1o2cb(7) OCFS2 Manual Pages o2cb(7)
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6 o2cb - Default cluster stack for the OCFS2 file system.
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9 o2cb is the default cluster stack for the OCFS2 file system. It
10 includes a node manager (o2nm) to keep track of the nodes in the clus‐
11 ter, a heartbeat agent (o2hb) to detect live nodes, a network agent
12 (o2net) for intra-cluster node communication and a distributed lock
13 manager (o2dlm) to keep track of lock resources. All these components
14 are in-kernel. It also includes an in-memory file system, dlmfs, to
15 allow userspace to access the in-kernel dlm.
16 This cluster stack has two configuration files, namely,
18 /etc/ocfs2/cluster.conf and /etc/sysconfig/o2cb. Whereas the former
19 keeps track of the cluster layout, the latter keeps track of the clus‐
20 ter timeouts. Both files are only read when the cluster is brought
21 online. Values in use by the online cluster can be perused in the
22 /sys/kernel/config/cluster directory structure.
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26 The cluster layout is specified in /etc/ocfs2/cluster.conf. While it is
27 easier to populate and propagate this configuration file using
28 ocfs2console(8), one can also do it by manually as long as care is
29 taken to format the file correctly.
30 While the console utility is intuitive to use, there are few points to
32 keep in mind.
33 1. The node name needs to match the hostname. It does not need to
35 include the domain name. For example, appserver.oracle.com can be
36 appserver.
37 2. The IP address need not be the one associated with that host‐
39 name. As in, any valid IP address on that node can be used. O2CB will
40 not attempt to match the node name (hostname) with the specified IP
41 address.
42 For best performance, use of a private interconnect (lower latency) is
44 recommended.
45 The cluster.conf file is in a stanza format with two types of stanzas,
47 namely, cluster and node. A typical cluster.conf will have one cluster
48 stanza and multiple node stanzas.
49 The cluster stanza has two parameters:
51 node_count
53 Total number of nodes in the cluster
54 name Name of the cluster
56 The node stanza has five parameters:
59 ip_port
61 IP port
62 ip_address
64 IP address
65 number Unique node number from 0-254
67 name Hostname
69 cluster
71 Name of the cluster
72 Users populating cluster.conf manually should follow the format
74 strictly. As in, stanza header should start at the first column and end
75 with a colon, stanza parameters should start after a tab, a blank line
76 should demarcate each stanza and care taken to avoid stray whitespaces.
77 The O2CB cluster timeouts are specified in /etc/sysconfig/o2cb and can
79 be configured using the o2cb init script.
80 These timeouts are used by the O2CB clusterstack to determine whether a
82 node is dead or alive. While the use of default values is recommended,
83 users can experiment with other values if the defaults are causing spu‐
84 rious fencing.
85 The cluster timeouts are:
87 Heartbeat Dead Threshold
89 The Disk Heartbeat timeout is the number of two second itera‐
90 tions before a node is considered dead. The exact formula used
91 to convert the timeout in seconds to the number of iterations is
92 as follows:
93 O2CB_HEARTBEAT_THRESHOLD = (((timeout in seconds) / 2) + 1)
95 For e.g., to specify a 60 sec timeout, set it to 31. For 120
97 secs, set it to 61. The default for this timeout is 60 secs
98 (O2CB_HEARTBEAT_THRESHOLD = 31).
99 Network Idle Timeout
102 The Network Idle timeout specifies the time in milliseconds
103 before a network connection is considered dead. It defaults to
104 30000 ms.
105 Network Keepalive Delay
108 The Network Keepalive specifies the maximum delay in millisec‐
109 onds before a keepalive packet is sent to another node to check
110 whether it is alive or not. If the node is alive, it will
111 respond. Its defaults to 2000 ms.
112 Network Reconnect Delay
115 The Network Reconnect specifies the minimum delay in millisec‐
116 onds between connection attempts. It defaults to 2000 ms.
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119 A sample /etc/ocfs2/cluster.conf.
120 cluster:
122 node_count = 3
123 name = webcluster
124 node:
126 ip_port = 7777
127 ip_address = 192.168.0.107
128 number = 7
129 name = node7
130 cluster = webcluster
131 node:
133 ip_port = 7777
134 ip_address = 192.168.0.106
135 number = 6
136 name = node6
137 cluster = webcluster
138 node:
140 ip_port = 7777
141 ip_address = 192.168.0.110
142 number = 10
143 name = node10
144 cluster = webcluster
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148 mkfs.ocfs2(8) fsck.ocfs2(8) tunefs.ocfs2(8) debugfs.ocfs2(8) ocfs2con‐
149 sole(8)
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153 Oracle Corporation
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157 Copyright © 2004, 2008 Oracle. All rights reserved.
158Version 1.4.3 July 2008 o2cb(7)