xenial (7) o2cb.7.gz

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

SEE ALSO

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

AUTHORS

       Oracle Corporation

COPYRIGHT

       Copyright © 2004, 2010 Oracle. All rights reserved.