The configuration file /etc/sysconfig/o2cb stores the active cluster stack, its name and the various cluster timeouts for the o2cb cluster stack.
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 up to 16 alphanumeric characters [0-9A-Za-z] with no special characters.
The remaining configurable parameters (cluster timeouts) are only relevant for the o2cb cluster stack. These cluster timeouts are used by the o2cb 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 = 31).
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 ms.
The example below illustrates populating the o2cb sysconfig file using the o2cb init script.
$ 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 will abort. 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_ENABLED=true # O2CB_STACK: The name of the cluster stack backing O2CB. O2CB_STACK=o2cb # O2CB_BOOTCLUSTER: If not empty, the name of a cluster to start. O2CB_BOOTCLUSTER=webcluster # O2CB_HEARTBEAT_THRESHOLD: Iterations before a node is considered dead. O2CB_HEARTBEAT_THRESHOLD=62 # O2CB_IDLE_TIMEOUT_MS: Time in ms before a network connection is considered dead. O2CB_IDLE_TIMEOUT_MS=60000 # O2CB_KEEPALIVE_DELAY_MS: Max time in ms before a keepalive packet is sent O2CB_KEEPALIVE_DELAY_MS=2000 # O2CB_RECONNECT_DELAY_MS: Min time in ms between connection attempts O2CB_RECONNECT_DELAY_MS=2000
o2cb(7) o2cb(8) ocfs2.cluster.conf(5)
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o2cb(7), o2cb(8), ocfs2(7), ocfs2.cluster.conf(5), ocfs2_hb_ctl(8).