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|Oracle Solaris ZFS Administration Guide Oracle Solaris 10 1/13 Information Library|
In the following example, a 5-GB ZFS volume, tank/vol, is created:
# zfs create -V 5gb tank/vol
When you create a volume, a reservation is automatically set to the initial size of the volume so that unexpected behavior doesn't occur. For example, if the size of the volume shrinks, data corruption might occur. You must be careful when changing the size of the volume.
In addition, if you create a snapshot of a volume that changes in size, you might introduce inconsistencies if you attempt to roll back the snapshot or create a clone from the snapshot.
For information about file system properties that can be applied to volumes, see Table 5-1.
You can display a ZFS volume's property information by using the zfs get or zfs get all command. For example:
# zfs get all tank/vol
A question mark (?) displayed for volsize in the zfs get output indicates an unknown value because an I/O error occurred. For example:
# zfs get -H volsize tank/vol tank/vol volsize ? local
An I/O error generally indicates a problem with a pool device. For information about resolving pool device problems, see Identifying Problems With ZFS Storage Pools.
If you are using a Solaris system with zones installed, you cannot create or clone a ZFS volume in a non-global zone. Any attempt to do so will fail. For information about using ZFS volumes in a global zone, see Adding ZFS Volumes to a Non-Global Zone.
During installation of a ZFS root file system or a migration from a UFS root file system, a swap device is created on a ZFS volume in the ZFS root pool. For example:
# swap -l swapfile dev swaplo blocks free /dev/zvol/dsk/rpool/swap 253,3 16 8257520 8257520
During installation of a ZFS root file system or a migration from a UFS root file system, a dump device is created on a ZFS volume in the ZFS root pool. The dump device requires no administration after it is set up. For example:
# dumpadm Dump content: kernel pages Dump device: /dev/zvol/dsk/rpool/dump (dedicated) Savecore directory: /var/crash/ Savecore enabled: yes
If you need to change your swap area or dump device after the system is installed, use the swap and dumpadm commands as in previous Solaris releases. If you need to create an additional swap volume, create a ZFS volume of a specific size and then enable swap on that device. Then, add an entry for the new swap device in the /etc/vfstab file. For example:
# zfs create -V 2G rpool/swap2 # swap -a /dev/zvol/dsk/rpool/swap2 # swap -l swapfile dev swaplo blocks free /dev/zvol/dsk/rpool/swap 256,1 16 2097136 2097136 /dev/zvol/dsk/rpool/swap2 256,5 16 4194288 4194288
Do not swap to a file on a ZFS file system. A ZFS swap file configuration is not supported.
For information about adjusting the size of the swap and dump volumes, see Adjusting the Sizes of Your ZFS Swap Device and Dump Device.
You can easily create a ZFS volume as an iSCSI target by setting the shareiscsi property on the volume. For example:
# zfs create -V 2g tank/volumes/v2 # zfs set shareiscsi=on tank/volumes/v2 # iscsitadm list target Target: tank/volumes/v2 iSCSI Name: iqn.1986-03.com.sun:02:984fe301-c412-ccc1-cc80-cf9a72aa062a Connections: 0
After the iSCSI target is created, set up the iSCSI initiator. For more information about Solaris iSCSI targets and initiators, see Chapter 12, Configuring Oracle Solaris iSCSI Targets (Tasks), in System Administration Guide: Devices and File Systems.
Note - Solaris iSCSI targets can also be created and managed with the iscsitadm command. If you set the shareiscsi property on a ZFS volume, do not use the iscsitadm command to also create the same target device. Otherwise, you create duplicate target information for the same device.
A ZFS volume as an iSCSI target is managed just like any other ZFS dataset. However, the rename, export, and import operations work a little differently for iSCSI targets.
When you rename a ZFS volume, the iSCSI target name remains the same. For example:
# zfs rename tank/volumes/v2 tank/volumes/v1 # iscsitadm list target Target: tank/volumes/v1 iSCSI Name: iqn.1986-03.com.sun:02:984fe301-c412-ccc1-cc80-cf9a72aa062a Connections: 0
Exporting a pool that contains a shared ZFS volume causes the target to be removed. Importing a pool that contains a shared ZFS volume causes the target to be shared. For example:
# zpool export tank # iscsitadm list target # zpool import tank # iscsitadm list target Target: tank/volumes/v1 iSCSI Name: iqn.1986-03.com.sun:02:984fe301-c412-ccc1-cc80-cf9a72aa062a Connections: 0
All iSCSI target configuration information is stored within the dataset. Like an NFS shared file system, an iSCSI target that is imported on a different system is shared appropriately.