Provided by: corosync_2.4.3-0ubuntu1.3_amd64 
NAME
corosync.conf - corosync executive configuration file
SYNOPSIS
/etc/corosync/corosync.conf
DESCRIPTION
The corosync.conf instructs the corosync executive about various parameters needed to
control the corosync executive. Empty lines and lines starting with # character are
ignored. The configuration file consists of bracketed top level directives. The possible
directive choices are:
totem { }
This top level directive contains configuration options for the totem protocol.
logging { }
This top level directive contains configuration options for logging.
quorum { }
This top level directive contains configuration options for quorum.
nodelist { }
This top level directive contains configuration options for nodes in cluster.
qb { } This top level directive contains configuration options related to libqb.
resources { }
This top level directive contains configuration options for resources.
Within the totem directive, an interface directive is required. There is also one
configuration option which is required:
Within the interface sub-directive of totem there are four parameters which are required.
There is one parameter which is optional.
ringnumber
This specifies the ring number for the interface. When using the redundant ring
protocol, each interface should specify separate ring numbers to uniquely identify
to the membership protocol which interface to use for which redundant ring. The
ringnumber must start at 0.
bindnetaddr
This specifies the network address the corosync executive should bind to.
bindnetaddr should be an IP address configured on the system, or a network address.
For example, if the local interface is 192.168.5.92 with netmask 255.255.255.0, you
should set bindnetaddr to 192.168.5.92 or 192.168.5.0. If the local interface is
192.168.5.92 with netmask 255.255.255.192, set bindnetaddr to 192.168.5.92 or
192.168.5.64, and so forth.
This may also be an IPV6 address, in which case IPV6 networking will be used. In
this case, the exact address must be specified and there is no automatic selection
of the network interface within a specific subnet as with IPv4.
If IPv6 networking is used, the nodeid field in nodelist must be specified.
broadcast
This is optional and can be set to yes. If it is set to yes, the broadcast address
will be used for communication. If this option is set, mcastaddr should not be
set.
mcastaddr
This is the multicast address used by corosync executive. The default should work
for most networks, but the network administrator should be queried about a
multicast address to use. Avoid 224.x.x.x because this is a "config" multicast
address.
This may also be an IPV6 multicast address, in which case IPV6 networking will be
used. If IPv6 networking is used, the nodeid field in nodelist must be specified.
It's not needed to use this option if cluster_name option is used. If both options
are used, mcastaddr has higher priority.
mcastport
This specifies the UDP port number. It is possible to use the same multicast
address on a network with the corosync services configured for different UDP ports.
Please note corosync uses two UDP ports mcastport (for mcast receives) and
mcastport - 1 (for mcast sends). If you have multiple clusters on the same network
using the same mcastaddr please configure the mcastports with a gap.
ttl This specifies the Time To Live (TTL). If you run your cluster on a routed network
then the default of "1" will be too small. This option provides a way to increase
this up to 255. The valid range is 0..255. Note that this is only valid on
multicast transport types.
Within the totem directive, there are seven configuration options of which one is
required, five are optional, and one is required when IPV6 is configured in the interface
subdirective. The required directive controls the version of the totem configuration.
The optional option unless using IPV6 directive controls identification of the processor.
The optional options control secrecy and authentication, the redundant ring mode of
operation and maximum network MTU field.
version
This specifies the version of the configuration file. Currently the only valid
version for this directive is 2.
clear_node_high_bit This configuration option is optional and is only relevant when no
nodeid is specified. Some corosync clients require a signed 32 bit nodeid that is greater
than zero however by default corosync uses all 32 bits of the IPv4 address space when
generating a nodeid. Set this option to yes to force the high bit to be zero and therefor
ensure the nodeid is a positive signed 32 bit integer.
WARNING: The clusters behavior is undefined if this option is enabled on only a subset of
the cluster (for example during a rolling upgrade).
crypto_hash
This specifies which HMAC authentication should be used to authenticate all
messages. Valid values are none (no authentication), md5, sha1, sha256, sha384 and
sha512.
The default is sha1.
crypto_cipher
This specifies which cipher should be used to encrypt all messages. Valid values
are none (no encryption), aes256, aes192, aes128 and 3des. Enabling crypto_cipher,
requires also enabling of crypto_hash.
The default is aes256.
secauth
This specifies that HMAC/SHA1 authentication should be used to authenticate all
messages. It further specifies that all data should be encrypted with the nss
library and aes256 encryption algorithm to protect data from eavesdropping.
Enabling this option adds a encryption header to every message sent by totem which
reduces total throughput. Also encryption and authentication consume extra CPU
cycles in corosync.
