Panic and reboot with USB hard disk

[Bartosz Fabianowski]

With the help of some folks in #freebsd on freenode, I have since been 
able to fix this problem. Here is the solution for future reference:

There is a bug in GELI that makes it corrupt data and panic kernels when 
certain non-standard settings are used. I had set the GELI sector size 
to 8192 and the AES key length to 256. After reinitializing GELI with 
sector size 4096 and AES key length 128, the problems have vanished. 
Even under extreme I/O load to the drive, the kernel does not panic and 
no data corruptions occur.