ZFS deadlocks or panics

I'm trying to bild a storagebox with ZFS. Now I have some problems
which seems to be related to ZFS. Perhaps after adding disks to an
existing pool, all consoles trying to execute a command with I/O
operations freezes. Only sometimes I get a panic.

I played around with the tuning variables, proposed in
http://wiki.freebsd.org/ZFSTuningGuide
but didn't help.

The box is running -CURRENT amd64/SMP in a GENERIC configuration.
Last cvsup and build was "Fri Jun 22"

I also tried with i386 with and without SMP.

I collected some Information and uploaded it to
https://jschmidle.org/upload/

In "panic1" you can see a whole system-bootup resulting in a Panic.
"panic2" is just another lockup during bootup.
"areca" contains the information about the raid controller in use.
in "dump", I tried to create a coredump during a lockup.
"alltrace", "witness", "ps" also have been created during the lockup.
"sysctl" contains the current settings.

Can anyone recognize where the problem is coming from or is
additional information needed?

Jan