Managing Serviceguard 14th Edition, June 2007
Building an HA Cluster Configuration
Creating the Storage Infrastructure and Filesystems with Veritas Cluster Volume Manager (CVM)
Chapter 5 261
This command creates a 1024 MB volume named log_files in a disk
group named logdata. The volume can be referenced with the block
device file /dev/vx/dsk/logdata/log_files or the raw (character)
device file /dev/vx/rdsk/logdata/log_files.
Verify the configuration with the following command:
vxdg list
If you are using CVM with CFS, use CFS commands to create file
systems on the volumes you have created; see “Creating a Storage
Infrastructure with Veritas Cluster File System (CFS)” on page 245.
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 can ensure 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 tries to read from that mirror
copy, they would read the 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.