The purpose of the cluster lock is to ensure that only one
new cluster is formed in the event that exactly half of the previously
clustered nodes try to form a new cluster. It is critical that only
one new cluster is formed and that it alone has access to the disks
specified in its packages. You can specify an LVM lock disk, a lock
LUN, or a quorum server as the cluster lock. For more information
about the cluster lock, and requirements and recommendations, see “Cluster
Lock”.
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 | NOTE: You cannot use more than one type of lock in the same
cluster. |
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A one-node cluster does not require a lock. Two-node clusters
require the use of a cluster lock, and a lock is recommended for
larger clusters as well. Clusters larger than four nodes can use
only a quorum server as the cluster lock. In selecting a cluster
lock configuration, be careful to anticipate any potential need
for additional cluster nodes.
For more information on lock disks, lock LUNs, and the Quorum
Server, see “Choosing
Cluster Lock Disks”, “Setting
Up a Lock LUN”, and “Setting Up and
Running the Quorum Server”.
Cluster
Lock Disk and Re-formation Time |
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cmquerycl displays the failover time for the cluster in the Possible Cluster Lock Devices section, for example:
Possible Cluster Lock Devices:/dev/dsk/c0t1d4 30 secondsNote: all lock disks have the same failover time |
All disks in all volume groups which are accessible by all
nodes in the cluster are potential cluster lock devices, but because
it takes a fixed amount of time to acquire the cluster lock, regardless
of the lock device, only the first potential lock device is displayed.
You may need to choose a different device because of power considerations;
see “Power
Supply Planning ”.
Planning
for Expansion |
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Bear in mind that a cluster with more than 4 nodes cannot
use a lock disk or lock LUN. Thus, if you plan to add enough nodes
to bring the total to more than 4, you should use a quorum server.
Using
a Quorum Server |
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The operation of Quorum Server is described under “Use
of the Quorum Server as the Cluster Lock”. See also “Cluster
Lock”.
A quorum server:
Can be used with up to 150 clusters,
not exceeding 300 nodes total.
Can support a cluster with any supported number
of nodes.
Must be configured on an IPv4, not an IPv6, network.
Can communicate with the cluster on up to two subnets
(a primary and an alternate).
The HP Serviceguard Quorum Server Version A.03.00
Release Notes provide detailed information on installing,
updating, configuring and running the Quorum Server are ed
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 | IMPORTANT: If you plan to use a Quorum Server, make sure you
read the HP Serviceguard Quorum Server Version A.03.00
Release Notes before you proceed. You can find them
at: http://www.docs.hp.com -> High Availability -> Quorum Server. You should also consult the Quorum Server white papers
at the same location. |
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You may find it useful to use the Quorum Server Worksheet that
follows to identify a quorum server for use with one or more clusters.
You may also want to enter quorum server host and timing parameters
on the Cluster Configuration Worksheet. Blank worksheets are in Appendix F “Blank
Planning Worksheets”.
On the QS worksheet, enter the following:
- Quorum Server Host
Enter the host name (and alternate address, if any) for the
quorum server.
- IP Address
Enter the IP v4 address(es) by which the quorum server
will be connected to the cluster.
- Supported Node Names
Enter the name (39 characters or fewer) of each cluster node
that will be supported by this quorum server. These entries will
be entered into qs_authfile on the system that is running the quorum server process.
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Quorum Server Data:
==============================================================================
QS Hostname: __________IP Address: _______________IP Address:_______________
==============================================================================
Quorum Services are Provided for:
Cluster Name: ___________________________________________________________
Host Names ____________________________________________
Host Names ____________________________________________
Cluster Name: ___________________________________________________________
Host Names ____________________________________________
Host Names ____________________________________________
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