Creating a New Boot Environment From a ZFS Root Pool

You can either create a new ZFS boot environment within the same root pool or on a new root pool. This section contains the following overviews:

• Creating a New Boot Environment Within the Same Root Pool

• Creating a New Boot Environment on Another Root Pool

Creating a New Boot Environment Within the Same Root Pool

When creating a new boot environment within the same ZFS root pool, the lucreate command creates a snapshot from the source boot environment and then a clone is made from the snapshot. The creation of the snapshot and clone is almost instantaneous and the disk space used is minimal. The amount of space ultimately required depends on how many files are replaced as part of the upgrade process. The snapshot is read-only, but the clone is a read-write copy of the snapshot. Any changes made to the clone boot environment are not reflected in either the snapshot or the source boot environment from which the snapshot was made.

When the current boot environment resides on the same ZFS pool, the -p option is omitted.

The following figure shows the creation of a ZFS boot environment from a ZFS root pool. The slice c0t0d0s0 contains a the ZFS root pool, rpool. In the lucreate command, the -n option assigns the name to the boot environment to be created, new-zfsBE. A snapshot of the original root pool is created rpool@new-zfsBE. The snapshot is used to make the clone that is a new boot environment, new-zfsBE. The boot environment, new-zfsBE, is ready to be upgraded and activated.

Figure 10-3 Creating a New Boot Environment on the Same Root Pool

Example 10-3 Creating a Boot Environment Within the Same ZFS Root Pool

This example shows the same command as in the figure. It creates a new boot environment in the same root pool. The lucreate command names the currently running boot environment with the -c zfsBE option, and the -n new-zfsBE creates the new boot environment. The zfs list command shows the ZFS datasets with the new boot environment and snapshot.

# lucreate -c zfsBE -n new-zfsBE
# zfs list
NAME                                   USED  AVAIL  REFER  MOUNTPOINT
rpool                                     11.4G  2.95G    31K  /rpool
rpool/ROOT                                4.34G  2.95G    31K  legacy
rpool/ROOT/new-zfsBE                      4.34G  2.95G  4.34G  /
rpool/dump                                2.06G  5.02G    16K  -
rpool/swap                                5.04G  7.99G    16K  -

Creating a New Boot Environment on Another Root Pool

You can use the lucreate command to copy an existing ZFS root pool into another ZFS root pool. The copy process might take some time depending on your system.

The following figure shows the zpool command that creates a ZFS root pool, rpool2, on c0t1d0s5 because a bootable ZFS root pool does not yet exist. The lucreate command with the -n option assigns the name to the boot environment to be created, new-zfsBE. The -p option specifies where to place the new boot environment.

Figure 10-4 Creating a New Boot Environment on Another Root Pool

Example 10-4 Creating a Boot Environment on a Different ZFS Root Pool

This example shows the same commands as in the figure which create a new root pool and then a new boot environment in the newly created root pool. In this example, the zpool create command creates rpool2. The zfs list command shows that no ZFS datasets are created in rpool2. The datasets are created with the lucreate command.

# zpool create rpool2 c0t2d0s5
# zfs list
NAME                                   USED  AVAIL  REFER  MOUNTPOINT
rpool                                     11.4G  2.95G    31K  /rpool
rpool/ROOT                                4.34G  2.95G    31K  legacy
rpool/ROOT/new-zfsBE                      4.34G  2.95G  4.34G  /
rpool/dump                                2.06G  5.02G    16K  -
rpool/swap                                5.04G  7.99G    16K  -

The new ZFS root pool, rpool2, is created on disk slice c0t2d0s5.

# lucreate -n new-zfsBE -p rpool2
# zfs list
NAME                                   USED  AVAIL  REFER  MOUNTPOINT
rpool                                     11.4G  2.95G    31K  /rpool
rpool/ROOT                                4.34G  2.95G    31K  legacy
rpool/ROOT/new-zfsBE                      4.34G  2.95G  4.34G  /
rpool/dump                                2.06G  5.02G    16K  -
rpool/swap                                5.04G  7.99G    16K  -

The new boot environment, new-zfsBE, is created on rpool2 along with the other datasets, ROOT, dump and swap. The boot environment, new-zfsBE, is ready to be upgraded and activated.