Creating a Storage Infrastructure with CVM

Initializing the VERITAS Volume Manager

If you are about to create disk groups for the first time, you need to initialize the Volume Manager. This is done by creating a disk group known as rootdg that contains at least one disk. Use the following command after installing VxVM/CVM on each node:

# vxinstall

This displays a menu-driven program that steps you through the VxVM/CVM initialization sequence. From the main menu, choose the “Custom” option, and specify the disk you wish to include in rootdg.

	IMPORTANT: The rootdg in the VERITAS Volume Manager is not the same as the HP-UX root disk if an LVM volume group is used for the HP-UX root file system (/). Note also that rootdg cannot be used for shared storage. However, rootdg can be used for other local filesystems (e.g., /export/home), so it need not be wasted. Note that you should create a root disk group only once on each node.

Preparing the Cluster for Use with CVM

In order to use the VERITAS Cluster Volume Manager (CVM), you need a cluster that is running with a special CVM package, called a System Multi-node Package (SMP). This means that the cluster must already be configured and running before you create disk groups.

You cannot configure SMP packages through Serviceguard Manager. Once the SMP is configured, however, you can modify its cluster’s configuration if you have root login on one of the cluster nodes. You can view the SMP packages if you have monitor access role. You can halt or start the SMP packages in Serviceguard Manager if you have full-admin access role.

	NOTE: Cluster configuration is described in the previous section.

To prepare the cluster for CVM disk group configuration, you need to set MAX_CONFIGURED_PACKAGES to 1 or greater in the cluster ASCII configuration file, and ensure that only one heartbeat subnet is configured. Then use the following command, which creates the special package that communicates cluster information to CVM:

# cmapplyconf -P /etc/cmcluster/cvm/VxVM-CVM-pkg.conf

	WARNING! The VxVM-CVM-pkg.conf file should never be edited.

After this command completes successfully, you can create disk groups for shared use as described in the following sections. The cluster is now running with a special system multi-node package named VxVM-CVM-pkg, which is on all nodes. This package is shown in the following output of the cmviewcl command:

CLUSTER      STATUS       
example      up           
 
NODE         STATUS       STATE        
ftsys7       up           running
ftsys8       up           running
ftsys9       up           running 
ftsys10      up           running 
 
SYSTEM_MULTI_NODE_PACKAGES:
 
PACKAGE      STATUS       STATE        
VxVM-CVM-pkg up           running

Starting the Cluster and Identifying the Master Node

If it is not already running, start the cluster, which will activate the special CVM package:

# cmruncl

When CVM starts up, it selects a master node, and this is the node from which you must issue the disk group configuration commands. To determine the master node, issue the following command from each node in the cluster:

# vxdctl -c mode

One node will identify itself as the master. Create disk groups from this node.

Initializing Disks for CVM

You need to initialize the physical disks that will be employed in CVM disk groups. If a physical disk has been previously used with LVM, you should use the pvremove command to delete the LVM header data from all the disks in the volume group (this is not necessary if you have not previously used the disk with LVM).

To initialize a disk for CVM, log on to the master node, then use the vxdiskadm program to initialize multiple disks, or use the vxdisksetup command to initialize one disk at a time, as in the following example:

# /usr/lib/vxvm/bin/vxdisksetup -i c0t3d2

Creating Disk Groups

The following steps should be used to create disk groups.

Creating Volumes

Use the vxassist command to create logical volumes, as in the following example:

# vxassist -g logdata make log_files 1024m

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

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. 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.

Creating File Systems

If your installation uses file systems, create them next. Use the following commands to create a file system for mounting on the logical volume just created:

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, file systems, logical volumes, and mount options in the package control script. The package configuration process is described in detail in Chapter 6.

	NOTE: Unlike LVM volume groups, CVM disk groups are not entered in the cluster ASCII configuration file.