o2cb(7)                                                         OCFS2 Manual Pages                                                         o2cb(7)

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 clus-
       ter 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 white-
       spaces.

       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  recom-
       mended, 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 con-
              vert 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

SEE ALSO

       mkfs.ocfs2(8) fsck.ocfs2(8) tunefs.ocfs2(8) debugfs.ocfs2(8) ocfs2console(8)

AUTHORS

       Oracle Corporation

COPYRIGHT

       Copyright (C) 2004, 2010 Oracle. All rights reserved.

Version 1.6.4                                                     September 2010                                                           o2cb(7)