GEOM tasting iscsi zvols?

[John]

Hi Folks,

   I noticed (actually looked at my serial console logs :) that GEOM appears
to be tasting the zvols being exported via iscsi(istgt). For instance:

   multipath completes...

GEOM_MULTIPATH: da405 added to Z22
GEOM_MULTIPATH: da406 added to Z23
GEOM_MULTIPATH: da407 added to Z24

   load zfs...

ZFS filesystem version 5
ZFS storage pool version 28

   luns tasted...

GEOM_PART: integrity check failed (zvol/pool0/d00000003_300g_16k, MBR)
GEOM_PART: integrity check failed (zvol/pool0/d00000003_300g_16k at snap1, MBR)
GEOM_PART: integrity check failed (zvol/pool0/d00000001_300g_16k, MBR)
GEOM_PART: integrity check failed (zvol/pool0/d00000001_300g_16k at snap1, MBR)

   The zvols have never been accessed/formatted from the local system
except via the istgt daemon from the client.

   Is there a way to disable this that I've somehow missed?  man 4 GEOM
mentions "tasting" and the logic around this operation. A google search
shows a couple of similar questions - no discrete answers.

   Comments welcome.

Thanks,
John