Managing Serviceguard Fifteenth Edition, reprinted May 2008

Building an HA Cluster Configuration
Configuring the Cluster
Chapter 5 267
Mirror Detachment Policies with CVM The default CVM disk
mirror detachment policy is global, which means that as soon as one
node cannot see a specific mirror copy (plex), all nodes cannot see it as
well. The alternate policy is local, which means that if one node cannot
see a specific mirror copy, then CVM will deactivate access to the volume
for that node only.
The global policy is recommended, because it ensures all nodes are
accessing the same current data. If you use local, it can cause problems if
one node cannot update one of the mirror copies and the data on that
copy goes stale. If any of the other nodes read from that mirror copy, they
will read stale data. This can be avoided with the global option, because
all nodes will only use the current mirror copy, so they will all read
consistent data.
This policy can be re-set on a disk group basis by using the vxedit
command, as follows:
vxedit set diskdetpolicy=[global|local] <DiskGroupName>
NOTE The specific commands for creating mirrored and multi-path storage
using CVM are described in the HP-UX documentation for the Veritas
Volume Manager, posted at http://docs.hp.com.
Adding Disk Groups to the Package Configuration
After creating units of storage with VxVM commands, you need to
specify the CVM disk groups in each package configuration ASCII file.
Use one DISK_GROUP parameter for each disk group the package will use.
You also need to identify the CVM disk groups, filesystems, logical
volumes, and mount options in the package control script. The package
configuration process is described in detail in Chapter 6.
Using DSAU during Configuration
You can use DSAU to centralize and simplify configuration and
monitoring tasks. See “What are the Distributed Systems
Administration Utilities?” on page 33.