OpenVMS Cluster Systems - OpenVMS Systems - HP

Maintaining an OpenVMS Cluster System
10.13 Cluster Performance
Step Action
1 To determine which clusterwide disks may be problem disks:
1. Create a node-by-node summary of disk I/O using the MONITOR/NODE command
2. Adjust the ‘‘row sum’’ column for MSCP served disks as follows:
• I/O rate on serving node includes local requests and all requests from other nodes
• I/O rate on other nodes includes requests generated from that node
• Requests from remote nodes are counted twice in the row sum column
3. Note disks with the row sum more than 8 I/Os per second
4. Eliminate from the list of cluster problem disks the disks that are:
• Not shared
• Dedicated to an application
• In the process of being backed up
2 For each node, determine the impact of potential problem disks:
• If a disporportionate amount of a disk’s I/O comes from a particular node, the problem
is most likely specific to the node.
• If a disk’s I/O is spread evenly over the cluster, the problem may be clusterwide overuse.
• If the average queue length for a disk on a given node is less than 0.2, then the disk is
having little impact on the node.
3 For each problem disk, determine whether:
• Page and swap files from any node are on the disk.
• Commonly used programs or data files are on the disk (use the SHOW DEVICE/FILES
command).
• Users with default directories on the disk are causing the problem.
10.13.3 Using Compaq Availability Manager and DECamds
Compaq Availability Manager and DECamds are real-time monitoring, diagnostic,
and correction tools used by system managers to improve the availability and
throughput of a system. Availability Manager runs on OpenVMS Alpha or on a
Windows node. DECamds runs on both OpenVMS VAX and OpenVMS Alpha and
uses the DECwindows interface.
These products, which are included with the operating system, help system
managers correct system resource utilization problems for CPU usage, low
memory, lock contention, hung or runaway processes, I/O, disks, page files, and
swap files.
Availability Manager enables you to monitor one or more OpenVMS nodes on an
extended LAN from either an OpenVMS Alpha or a Windows node. Availability
Manager collects system and process data from multiple OpenVMS nodes
simultaneously. It analyzes the data and displays the output using a native Java
GUI.
10–22 Maintaining an OpenVMS Cluster System