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Managing Serviceguard Fifteenth Edition > Chapter 4 Planning
and Documenting an HA Cluster Hardware Planning |
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Hardware planning requires examining the physical hardware itself. One useful procedure is to sketch the hardware configuration in a diagram that shows adapter cards and buses, cabling, disks and peripherals. A sample diagram for a two-node cluster is shown in Figure 4-1 “Sample Cluster Configuration ”.
Create a similar sketch for your own cluster, and record the information on the Hardware Worksheet (see “Hardware Configuration Worksheet ”). Indicate which device adapters occupy which slots, and determine the bus address for each adapter. Update the details as you do the cluster configuration (described in Chapter 5). Use one form for each SPU. The form has three parts:
SPU information includes the basic characteristics of the systems you are using in the cluster. Different models of computers can be mixed in the same cluster. This configuration model also applies to HP Integrity servers. HP-UX workstations are not supported for Serviceguard. On one worksheet per node (see “Hardware Configuration Worksheet ”), include the following items: Serviceguard monitors LAN interfaces.
Serviceguard communication relies on the exchange of DLPI (Data Link Provider Interface) traffic at the data link layer (for nodes on the same subnet) and the UDP/TCP (User Datagram Protocol/Transmission Control Protocol) traffic at the Transport layer between cluster nodes. While a minimum of one LAN interface per subnet is required, at least two LAN interfaces, one primary and one or more standby, are needed to eliminate single points of network failure.
HP recommends that you configure heartbeats on all subnets, including those to be used for client data. Collect the following information for each LAN interface:
This information is used in creating the subnet groupings and identifying the IP addresses used in the cluster and package configuration files. SCSI standards define priority according to SCSI address. To prevent controller starvation on the SPU, the SCSI interface cards must be configured at the highest priorities. Therefore, when configuring a highly available cluster, you should give nodes the highest priority SCSI addresses, and give disks addresses of lesser priority. For SCSI, high priority starts at seven, goes down to zero, and then goes from 15 to eight. Therefore, seven is the highest priority and eight is the lowest priority. For example, if there will be a maximum of four nodes in the cluster, and all four systems will share a string of disks, then the SCSI address must be uniquely set on the interface cards in all four systems, and must be high priority addresses. So the addressing for the systems and disks would be as follows: Table 4-1 SCSI Addressing in Cluster Configuration
Collect the following information for each disk connected to each disk device adapter on the node:
This information is used in creating the mirrored disk configuration using Logical Volume Manager. In addition, it is useful to gather as much information as possible about your disk configuration. You can obtain information about available disks by using the following commands:
These are standard HP-UX commands. See their man pages for complete information about usage. The commands should be issued from all nodes after installing the hardware and rebooting the system. The information will be useful when doing storage group and cluster configuration. You can mark up a printed listing of the output from the lssf command to indicate which physical volume group a disk should be assigned to. The following worksheet will help you organize and record your specific cluster hardware configuration. This worksheet is an example; blank worksheets are in Appendix F “Blank Planning Worksheets”. Make as many copies as you need. SPU Information: |
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