Novell LINUX ENTERPRISE 11 - HIGH AVAILABILITY, Руководство пользователя, Страница: 297 / 298

try-restart
and
reload
as well. LSB resource agents are located in
/etc/
init.d
. Find more information about LSB resource agents and the actual speci-
fication at
http://www.linux-ha.org/LSBResourceAgent
and
http://www.linux-foundation.org/spec/refspecs/LSB_3.0
.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html
node
Any computer (real or virtual) that is a member of a cluster and invisible to the
user.
pingd
The ping daemon. It continuously contacts one or more servers outside the cluster
with ICMP pings.
policy engine (PE)
The policy engine computes the actions that need to be taken to implement policy
changes in the CIB. This information is then passed on to the transaction engine,
which in turn implements the policy changes in the cluster setup. The PE always
runs on the DC.
OCF resource agent
OCF resource agents are similar to LSB resource agents (init scripts). Any OCF
resource agent must support
start
,
stop
, and
status
(sometimes called
monitor
) options. Additionally, they support a
metadata
option that returns
the description of the resource agent type in XML. Additional options may be
supported, but are not mandatory. OCF resource agents reside in
/usr/lib/
ocf/resource.d/ provider .
Find more information about OCF resource
agents and a draft of the specification at
http://www.linux-ha.org/
OCFResourceAgent
and
http://www.opencf.org/cgi-bin/viewcvs
.cgi/specs/ra/resource-agent-api.txt?rev=HEAD
.
quorum
In a cluster, a cluster partition is defined to have quorum (is “quorate”) if it has the
majority of nodes (or votes). Quorum distinguishes exactly one partition. It is part
of the algorithm to prevent several disconnected partitions or nodes from proceeding
and causing data and service corruption (split brain). Quorum is a prerequisite for
fencing, which then ensures that quorum is indeed unique.
Terminology 287