The default is on.
WARNING: This parameter is deprecated. It's recomended to use combination of
crypto_cipher and crypto_hash.
rrp_mode
This specifies the mode of redundant ring, which may be none, active, or passive.
Currently only 'passive' is supported or tested (using 'active' is not
recommended). Active replication offers slightly lower latency from transmit to
delivery in faulty network environments but with less performance. Passive
replication may nearly double the speed of the totem protocol if the protocol
doesn't become cpu bound. The final option is none, in which case only one network
interface will be used to operate the totem protocol.
If only one interface directive is specified, none is automatically chosen. If
multiple interface directives are specified, only active or passive may be chosen.
The maximum number of interface directives that is allowed for either modes (active
or passive) is 2.
When using multiple interfaces, make sure to use different multicast address/port
(port for same address must differ by at least two) pair for each interface (this
is checked by parser) to make rrp works.
netmtu This specifies the network maximum transmit unit. To set this value beyond 1500,
the regular frame MTU, requires ethernet devices that support large, or also called
jumbo, frames. If any device in the network doesn't support large frames, the
protocol will not operate properly. The hosts must also have their mtu size set
from 1500 to whatever frame size is specified here.
Please note while some NICs or switches claim large frame support, they support
9000 MTU as the maximum frame size including the IP header. Setting the netmtu and
host MTUs to 9000 will cause totem to use the full 9000 bytes of the frame. Then
Linux will add a 18 byte header moving the full frame size to 9018. As a result
some hardware will not operate properly with this size of data. A netmtu of 8982
seems to work for the few large frame devices that have been tested. Some
manufacturers claim large frame support when in fact they support frame sizes of
4500 bytes.
When sending multicast traffic, if the network frequently reconfigures, chances are
that some device in the network doesn't support large frames.
Choose hardware carefully if intending to use large frame support.
The default is 1500.
transport
This directive controls the transport mechanism used. If the interface to which
corosync is binding is an RDMA interface such as RoCEE or Infiniband, the "iba"
parameter may be specified. To avoid the use of multicast entirely, a unicast
transport parameter "udpu" can be specified. This requires specifying the list of
members in nodelist directive, that could potentially make up the membership before
deployment.
The default is udp. The transport type can also be set to udpu or iba.
cluster_name
This specifies the name of cluster and it's used for automatic generating of
multicast address.
config_version
This specifies version of config file. This is converted to unsigned 64-bit int.
By default it's 0. Option is used to prevent joining old nodes with not up-to-date
configuration. If value is not 0, and node is going for first time (only for first
time, join after split doesn't follow this rules) from single-node membership to
multiple nodes membership, other nodes config_versions are collected. If current
node config_version is not equal to highest of collected versions, corosync is
terminated.
ip_version
Specifies version of IP to use for communication. Value can be one of ipv4 or ipv6.
Default (if unspecified) is ipv4.
Within the totem directive, there are several configuration options which are used
to control the operation of the protocol. It is generally not recommended to
change any of these values without proper guidance and sufficient testing. Some
networks may require larger values if suffering from frequent reconfigurations.
Some applications may require faster failure detection times which can be achieved
by reducing the token timeout.
token This timeout is used directly or as a base for real token timeout calculation
(explained in token_coefficient section). Token timeout specifies in milliseconds
until a token loss is declared after not receiving a token. This is the time spent
detecting a failure of a processor in the current configuration. Reforming a new
configuration takes about 50 milliseconds in addition to this timeout.
For real token timeout used by totem it's possible to read cmap value of
runtime.config.token key.
The default is 1000 milliseconds.
token_coefficient
This value is used only when nodelist section is specified and contains at least 3
nodes. If so, real token timeout is then computed as token + (number_of_nodes - 2)
* token_coefficient. This allows cluster to scale without manually changing token
timeout every time new node is added. This value can be set to 0 resulting in
effective removal of this feature.
The default is 650 milliseconds.
token_retransmit
This timeout specifies in milliseconds after how long before receiving a token the
token is retransmitted. This will be automatically calculated if token is
modified. It is not recommended to alter this value without guidance from the
corosync community.
The default is 238 milliseconds.
hold This timeout specifies in milliseconds how long the token should be held by the
representative when the protocol is under low utilization. It is not recommended
to alter this value without guidance from the corosync community.
The default is 180 milliseconds.
token_retransmits_before_loss_const
This value identifies how many token retransmits should be attempted before forming
a new configuration. If this value is set, retransmit and hold will be
automatically calculated from retransmits_before_loss and token.
