For me, once I got one of these trap 12's, I ould never restart the server, it would just Trap 12 during boot, the only thing I could do was reinstall.
For me, the issue was sporadic. The first time or two it happened I put it down to my relative inexperience with FreeNAS (I'm a Linux software developer by trade). I reinstalled and forgot about it. When it happened again I noted I was running transmission at the time downloading torrents. A couple days later I got the same issue again, this time also using Transmission. At this point I began to hypothesise it must be a network card driver issue or some crazy bug in Transmission (less likely as I don't know how Transmission could create a Trap 12 from inside a jail without doing something seriously scary). At that point I started using the system without Transmission hoping the problem would go away if I stay away from Transmission. This worked for a couple weeks (maybe 2 months or so?). Then randomly the machine crashed again a couple weeks ago out of the blue when I was happily browsing files over NFS. When this happened I reinstalled 8.2 YET AGAIN only to find when I woke the next day the machine had crashed again. I got mad and installed 8.3 RC1. Since then I haven't had a single issue and things seem perhaps faster than 8.2 (though it could be a placebo).
This is on 64bit, I'm not sure if 32bit would have the same issues.
Luckily I never experienced any actual data loss during these crashes.
I just wanted to bring it up just in case you run into issues.
