HP Serviceguard Extended Distance Cluster for Linux A.01.01 Release Notes, Third Edition, May 2009

Table 1-2 Failover Sequence (continued)

SiteNode

Site 1N1

Site 2N4

Site 1N2

Site 2N3

In this table, every node is followed by a node from another site. If this order is not

used, then site failures can result in data loss. In the event of a site failure at site S1, if

N1 goes down first followed by N2, it results in a package failure. This failure occurs

because after N1 fails, the package may failover to N2 if the recommended order of

configuration is not specified. When the package fails over to N2 at the same site, it

starts with a partial mirror disk. Starting with a single mirror disk prevents the package

from starting at site S2 if N2 also fails. The package will not start on a node in site S2

because XDC prevents starting a package that has already started once before with a

partial mirror disk.

For this reason, it is also required that if one node of the four nodes is brought down

at a site for maintenance, then one node at the other site must also be brought down.

So if a node in one site fails, the package will fail over to another node in the other site.

IMPORTANT: It is recommended that you maintain an equal number of nodes at both

sites during maintenance. However, this recommendation does not apply to a 2-node

cluster environment.

What Manuals are Available for this Version

For information about configuring Software RAID in your Extended Distance Cluster

setup, see HP Serviceguard Extended Distance Cluster for Linux Deployment Guide available

on the CD. Later versions of these documents will be available at

http://www.docs.hp.com.

You can also see the following documents when using Software RAID:

• Managing HP Serviceguard for Linux Seventh Edition. This manual describes all basic

cluster configuration and administration tasks

• HP Serviceguard for Linux Version A.11.18 Release Notes.

These documents are available on the HP documentation web site at:

http://docs.hp.com/en/ha.html.