ZFS panic on import under VMware

[Michael Dexter]

Requested details included inline:

>> I have encountered a FreeNAS under VMware system that gives "ONLINE"
>> status for a pool with 'zfs import' but panics when a -f import is
>> done under FreeNAS 8.3 x64, FreeBSD 10 and Solaris 11 live DVD. The
>> host filesystem passes all checks.
>> Stopped at traverse_prefetch_metadata+0x44: movq 0x50(%rax),%rcx
>> I have posted screen shots of the import, panic and backtrace output:
>> http://cft.lv/zfs/2013-07-06/
>
> 1. On what OS (version, etc.) was the ZFS pool originally created?

FreeNAS 8.2

> 2. Was the pool originally created with compression or dedup enabled?
> (Answers to both of these questions is extremely important)

Dedup: never enabled
Compression: Yes (Believe FreeNAS Default, guessing lzjb)

> 3. How much memory are you allocating to the VMware instance?  (This is
> in partial relation to question #2)

6GB, up to 10GB when attempting to re-import

> 4. On what OS (version, etc.) are the panic/backtrace screenshots from?
> It looks to me like FreeBSD 10.x.

Correct. amd64. Panics with Solaris 11.1 & FreeNAS 8.3. No saved traces

> 5. Is there a reason you didn't try FreeBSD 9.1-RELEASE?  The state of
> FreeBSD 10.x (head/CURRENT) is usually in fluctuation, you should try
> something other than head.

Will try 9.1R

> 6. You're using VMware Workstation; where did the source ZFS pool come
> from?  Do you have physical disks attached to the machine and are using
> the "Use a physical disk" feature?  If you're using "disk images" made
> by something, what did you use?  Please provide all the details, how you
> did it, etc...

VMware ESXi 5.1 with no storage. All from HUS110 iSCSI, mounted as VMFS5 
Datastores. The failing disks are vmdk files in virtual disk mode which 
were created when installing FreeNAS.

> 7. Is there some reason you cannot try this on bare metal?

VMware does not appear to fully support ZFS pass-through. Not easy to 
convert two, 2TB images. Suggestions?

> 8. On FreeBSD 9.x (see above) or 10.x, during boot, drop to the loader
> prompt and issue "set vfs.zfs.prefetch_disable=1" followed by "boot".
> See if that has any impact during the "zpool import" phase.

Results in Fatal trap 12 on FreeBSD 10 and will try 9.X ASAP.

Thanks!

Michael