+Ganti's extstorage provider doesn't support drbd target. But, lvm emulation scripts are sufficiant enough
+to create -t drdb instance or convert plain (created on zfs thanks to wrappers ;-) to drdb.
+
+
+KNOWN BUGS for extstorage
+
+- gnt-backup export doesn't work because extstorage snapshoot hook are not available
+- gnt-instance move works from somewhere to zfs, but not from zfs to somewhere
+
+
+KNOWN BUGS for using -t plain on top of zfs
+
+- cron/daily-block-snapshot snapshots are not correctly renamed