High Availability for Oracle ASM using HP Serviceguard Solutions, September 2010

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Further, the default retry behavior of LVM could result in an I/O operation on an LVM LV taking an
indefinitely long period of time. This behavior could impede ASM retry and rebalance capabilities;
hence a finite timeout must be configured for each LVM LV.
For example, the timeout could be configured to the value (total number of physical paths to the
PV * PV timeout), providing enough time for LVM to try all available paths, if needed.
The PVs used in an ASM disk group can be organized into LVM volume groups as desired by the
customer. In the example shown in Figure 2, for each ASM disk group, the PVs corresponding to its
members are organized into a separate LVM volume group.
The LVM volume groups are marked as exclusive volume groups and exported across the
Serviceguard cluster using standard Serviceguard procedures. As noted above, multiple physical
paths to each physical volume should be configured using the LVM PV Links feature or a separate
multipathing product such as HP StorageWorks Secure Path.
Figure 2: 1-1 mapping between LVM logical and physical volumes for ASM configuration
Sample command sequence for configuring LVM volume groups
In this section, we provide an example of a command sequence that can be used to prepare LVM
Logical Volumes for use by ASM to meet the requirements specified above. The scenario for the
example is that we are preparing a new volume group named vgora_asm with two PVs, each with
two physical paths. The physical paths for the first PV are /dev/dsk/c9t0d1 and /dev/dsk/c10t0d1
and those for the second PV are /dev/dsk/c9t0d2 and /dev/dsk/c10t0d2.
• Create the volume group with the two PVs, incorporating the two physical paths for each (choosing
hh to be the next hexadecimal number that is available on the system, after the volume groups that
are already configured).
# pvcreate -f /dev/rdsk/c9t0d1
# pvcreate -f /dev/rdsk/c9t0d2
# mkdir /dev/vgora_asm
# mknod /dev/vgora_asm/group c 64 0xhh0000
# vgcreate /dev/vgora_asm /dev/dsk/c9t0d1
# vgextend /dev/vgora_asm /dev/dsk/c9t0d2
# vgextend /dev/vgora_asm /dev/dsk/c10t0d1
# vgextend /dev/vgora_asm /dev/dsk/c10t0d2
Disk group
members
ASM disk groups
LVM volume groups
Logical volumes
Physical volumes
DB Instances
ASM Instances
DGn
VGnVG1