The default is 4 retransmissions.
join This timeout specifies in milliseconds how long to wait for join messages in the
membership protocol.
The default is 50 milliseconds.
send_join
This timeout specifies in milliseconds an upper range between 0 and send_join to
wait before sending a join message. For configurations with less than 32 nodes,
this parameter is not necessary. For larger rings, this parameter is necessary to
ensure the NIC is not overflowed with join messages on formation of a new ring. A
reasonable value for large rings (128 nodes) would be 80msec. Other timer values
must also change if this value is changed. Seek advice from the corosync mailing
list if trying to run larger configurations.
The default is 0 milliseconds.
consensus
This timeout specifies in milliseconds how long to wait for consensus to be
achieved before starting a new round of membership configuration. The minimum
value for consensus must be 1.2 * token. This value will be automatically
calculated at 1.2 * token if the user doesn't specify a consensus value.
For two node clusters, a consensus larger than the join timeout but less than token
is safe. For three node or larger clusters, consensus should be larger than token.
There is an increasing risk of odd membership changes, which still guarantee
virtual synchrony, as node count grows if consensus is less than token.
The default is 1200 milliseconds.
merge This timeout specifies in milliseconds how long to wait before checking for a
partition when no multicast traffic is being sent. If multicast traffic is being
sent, the merge detection happens automatically as a function of the protocol.
The default is 200 milliseconds.
downcheck
This timeout specifies in milliseconds how long to wait before checking that a
network interface is back up after it has been downed.
The default is 1000 milliseconds.
fail_recv_const
This constant specifies how many rotations of the token without receiving any of
the messages when messages should be received may occur before a new configuration
is formed.
The default is 2500 failures to receive a message.
seqno_unchanged_const
This constant specifies how many rotations of the token without any multicast
traffic should occur before the hold timer is started.
The default is 30 rotations.
heartbeat_failures_allowed
[HeartBeating mechanism] Configures the optional HeartBeating mechanism for faster
failure detection. Keep in mind that engaging this mechanism in lossy networks
could cause faulty loss declaration as the mechanism relies on the network for
heartbeating.
So as a rule of thumb use this mechanism if you require improved failure in low to
medium utilized networks.
This constant specifies the number of heartbeat failures the system should tolerate
before declaring heartbeat failure e.g 3. Also if this value is not set or is 0
then the heartbeat mechanism is not engaged in the system and token rotation is the
method of failure detection
The default is 0 (disabled).
max_network_delay
[HeartBeating mechanism] This constant specifies in milliseconds the approximate
delay that your network takes to transport one packet from one machine to another.
This value is to be set by system engineers and please don't change if not sure as
this effects the failure detection mechanism using heartbeat.
The default is 50 milliseconds.
window_size
This constant specifies the maximum number of messages that may be sent on one
token rotation. If all processors perform equally well, this value could be large
(300), which would introduce higher latency from origination to delivery for very
large rings. To reduce latency in large rings(16+), the defaults are a safe
compromise. If 1 or more slow processor(s) are present among fast processors,
window_size should be no larger than 256000 / netmtu to avoid overflow of the
kernel receive buffers. The user is notified of this by the display of a
retransmit list in the notification logs. There is no loss of data, but
performance is reduced when these errors occur.
The default is 50 messages.
max_messages
This constant specifies the maximum number of messages that may be sent by one
processor on receipt of the token. The max_messages parameter is limited to 256000
/ netmtu to prevent overflow of the kernel transmit buffers.
The default is 17 messages.
miss_count_const
This constant defines the maximum number of times on receipt of a token a message
is checked for retransmission before a retransmission occurs. This parameter is
useful to modify for switches that delay multicast packets compared to unicast
packets. The default setting works well for nearly all modern switches.
The default is 5 messages.
rrp_problem_count_timeout
This specifies the time in milliseconds to wait before decrementing the problem
count by 1 for a particular ring to ensure a link is not marked faulty for
transient network failures.
The default is 2000 milliseconds.
rrp_problem_count_threshold
This specifies the number of times a problem is detected with a link before setting
the link faulty. Once a link is set faulty, no more data is transmitted upon it.
Also, the problem counter is no longer decremented when the problem count timeout
expires.
A problem is detected whenever all tokens from the proceeding processor have not
been received within the rrp_token_expired_timeout. The
rrp_problem_count_threshold * rrp_token_expired_timeout should be atleast 50
milliseconds less then the token timeout, or a complete reconfiguration may occur.
