corosync/man/corosync.conf.5

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.TH COROSYNC_CONF 5 2006-03-28 "corosync Man Page" "Corosync Cluster Engine Programmer's Manual"
.SH NAME
corosync.conf - corosync executive configuration file

.SH SYNOPSIS
/etc/corosync.conf

.SH DESCRIPTION
The corosync.conf instructs the corosync executive about various parameters
needed to control the corosync executive.  The configuration file consists of
bracketed top level directives.  The possible directive choices are
.IR "totem  { } , logging { }.
 These directives are described below.

.TP
totem { }
This top level directive contains configuration options for the totem protocol.
.TP
logging { }
This top level directive contains configuration options for logging.
.TP
event { }
This top level directive contains configuration options for the event service.
.TP
aisexec { }
This top level directive contains configuration options for user privilegies.

.PP
.PP
Within the
.B totem
directive, an interface directive is required.  There is also one configuration
option which is required:
.PP
.PP
Within the
.B interface
sub-directive of totem there are four parameters which are required:

.TP
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.

.TP
bindnetaddr
This specifies the address which the corosync executive should bind.
This address should always end in zero.  If the totem traffic should
be routed over 192.168.5.92, set bindnetaddr to 192.168.5.0.

This may also be an IPV6 address, in which case IPV6 networking will be used.
In this case, the full 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 must be specified.

.TP
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 must be specified.

.TP
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.

.PP
.PP
Within the
.B 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, maximum network MTU,
and number of sending threads, and the nodeid field.

.TP
version
This specifies the version of the configuration file.  Currently the only
valid version for this directive is 2.

.PP
.PP
.TP
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.

.TP
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
sober128 encryption algorithm to protect data from eavesdropping.

Enabling this option adds a 36 byte header to every message sent by totem which
reduces total throughput.  Encryption and authentication consume 75% of CPU
cycles in aisexec as measured with gprof when enabled.

For 100mbit networks with 1500 MTU frame transmissions:
A throughput of 9mb/sec is possible with 100% cpu utilization when this
option is enabled on 3ghz cpus.
A throughput of 10mb/sec is possible wth 20% cpu utilization when this
optin is disabled on 3ghz cpus.

For gig-e networks with large frame transmissions:
A throughput of 20mb/sec is possible when this option is enabled on
3ghz cpus.
A throughput of 60mb/sec is possible when this option is disabled on
3ghz cpus.

The default is on.

.TP
rrp_mode
This specifies the mode of redundant ring, which may be none, active, or
passive.  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.

.TP
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.

Increasing the MTU from 1500 to 8982 doubles throughput performance from 30MB/sec
to 60MB/sec as measured with evsbench with 175000 byte messages with the secauth
directive set to off.

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.

.TP
threads
This directive controls how many threads are used to encrypt and send multicast
messages.  If secauth is off, the protocol will never use threaded sending.
If secauth is on, this directive allows systems to be configured to use
multiple threads to encrypt and send multicast messages.

A thread directive of 0 indicates that no threaded send should be used.  This
mode offers best performance for non-SMP systems.

The default is 0.

.TP
vsftype
This directive controls the virtual synchrony filter type used to identify
a primary component.  The preferred choice is YKD dynamic linear voting,
however, for clusters larger then 32 nodes YKD consumes alot of memory.  For
large scale clusters that are created by changing the MAX_PROCESSORS_COUNT
#define in the C code totem.h file, the virtual synchrony filter "none" is
recommended but then AMF and DLCK services (which are currently experimental)
are not safe for use.

The default is ykd.  The vsftype can also be set to none.

Within the
.B 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.

.TP
token
This 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.

The default is 1000 milliseconds.

.TP
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.

.TP
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.

.TP
retransmits_before_loss
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.

.TP
join
This timeout specifies in milliseconds how long to wait for join messages in
the membership protocol.

The default is 100 milliseconds.

.TP
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 then
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.

.TP
consensus
This timeout specifies in milliseconds how long to wait for consensus to be
achieved before starting a new round of membership configuration.

The default is 200 milliseconds.

.TP
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.

.TP
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 millseconds.

.TP
fail_to_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 50 failures to receive a message.

.TP
seqno_unchanged_const
This constant specifies how many rotations of the token without any multicast
traffic should occur before the merge detection timeout is started.

The default is 30 rotations.

.TP
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).

.TP
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 dont change if not sure as this effects the failure detection
mechanism using heartbeat.

The default is 50 milliseconds.

.TP
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 then 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.

.TP
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.

.TP
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 1000 milliseconds.

.TP
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 20 problem counts.

.TP
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.

.PP
Within the
.B logging
directive, there are several configuration options which are all optional.

.PP
The following 3 options are valid only for the top level logging directive:

.TP
timestamp
This specifies that a timestamp is placed on all log messages.

The default is off.

.TP
fileline
This specifies that file and line should be printed.

The default is off.

.TP
function_name
This specifies that the code function name should be printed.

The default is off.

.PP
The following options are valid both for top level logging directive
and they can be overriden in logger_subsys entries.

.TP
to_stderr
.TP
to_logfile
.TP
to_syslog
These specify the destination of logging output. Any combination of
these options may be specified. Valid options are
.B yes
and
.B no.

The default is syslog and stderr.

.TP
logfile
If the
.B to_logfile
directive is set to
.B yes
, this option specifies the pathname of the log file.

No default.

.TP
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.

.TP
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.

.TP
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.

.TP
debug
This specifies whether debug output is logged for this particular logger.

The default is off.

.TP
tags
This specifies which tags should be traced for this particular logger.
Set debug directive to
.B on
in order to enable tracing using tags.
Values are specified using a vertical bar as a logical OR separator:

enter|leave|trace1|trace2|trace3|...

The default is none.

.PP
Within the
.B logging
directive, logger_subsys directives are optional.

.PP
Within the
.B 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.

.TP
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. 'CKPT'. This directive is
required.

.PP
Within the
.B aisexec
directive, there are two configuration options which are all optional:
.TP
user
.TP
group
These specify the user and group, which is able to run and use corosync.
In any case, this is able to do root:root. But if you don't want run
corosync as root, you can use this directives.

The default is ais.

.SH "FILES"
.TP
/etc/corosync.conf
The corosync executive configuration file.

.SH "SEE ALSO"
.BR corosync_overview (8)
.PP