Ubuntu Manpage: o2cb - Default cluster stack for the OCFS2 file system.

Provided by: ocfs2-tools_1.6.4-3.1_amd64

NAME

       o2cb - Default cluster stack for the OCFS2 file system.

DESCRIPTION

       o2cb  is  the  default cluster stack for the OCFS2 file system. It includes a node manager (o2nm) to keep
       track of the nodes in the cluster, a heartbeat agent (o2hb) to detect live nodes, a network agent (o2net)
       for intra-cluster node communication and a distributed  lock  manager  (o2dlm)  to  keep  track  of  lock
       resources. All these components are in-kernel. It also includes an in-memory file system, dlmfs, to allow
       userspace to access the in-kernel dlm.

       This  cluster stack has two configuration files, namely, /etc/ocfs2/cluster.conf and /etc/sysconfig/o2cb.
       Whereas the former keeps track of the cluster layout, the latter keeps track  of  the  cluster  timeouts.
       Both  files  are only read when the cluster is brought online. Values in use by the online cluster can be
       perused in the /sys/kernel/config/cluster directory structure.

CONFIGURATION

The cluster layout is specified in /etc/ocfs2/cluster.conf. While it is easier to populate and propagate
this configuration file using ocfs2console(8), one can also do it by manually as long as care is taken to
format the file correctly.

While the console utility is intuitive to use, there are few points to keep in mind.

1. The node name needs to match the hostname. It does not need to include the domain name. For
example, appserver.oracle.com can be appserver.

2. The IP address need not be the one associated with that hostname. As in, any valid IP address on
that node can be used. O2CB will not attempt to match the node name (hostname) with the specified IP
address.

For best performance, use of a private interconnect (lower latency) is recommended.

The cluster.conf file is in a stanza format with two types of stanzas, namely, cluster and node. A
typical cluster.conf will have one cluster stanza and multiple node stanzas.

The cluster stanza has two parameters:

node_count
Total number of nodes in the cluster

name Name of the cluster

The node stanza has five parameters:

ip_port
IP port

ip_address
IP address

number Unique node number from 0-254

name Hostname

cluster
Name of the cluster

Users populating cluster.conf manually should follow the format strictly. As in, stanza header should
start at the first column and end with a colon, stanza parameters should start after a tab, a blank line
should demarcate each stanza and care taken to avoid stray whitespaces.

The O2CB cluster timeouts are specified in /etc/sysconfig/o2cb and can be configured using the o2cb init
script.

These timeouts are used by the O2CB clusterstack to determine whether a node is dead or alive. While the
use of default values is recommended, users can experiment with other values if the defaults are causing
spurious fencing.

The cluster timeouts are:

Heartbeat Dead Threshold
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 e.g., 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).

Network Idle Timeout
The Network Idle timeout specifies the time in milliseconds before a network connection is
considered dead. It defaults to 30000 ms.

Network Keepalive Delay
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. If the node is alive, it will respond.
Its defaults to 2000 ms.

Network Reconnect Delay
The Network Reconnect specifies the minimum delay in milliseconds between connection attempts. It
defaults to 2000 ms.

EXAMPLES

       A sample /etc/ocfs2/cluster.conf.

       cluster:
           node_count = 3
           name = webcluster

       node:
           ip_port = 7777
           ip_address = 192.168.0.107
           number = 7
           name = node7
           cluster = webcluster

       node:
           ip_port = 7777
           ip_address = 192.168.0.106
           number = 6
           name = node6
           cluster = webcluster

       node:
           ip_port = 7777
           ip_address = 192.168.0.110
           number = 10
           name = node10
           cluster = webcluster

AUTHORS

       Oracle Corporation

COPYRIGHT