ZFS panic on import under VMware

[Jeremy Chadwick]

On Thu, Jun 06, 2013 at 02:10:51PM -0700, Michael Dexter wrote:
> Hello all,
> 
> 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.
> 
> The panic reports:
> 
> 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/
> 
> Any suggestions?

1. On what OS (version, etc.) was the ZFS pool originally created?

2. Was the pool originally created with compression or dedup enabled?

(Answers to both of these questions is extremely important)

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

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

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.

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...

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

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.

Otherwise, ZFS experts are going to have to help you, and will probably
require use of zdb(8) and a lot of attention.  You may get faster and
better support from Illumos/OpenIndiana or Solaris-related lists,
especially if you are able to panic those with ZFS.  I am certain they
will be **extremely** interested (folks there are responsible for ZFS as
a filesystem, not FreeBSD/FreeNAS/etc.).

-- 
| Jeremy Chadwick                                   jdc at koitsu.org |
| UNIX Systems Administrator                http://jdc.koitsu.org/ |
| Making life hard for others since 1977.             PGP 4BD6C0CB |