corosync/man/openais.conf.5

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.TH OPENAIS_CONF 5 2005-06-08 "openais Man Page" "Openais Programmer's Manual"
.SH NAME
openais.conf - openais executive configuration file

.SH SYNOPSIS
/etc/ais/openais.conf

.SH DESCRIPTION
The openais.conf instructs the openais executive about various parameters
needed to control the openais executive.  The configuration file consists of
bracketed top level directives.  The possible directive choices are
.IR totem { } " and " 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.

.PP
.PP
Within the 
.B totem
directive, there are four configuration options which are all required:
.TP
version
This specifies the version of the configuration file.  Currently the only
valid version for this directive is 1.

.TP
bindnetaddr
This specifies the address which the openais 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.

Multiple bindnetaddr directives may be specified.  When multiple bindnetaddr
directives are specified, the totem redundant ring protocol will use multiple
interfaces to replicate the network traffic.

.TP
mcastaddr
This is the multicast address used by openais 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.

.TP
mcastport
This specifies the UDP port number.  It is possible to use the same multicast
address on a network with the openais services configured for different
UDP ports.

.PP
Within the 
.B totem 
directive, there are four configuration options which are all optional.
These control secrecy & authentication, the redundant ring mode of operation,
and network MTU, and number of sending threads.

.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
redundantring
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 poorer 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.

At this time redundant ring is only partially implemented and not yet available.

The default is none.

.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 frame room.
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.

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 and is independent of this timeout.

.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 openais community.

.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 openais community.

.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.

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

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

.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.

.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.

.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.

.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.

.PP
Within the 
.B logging
directive, there are four configuration options which are all optional:
.TP
logoutput
This specifies the logging output.  The choices are file, which logs to a file,
stderr, which logs to stderr, and syslog which logs to the system log.  It is
possible to have multiple targets by including this directive with different
options multiple times in the top level directive.

.TP
logfile
If the logoutput: file directive is set, this option specifies where the
log file is written to.  

.TP
debug
This specifies whether debug output is logged.  This is generally a bad idea, 
unless there is some specific bug or problem that must be found in the
executive.  Set the value to on to debug, off to turn of debugging.

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

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

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