Using Serviceguard Extension for RAC, 9th Edition, September 2010

NOTE: With LVM 2.1 and above, mirror write cache (MWC) recovery can be set to ON for RAC
Redo Logs and Control Files volumes. Example:
# lvcreate -m 1 -M y -s g -n redo1.log -L 408 /dev/vg_ops
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.”
On node and cluster-wide failures, when SLVM mirroring is used and Oracle resilvering is
available, the recommendation is no mirror resynchronization (NONE) for the datafiles because
Oracle would perform resilvering on the datafiles based on the redo log.
If Oracle resilvering is not available, the mirror recovery policy should be set to either full mirror
resynchronization (NOMWC) or fast resynchronization (MWC) . For more information on using
NOMWC and MWC, refer to the HP-UX System Administrator's Guide: Logical Volume Management
HP-UX 11i Version 3 on www.hp.com/go/hpux-core-docs —> HP-UX 11i v3
In the case Oracle “resilvering” is not available, create logical volumes for use as Oracle data
files by using the same options as in the following:
Example for “NOMWC”:
# 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 to OFF; the -c y means that mirror consistency recovery is enabled; the -s g
means that mirroring is PVG-strict—it occurs between different physical volume groups; the -n
system.dbf option lets you specify the name of the logical volume; and the -L 408 option
allocates 408 megabytes.
Example for “MWC”
# lvcreate -m 1 -M y -s g -n system.dbf -L 408 dev/vg_ops
The -M y option ensures that mirror write cache recovery is set ON.
NOTE: Contact Oracle to determine if your version of Oracle RAC allows “resilvering” and to
appropriately configure the mirror consistency recovery policy for your logical volumes.
In the case Oracle “resilvering” is available, 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 n -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 to OFF; the -c n means that mirror consistency recovery is disabled; the -s g
means that mirroring is PVG-strict—it occurs between different physical volume groups; the -n
system.dbf option lets you specify the name of the logical volume; and the -L 408 option
allocates 408 megabytes.
If the command is successful, the system will display messages like the following:
Logical volume “/dev/vg_ops/system.dbf” has been successfully created
with character device “/dev/vg_ops/rsystem.dbf”
Logical volume “/dev/vg_ops/system.dbf” has been successfully extended
Creating a Storage Infrastructure with LVM 45