OpenVMS Cluster Systems - OpenVMS Systems - HP
OpenVMS Cluster Systems - OpenVMS Systems - HP
OpenVMS Cluster Systems - OpenVMS Systems - HP
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<strong>Cluster</strong> Storage Devices<br />
6.4 MSCP I/O Load Balancing<br />
6.4.6 Overriding MSCP I/O Load Balancing for Special Purposes<br />
In some configurations, you may want to designate one or more systems in your<br />
cluster as the primary I/O servers and restrict I/O traffic on other systems. You<br />
can accomplish these goals by overriding the default load-capacity ratings used by<br />
the MSCP server. For example, if your cluster consists of two Alpha systems and<br />
one VAX 6000-400 system and you want to reduce the MSCP served I/O traffic<br />
to the VAX, you can assign a low MSCP_LOAD value, such as 50, to the VAX.<br />
Because the two Alpha systems each start with a load-capacity rating of 340 and<br />
the VAX now starts with a load-capacity rating of 50, the MSCP served satellites<br />
will direct most of the I/O traffic to the Alpha systems.<br />
6.5 Managing <strong>Cluster</strong> Disks With the Mount Utility<br />
For locally connected disks to be accessible to other nodes in the cluster, the<br />
MSCP server software must be loaded on the computer to which the disks are<br />
connected (see Section 6.3.1). Further, each disk must be mounted with the<br />
Mount utility, using the appropriate qualifier: /CLUSTER, /SYSTEM, or /GROUP.<br />
Mounting multiple disks can be automated with command procedures; a sample<br />
command procedure, MSCPMOUNT.COM, is provided in the SYS$EXAMPLES<br />
directory on your system.<br />
The Mount utility also provides other qualifiers that determine whether a<br />
disk is automatically rebuilt during a remount operation. Different rebuilding<br />
techniques are recommended for data and system disks.<br />
This section describes how to use the Mount utility for these purposes.<br />
6.5.1 Mounting <strong>Cluster</strong> Disks<br />
To mount disks that are to be shared among all computers, specify the MOUNT<br />
command as shown in the following table.<br />
IF... THEN...<br />
At system startup<br />
The disk is attached to a single system<br />
and is to be made available to all other<br />
nodes in the cluster.<br />
The computer has no disks directly<br />
attached to it.<br />
When the system is running<br />
6–24 <strong>Cluster</strong> Storage Devices<br />
Use MOUNT/CLUSTER device-name on the computer to<br />
which the disk is to be mounted. The disk is mounted<br />
on every computer that is active in the cluster at the<br />
time the command executes. First, the disk is mounted<br />
locally. Then, if the mount operation succeeds, the disk is<br />
mounted on other nodes in the cluster.<br />
Use MOUNT/SYSTEM device-name on the computer<br />
for each disk the computer needs to access. The disks<br />
can be attached to a single system or shared disks that<br />
are accessed by an HSx controller. Then, if the mount<br />
operation succeeds, the disk is mounted on the computer<br />
joining the cluster.<br />
You want to add a disk. Use MOUNT/CLUSTER device-name on the computer to<br />
which the disk is to be mounted. The disk is mounted<br />
on every computer that is active in the cluster at the<br />
time the command executes. First, the disk is mounted<br />
locally. Then, if the mount operation succeeds, the disk is<br />
mounted on other nodes in the cluster.<br />
To ensure disks are mounted whenever possible, regardless of the sequence that<br />
systems in the cluster boot (or shut down), startup command procedures should
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