Novell OPEN ENTERPRISE SERVER CLUSTER SERVICES 1.8.2 - ADMINISTRATION, Руководство пользователя, Страница: 11 / 61

Overview 11
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Web Site A moves to Web Server 2 and Web Site B moves to Web Server 3. IP addresses and
certificates also move to Web Server 2 and Web Server 3.
When you configured the cluster, you decided where the Web sites hosted on each Web server would
go should a failure occur. In the previous example, you configured Web Site A to move to Web
Server 2 and Web Site B to move to Web Server 3. This way, the workload once handled by Web
Server 1 is evenly distributed.
When Web Server 1 failed, Novell Cluster Services software
Š
Detected a failure.
Š
Remounted the shared data directories (that were formerly mounted on Web server 1) on Web
Server 2 and Web Server 3 as specified.
Š Restarted applications (that were running on Web Server 1) on Web Server 2 and Web Server 3
as specified.
Š
Transferred IP addresses to Web Server 2 and Web Server 3 as specified.
In this example, the failover process happened quickly and users regained access to Web site
information within seconds, and in most cases, without having to log in again.
Now suppose the problems with Web Server 1 are resolved, and Web Server 1 is returned to a
normal operating state. Web Site A and Web Site B will automatically fail back, or be moved back to
Web Server 1, and Web Server operation will return back to the way it was before Web Server 1
failed.
Novell Cluster Services also provides resource migration capabilities. You can move applications,
Web sites, etc. to other servers in your cluster without waiting for a server to fail.
For example, you could have manually moved Web Site A or Web Site B from Web Server 1 to
either of the other servers in the cluster. You might want to do this to upgrade or perform scheduled
maintenance on Web Server 1, or just to increase performance or accessibility of the Web sites.
1.3 Cluster Configuration
Typical cluster configurations normally include a shared disk subsystem connected to all servers in
the cluster. The shared disk subsystem can be connected via high-speed fibre channel cards, cables,
and switches, or it can be configured to use shared SCSI or iSCSI. If a server fails, another
designated server in the cluster automatically mounts the shared disk directories previously mounted
on the failed server. This gives network users continuous access to the directories on the shared disk
subsystem.