ExpressCluster X 2.0 for Windows Reference Guide - Nec

Chapter 9 Details on network partition resolution resources
Understanding network partition resolution by COM
method and DISK method
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A network partition is solved by combining COM network partition resolution resources and
DISK network partition resolution resources.
When the COM channel (such as a COM port and serial cross cable) is working properly, this
method works in the same way as the COM method. When an error occurs on the COM channel,
this method switches to the shared disk method. This mechanism allows for higher availability
than using only the COM method. The method also resolves achieves network partition faster
than using the disk method alone.
Understanding network partition resolution by PING
method and DISK method
A network partition is solved by combining PING network partition resolution resources and
DISK network partition resolution resources.
When communication with ping device is working properly, this method works in the same way
as the PING method. This mechanism allows for higher availability than using the PING method
alone. The method also solves network partition faster than using only the disk method.
This method works as PING + DISK method when the server which uses PING network partition
resolution resources and the server which uses DISK network partition resolution resources are
identical. For example, in the clusters of hybrid disk configuration, when DISK network partition
resolution resources used by a particular server group and PING network resolution resources
used by the whole clusters are configured, these resources work independently. In such a case, to
configure the resources to work in PING+DISK method, it is required to add PING network
resolution resources to be used only by the same server group as DISK network partition
resolution resources.
Not resolving network partition
• This method can be selected in a cluster that does not use a shared disk.
• If a failure occurs on all network channels between servers in a cluster, all servers failover.
ExpressCluster X 2.0 for Windows Reference Guide