The default is 10 problem counts.
rrp_problem_count_mcast_threshold
This specifies the number of times a problem is detected with multicast before
setting the link faulty for passive rrp mode. This variable is unused in active rrp
mode.
The default is 10 times rrp_problem_count_threshold.
rrp_token_expired_timeout
This specifies the time in milliseconds to increment the problem counter for the
redundant ring protocol after not having received a token from all rings for a
particular processor.
This value will automatically be calculated from the token timeout and
problem_count_threshold but may be overridden. It is not recommended to override
this value without guidance from the corosync community.
The default is 47 milliseconds.
rrp_autorecovery_check_timeout
This specifies the time in milliseconds to check if the failed ring can be auto-
recovered.
The default is 1000 milliseconds.
Within the logging directive, there are several configuration options which are all
optional.
The following 3 options are valid only for the top level logging directive:
timestamp
This specifies that a timestamp is placed on all log messages.
The default is off.
fileline
This specifies that file and line should be printed.
The default is off.
function_name
This specifies that the code function name should be printed.
The default is off.
The following options are valid both for top level logging directive and they can be
overridden in logger_subsys entries.
to_stderr
to_logfile
to_syslog
These specify the destination of logging output. Any combination of these options
may be specified. Valid options are yes and no.
The default is syslog and stderr.
Please note, if you are using to_logfile and want to rotate the file, use
logrotate(8) with the option copytruncate. eg.
/var/log/corosync.log {
missingok
compress
notifempty
daily
rotate 7
copytruncate
}
logfile
If the to_logfile directive is set to yes , this option specifies the pathname of
the log file.
No default.
logfile_priority
This specifies the logfile priority for this particular subsystem. Ignored if debug
is on. Possible values are: alert, crit, debug (same as debug = on), emerg, err,
info, notice, warning.
The default is: info.
syslog_facility
This specifies the syslog facility type that will be used for any messages sent to
syslog. options are daemon, local0, local1, local2, local3, local4, local5, local6
& local7.
The default is daemon.
syslog_priority
This specifies the syslog level for this particular subsystem. Ignored if debug is
on. Possible values are: alert, crit, debug (same as debug = on), emerg, err,
info, notice, warning.
The default is: info.
debug This specifies whether debug output is logged for this particular logger. Also can
contain value trace, what is highest level of debug information.
The default is off.
Within the logging directive, logger_subsys directives are optional.
Within the logger_subsys sub-directive, all of the above logging configuration options are
valid and can be used to override the default settings. The subsys entry, described
below, is mandatory to identify the subsystem.
subsys This specifies the subsystem identity (name) for which logging is specified. This
is the name used by a service in the log_init() call. E.g. 'CPG'. This directive is
required.
Within the quorum directive it is possible to specify the quorum algorithm to use with the
provider
directive. At the time of writing only corosync_votequorum is supported. See
votequorum(5) for configuration options.
Within the nodelist directive it is possible to specify specific information about nodes
in cluster. Directive can contain only node sub-directive, which specifies every node that
should be a member of the membership, and where non-default options are needed. Every node
must have at least ring0_addr field filled.
For UDPU, every node that should be a member of the membership must be specified.
Possible options are:
ringX_addr
This specifies IP address of one of the nodes. X is ring number.
nodeid This configuration option is optional when using IPv4 and required when using IPv6.
This is a 32 bit value specifying the node identifier delivered to the cluster
membership service. If this is not specified with IPv4, the node id will be
determined from the 32 bit IP address the system to which the system is bound with
ring identifier of 0. The node identifier value of zero is reserved and should not
be used.
Within the qb directive it is possible to specify options for libqb.
Possible option is:
ipc_type
This specifies type of IPC to use. Can be one of native (default), shm and socket.
Native means one of shm or socket, depending on what is supported by OS. On systems
with support for both, SHM is selected. SHM is generally faster, but need to
allocate ring buffer file in /dev/shm.
Within the resources directive it is possible to specify options for resources.
Possible option is:
watchdog_device
(Valid only if Corosync was compiled with watchdog support.)
Watchdog device to use. The default value is /dev/watchdog. The special value
"off" disables watchdog usage.
In a cluster with properly configured power fencing a watchdog provides no
additional value. On the other hand, slow watchdog communication may incur multi-
second delays in the Corosync main loop, potentially breaking down membership.
IPMI watchdogs are particularly notorious in this regard: read about
kipmid_max_busy_us in IPMI.txt in the Linux kernel documentation.
FILES
/etc/corosync/corosync.conf
The corosync executive configuration file.
SEE ALSO
corosync_overview(8), votequorum(5), corosync-qdevice(8), logrotate(8)