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.

As data within the active dataset changes, the snapshot consumes space by continuing to reference the old data. As a result, the snapshot prevents the data from being freed back to the pool. For more information about snapshots, see Chapter 7, Working With ZFS Snapshots and Clones, in Solaris ZFS Administration Guide.

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

Figure 11–2 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 11–2 Creating a New Boot Environment on the Same Root Pool

Example 11–3 Creating a Boot Environment Within the Same ZFS Root Pool

This example shows the same command as in Figure 11–2 that 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
AME                        USED  AVAIL  REFER  MOUNTPOINT 
rpool                      9.29G  57.6G    20K  /rpool
rpool/ROOT                 5.38G  57.6G    18K  /rpool/ROOT
rpool/ROOT/zfsBE           5.38G  57.6G   551M  
rpool/ROOT/zfsBE@new-zfsBE 66.5K      -   551M  -
rpool/ROOT/new-zfsBE       5.38G  57.6G   551M  /tmp/.alt.luupdall.110034
rpool/dump                 1.95G      -  1.95G  - 
rpool/swap                 1.95G      -  1.95G  - 

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.

Figure 11–3 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 11–3 Creating a New Boot Environment on Another Root Pool

Example 11–4 Creating a Boot Environment on a Different ZFS Root Pool

This example shows the same commands as in Figure 11–3 that 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 
rpool2                           9.29G    57.6G     20K   /rpool2 
rpool                            9.29G    57.6G     20K   /.new.lulib.rs.109262
rpool/ROOT                       5.46G    57.6G     18K   legacy
rpool/ROOT/zfsBE                 5.46G    57.6G   551M  
rpool/dump                       3.99G        -   3.99G   - 
rpool/swap                       3.99G        -   3.99G   - 

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 
rpool2                           9.29G    57.6G     20K   /rpool2 
rpool2/ROOT/                     5.38G    57.6G     18K   /rpool2/ROOT 
rpool2/ROOT/new-zfsBE            5.38G    57.6G    551M   /tmp/.new.luupdall.109859
rpool2/dump                      3.99G        -   3.99G   - 
rpool2/swap                      3.99G        -   3.99G   - 
rpool                            9.29G    57.6G     20K   /.new.lulib.rs.109262
rpool/ROOT                       5.46G    57.6G     18K   legacy
rpool/ROOT/zfsBE                 5.46G    57.6G   551M  
rpool/dump                       3.99G        -   3.99G   - 
rpool/swap                       3.99G        -   3.99G   - 

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.