ZFS Mountpoints and iSCSI

Question

It seems when i create a ZFS file system with a command like 'zfs create -V 2g mypool/iscsi_vol_0' I can export it with iscsitadm. It also shows a mountpoint of '-' when I do a'zfs list'.
-bash-3.00# zfs list
NAME                       USED  AVAIL  REFER  MOUNTPOINT
mypool                    4.00G  62.4G    18K  /mypool
mypool/iscsi_vol_0     2G  62.6G  1.84G  -
mypool/iscsi_vol_1      18K  10.0G    18K  none
mypool/iscsi_vol_2     2G  64.4G    30K  -If I create a ZFS file system with a command like 'zfs create mypool/iscsi_vol_1 -o quota=10G' it gets mounted, so I issue a 'zfs set mountpoint=none mypool/iscsi_vol_1' and check if its mounted 'ls /mypool/' or 'mount' and its not, yet I still cant export it?
-bash-3.00# iscsitadm create target -b /dev/zvol/dsk/mypool/iscsi_vol_1 name-tgt1
iscsitadm: Error Failed to stat(2) backing for 'disk'What is the significance of the "-" as a mountpoint that allows the target to be exported via iSCSI?
Thanks!

Answer 1

jcasale wrote:
It seems when i create a ZFS file system with a command like 'zfs create -V 2g mypool/iscsi_vol_0' I can export it with iscsitadm. It also shows a mountpoint of '-' when I do a'zfs list'.Right, the -V makes this a "volume". It's just an empty set of blocks (with a specific size). A normal filesystem allocates space in the pool as necessary depending on files that are added. Since it's a set of blocks, you can't access it directly through a mount point. You'd have to put a filesystem on it to do that.
If I create a ZFS file system with a command like 'zfs create mypool/iscsi_vol_1 -o quota=10G' it gets mounted, so I issue a 'zfs set mountpoint=none mypool/iscsi_vol_1' and check if its mounted 'ls /mypool/' or 'mount' and its not, yet I still cant export it?iSCSI (and SCSI) give access to block devices, not filesystems. So only volumes can be used over iSCSI, not normal ZFS (or other) filesystems.
Darren