What is a Lock disk

[Viney Kumar]

Hi

What is a Lock disk,what is the use of it in cluster.........


Viney

[VK2COT]

Hello,

Some basic details.

a) The cluster lock disk, or a Quorum Server
- which is a very different option, is used
only during cluster reformation and only for
specific situations.

b) A cluster lock disk is required for the
formation of a two-node cluster. Without a
cluster lock disk, the cluster would not be
able to reform if one node fails, causing
the entire cluster to go down.

c) Cluster lock functionality may be
implemented by using LVM disks or using a
Quorum server.

d) With three or four nodes, a cluster lock
is recommended but not required. For three
nodes, there would never be a situation
where the nodes are divided 50/50. However,
if a node is pulled out of the cluster for
maintenance purposes, then the cluster lock
would be used if one of the remaining two
nodes in the cluster fails.

e) For four nodes, the cluster lock disk
would be used when the nodes are separated
into two, 2-node sub clusters. The lock is
not required, because the chance of being
split into two, equally sized halves is very
small for most environments.

f) For five or more nodes, a cluster lock
using LVM disks is not supported. While a
Quorum Server could be used, it would be
optional.

More details are in various ServiceGuard
documents available at http://docs.hp.com.

Cheers,

VK2COT

[Johnson Punniyalingam]

Cluster lock disk

The Cluster lock is a disk located in a volume group shared by all the nodes in the cluster . The cluster lock volume group and the pshyical volumer are identified in the Cluster configuration file,

The cluster lock is used as a tiebraker only for the situation in which the running cluster fails and atempt to refrom the cluster, the cluster is split init two subcluster of equal size , Each sub cluster will attempt to acquire the cluster lock.

the sub cksuter that gets the cluster lock will form the cluster , The subcluster that gets the cluster lock qill form the new cluster , The Sub cluster that does not get the cluster lock will panic in order to allow existing application to failover to

the new cluster which has been formed

Thanks,
Johnson

[sujit kumar singh]

http://forums11.itrc.hp.com/service/forums/helptips.do?#33

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regards

Suujit