Installation guide

Table 8–4: LSM Configuration Options (cont.)
Configuration Description
Mirrored and
striped volumes
Use mirrored and striped volumes when speed and availability
are important. LSM supports mirroring of striped plexes. This
configuration offers the improved I/O performance of striping
while also providing data availability.
The different striped plexes in a mirrored volume do not have
to be symmetrical. For instance, a three-way striped plex can
be mirrored with a two-way striped plex as long as the plex size
is the same. Reads can be serviced by any plex in a mirrored
volume. Thus, a mirrored volume provides increased read
performance. However, LSM issues writes to all plexes in a
mirrored volume. Because the writes are issued in parallel,
there is a small amount of additional overhead as the result of
a write I/O to a mirrored volume.
8.6 Implementing an LSM Configuration
After installing and licensing the LSM software (as described in the
Installation Guide), you can use the information in the following sections to
quickly get LSM up and running.
The following sections provide quick reference information to help you
reenable LSM after an installation, start up LSM for the first time, and
perform several common LSM operations. The examples provided use the
command-line interface. See the Logical Storage Manager guide for
complete information about using the command line interface, and for
information about the LSM graphical user interface and menu interface.
8.6.1 Reenabling LSM
If you are already running LSM and the rootdg disk group is already
initialized, you do not need to reenable LSM. For example, if you performed
an upgrade installation, skip this section.
If you had LSM initialized on a system before doing a full installation, you
can reenable the LSM configuration by performing the following steps:
1. Copy the /etc/volboot file from a backup:
# cp /backup/volboot /etc/volboot
2. Create the LSM special device file:
# /sbin/volinstall
3. Start the LSM daemons and volumes:
8–14 Administering the Logical Storage Manager