Using Serviceguard Extension for RAC, 8th Edition, March 2009

NOTE: For more information on using LVM, refer to the HP-UX Managing Systems and
Workgroups manual.
Building Mirrored Logical Volumes for RAC with LVM Commands
After you create volume groups and define physical volumes for use in them, you define mirrored
logical volumes for data, logs, and control files. It is recommended that you use a shell script to
issue the commands described in the next sections. The commands you use for creating logical
volumes vary slightly depending on whether you are creating logical volumes for RAC redo log
files or for use with Oracle data.
Creating Mirrored Logical Volumes for RAC Redo Logs and Control Files
Create logical volumes for use as redo log and control files by selecting mirror consistency
recovery. Use the same options as in the following example:
# lvcreate -m 1 -M n -c y -s g -n redo1.log -L 28 /dev/vg_ops
The -m 1 option specifies single mirroring; the -M n option ensures that mirror write cache
recovery is set off; the -c y means that mirror consistency recovery is enabled; the -s g means
that mirroring is PVG-strict, that is, it occurs between different physical volume groups; the -n
redo1.log option lets you specify the name of the logical volume; and the -L 28 option allocates
28 megabytes.
NOTE: It is important to use the -M n and -c y options for both redo logs and control files.
These options allow the redo log files to be resynchronized by SLVM following a system crash
before Oracle recovery proceeds. If these options are not set correctly, you may not be able to
continue with database recovery.
If the command is successful, the system will display messages like the following:
Logical volume “/dev/vg_ops/redo1.log” has been successfully created
with character device “/dev/vg_ops/rredo1.log”
Logical volume “/dev/vg_ops/redo1.log” has been successfully extended
NOTE: The character device file name (also called the raw logical volume name) is used by the
Oracle DBA in building the RAC database.
Creating Mirrored Logical Volumes for RAC Data Files
Following a system crash, the mirrored logical volumes need to be resynchronized, which is
known as “resilvering”.
If Oracle does not perform “resilvering” of RAC data files that are mirrored logical volumes,
choose a mirror consistency policy of “NOMWC”. This is done by disabling mirror write caching
and enabling mirror consistency recovery. With “NOMWC”, SLVM performs the
resynchronization.
Create logical volumes for use as Oracle data files by using the same options as in the following
example:
# lvcreate -m 1 -M n -c y -s g -n system.dbf -L 408 /dev/vg_ops
The -m 1 option specifies single mirroring; the -M n option ensures that mirror write cache
recovery is set off; the -c y means that mirror consistency recovery is enabled; the -s g means
that mirroring is PVG-strict, that is, it occurs between different physical volume groups; the -n
system.dbfoption lets you specify the name of the logical volume; and the -L 408 option
allocates 408 megabytes.
If Oracle performs the “resilvering” of RAC data files that are mirrored logical volumes, choose
a mirror consistency policy of “NONE” by disabling both mirror write caching and mirror
82 Serviceguard Configuration for Oracle 9i RAC