/etc/sysconfig/o2cb - Cluster configuration file for the o2cb
The configuration file /etc/sysconfig/o2cb
stores the active cluster
stack, its name and the various cluster timeouts for the o2cb
This file can be populated using the o2cb
init script. An example of the
same is illustrated in the examples section.
The list of configurable parameters in this file are:
- Name of the cluster stack. The possible values are
o2cb, pcmk and cman. o2cb is the default
cluster stack of the OCFS2 file system. pcmk (Pacemaker) and
cman (rgmanager) are the two other cluster stacks that are
supported by the same file system.
- Name of the active cluster. While /etc/ocfs2/cluster.conf
can hold descriptions of multiple clusters, only one can be active at any
one time. The name of that active cluster is specified here. The name
itself can be upto 16 alphanumeric characters [0-9A-Za-z] with no special
The remaining configurable parameters (cluster timeouts) are only relevant for
cluster stack. These cluster timeouts are used by the
cluster stack to determine whether a node is dead or alive. The
default timeouts are just a guide and may need to be tweaked depending on the
hardware the software is running on.
The various cluster timeouts
for the o2cb
cluster stack are:
- The disk heartbeat timeout is the number of two second
iterations before a node is considered dead. The exact formula used to
convert the timeout in seconds to the number of iterations is as follows:
O2CB_HEARTBEAT_THRESHOLD = (((timeout in seconds) / 2) + 1)
For example, to specify a 60 sec timeout, set it to 31. For 120 secs, set it
to 61. The default for this timeout is 60 secs (O2CB_HEARTBEAT_THRESHOLD =
While it defaults to 60 secs, multipath users typically set it to 120 secs.
- The network idle timeout specifies the time in milliseconds
before a network connection is considered dead. While it defaults to 30000
ms, network bonding users typically set it to 60000 ms.
- The network keepalive specifies the maximum delay in
milliseconds before a keepalive packet is sent to another node to check
whether it is alive or not. It defaults to 2000 ms.
- The network reconnect specifies the minimum delay in
milliseconds between repeated connect attempts. It defaults to 2000
The example below illustrates populating the o2cb sysconfig file using the
$ service o2cb configure
Configuring the O2CB driver.
This will configure the on-boot properties of the O2CB driver.
The following questions will determine whether the driver is loaded on
boot. The current values will be shown in brackets (''). Hitting
<ENTER> without typing an answer will keep that current value. Ctrl-C
Load O2CB driver on boot (y/n) [n]: y
Cluster stack backing O2CB [o2cb]:
Cluster to start on boot (Enter "none" to clear) [ocfs2]: webcluster
Specify heartbeat dead threshold (>=7) : 62
Specify network idle timeout in ms (>=5000) : 60000
Specify network keepalive delay in ms (>=1000) :
Specify network reconnect delay in ms (>=2000) :
Writing O2CB configuration: OK
$ cat /etc/sysconfig/o2cb
# This is a configuration file for automatic startup of the O2CB
# driver. It is generated by running /etc/init.d/o2cb configure.
# On Debian based systems the preferred method is running
# 'dpkg-reconfigure ocfs2-tools'.
# O2CB_ENABLED: 'true' means to load the driver on boot.
# O2CB_STACK: The name of the cluster stack backing O2CB.
# O2CB_BOOTCLUSTER: If not empty, the name of a cluster to start.
# O2CB_HEARTBEAT_THRESHOLD: Iterations before a node is considered dead.
# O2CB_IDLE_TIMEOUT_MS: Time in ms before a network connection is considered dead.
# O2CB_KEEPALIVE_DELAY_MS: Max time in ms before a keepalive packet is sent
# O2CB_RECONNECT_DELAY_MS: Min time in ms between connection attempts
o2cb(7) o2cb(8) ocfs2.cluster.conf(5)
Copyright © 2004, 2012 Oracle. All rights reserved.