Installation guide

members within the domain. The highest-ranking member of the domain will run the service
whenever it is online. This means that if member A has a higher-rank than member B, the service
will migrate to A if it was running on B if A transitions from offline to online.
unordered domain: The default behavior, members of the domain have no order of preference;
any member may run the service. Services will always migrate to members of their failover domain
whenever possible, however, in an unordered domain.
failback: Services on members of an ordered failover domain should fail back to the node that it
was originally running on before the node failed, which is useful for frequently failing nodes to
prevent frequent service shifts between the failing node and the failover node.
Ordering, restriction, and nofailback are flags and may be combined in almost any way (ie,
ordered+restricted, unordered+unrestricted, etc.). These combinations affect both where services start
after initial quorum formation and which cluster members will take over services in the event that the
service has failed.
3.1.1. Behavior Examples
Given a cluster comprised of this set of members: {A, B, C, D, E, F, G}.
O rd ered , rest rict ed f ailo ver d o main {A, B , C}
With nofailback unset: A service 'S' will always run on member 'A' whenever member 'A' is
online and there is a quorum. If all members of {A, B, C} are offline, the service will not run. If
the service is running on 'C' and 'A' transitions online, the service will migrate to 'A'.
With nofailback set: A service 'S' will run on the highest priority cluster member when a
quorum is formed. If all members of {A, B, C} are offline, the service will not run. If the service
is running on 'C' and 'A' transitions online, the service will remain on 'C' unless 'C' fails, at
which point it will fail over to 'A'.
Un o rd ered , rest rict ed f ailo ver d o main {A, B, C}
A service 'S' will only run if there is a quorum and at least one member of {A, B, C} is online.
If another member of the domain transitions online, the service does not relocate.
O rd ered , u n rest rict ed f ailo ver do main {A, B, C }
With nofailback unset: A service 'S' will run whenever there is a quorum. If a member of the
failover domain is online, the service will run on the highest-priority member, otherwise a
member of the cluster will be chosen at random to run the service. That is, the service will
run on 'A' whenever 'A' is online, followed by 'B'.
With nofailback set: A service 'S' will run whenever there is a quorum. If a member of the
failover domain is online at quorum formation, the service will run on the highest-priority
member of the failover domain. That is, if 'B' is online (but 'A' is not), the service will run on
'B'. If, at some later point, 'A' joins the cluster, the service will not relocate to 'A'.
Un o rd ered , u n rest rict ed f ailo ver d o main {A, B , C}
This is also called a "Set of Preferred Members". When one or more members of the failover
domain are online, the service will run on a nonspecific online member of the failover
domain. If another member of the failover domain transitions online, the service does not
relocate.
3.2. Service Policies
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