| HAST.CONF(5) | MidnightBSD File Formats Manual | HAST.CONF(5) |
hast.conf —
configuration file for the
hastd(8) daemon and the
hastctl(8)
utility
The hast.conf file is used by both
hastd(8) daemon and
hastctl(8) control
utility. Configuration file is designed in a way that exactly the same file
can be (and should be) used on both HAST nodes. Every line starting with #
is treated as comment and ignored.
General syntax of the hast.conf file is
following:
# Global section
control <addr>
listen <addr>
replication <mode>
checksum <algorithm>
compression <algorithm>
timeout <seconds>
exec <path>
metaflush on | off
pidfile <path>
on <node> {
# Node section
control <addr>
listen <addr>
pidfile <path>
}
on <node> {
# Node section
control <addr>
listen <addr>
pidfile <path>
}
resource <name> {
# Resource section
replication <mode>
checksum <algorithm>
compression <algorithm>
name <name>
local <path>
timeout <seconds>
exec <path>
metaflush on | off
on <node> {
# Resource-node section
name <name>
# Required
local <path>
metaflush on | off
# Required
remote <addr>
source <addr>
}
on <node> {
# Resource-node section
name <name>
# Required
local <path>
metaflush on | off
# Required
remote <addr>
source <addr>
}
}
Most of the various available configuration parameters are
optional. If parameter is not defined in the particular section, it will be
inherited from the parent section. For example, if the
listen parameter is not defined in the node section,
it will be inherited from the global section. In case the global section
does not define the listen parameter at all, the
default value will be used.
The ⟨node⟩ argument can be replaced either by a full hostname as obtained by gethostname(3), only first part of the hostname, by node's UUID as found in the kern.hostuuid sysctl(8) variable or by node's hostid as found in the kern.hostid sysctl(8) variable.
The following statements are available:
control
⟨addr⟩Address for communication with hastctl(8). Each of the following examples defines the same control address:
uds:///var/run/hastctl unix:///var/run/hastctl /var/run/hastctl
The default value is uds:///var/run/hastctl.
pidfile
⟨path⟩File in which to store the process ID of the main hastd(8) process.
The default value is /var/run/hastd.pid.
listen
⟨addr⟩Address to listen on in form of:
protocol://protocol-specific-address
Each of the following examples defines the same listen address:
0.0.0.0 0.0.0.0:8457 tcp://0.0.0.0 tcp://0.0.0.0:8457 tcp4://0.0.0.0 tcp4://0.0.0.0:8457
Multiple listen addresses can be specified. By default
hastd listens on
tcp4://0.0.0.0:8457 and
tcp6://[::]:8457 if kernel supports IPv4 and
IPv6 respectively.
replication
⟨mode⟩Replication mode should be one of the following:
memsyncReport the write operation as completed when local write
completes and when the remote node acknowledges the data receipt,
but before it actually stores the data. The data on remote node will
be stored directly after sending acknowledgement. This mode is
intended to reduce latency, but still provides a very good
reliability. The only situation where some small amount of data
could be lost is when the data is stored on primary node and sent to
the secondary. Secondary node then acknowledges data receipt and
primary reports success to an application. However, it may happen
that the secondary goes down before the received data is really
stored locally. Before secondary node returns, primary node dies
entirely. When the secondary node comes back to life it becomes the
new primary. Unfortunately some small amount of data which was
confirmed to be stored to the application was lost. The risk of such
a situation is very small. The memsync
replication mode is the default.
fullsyncMark the write operation as completed when local as well as remote write completes. This is the safest and the slowest replication mode.
asyncThe write operation is reported as complete right after the local write completes. This is the fastest and the most dangerous replication mode. This mode should be used when replicating to a distant node where latency is too high for other modes.
checksum
⟨algorithm⟩Checksum algorithm should be one of the following:
compression
⟨algorithm⟩Compression algorithm should be one of the following:
noneholelzftimeout
⟨seconds⟩Connection timeout in seconds. The default value is 20.
exec
⟨path⟩Execute the given program on various HAST events. Below is the list of currently implemented events and arguments the given program is executed with:
<path>
role <resource> <oldrole> <newrole>Executed on both primary and secondary nodes when resource role is changed.
<path>
connect <resource>Executed on both primary and secondary nodes when connection for the given resource between the nodes is established.
<path>
disconnect <resource>Executed on both primary and secondary nodes when connection for the given resource between the nodes is lost.
<path>
syncstart <resource>Executed on primary node when synchronization process of secondary node is started.
<path>
syncdone <resource>Executed on primary node when synchronization process of secondary node is completed successfully.
<path>
syncintr <resource>Executed on primary node when synchronization process of secondary node is interrupted, most likely due to secondary node outage or connection failure between the nodes.
<path>
split-brain <resource>Executed on both primary and secondary nodes when split-brain condition is detected.
The ⟨path⟩ argument should contain full path to
executable program. If the given program exits with code different than
0, hastd will log it as an
error.
The ⟨resource⟩ argument is resource name from the configuration file.
The ⟨oldrole⟩ argument is previous resource role (before the change). It can be one of: init, secondary, primary.
The ⟨newrole⟩ argument is current resource role (after the change). It can be one of: init, secondary, primary.
metaflush
on |
offWhen set to on, flush write cache of the
local provider after every metadata (activemap) update. Flushing write
cache ensures that provider will not reorder writes and that metadata
will be properly updated before real data is stored. If the local
provider does not support flushing write cache (it returns
EOPNOTSUPP on the
BIO_FLUSH request),
hastd will disable
metaflush automatically. The default value is
on.
name
⟨name⟩GEOM provider name that will appear as /dev/hast/<name>. If name is not defined, resource name will be used as provider name.
local
⟨path⟩Path to the local component which will be used as backend provider for the resource. This can be either GEOM provider or regular file.
remote
⟨addr⟩Address of the remote hastd daemon.
Format is the same as for the listen statement.
When operating as a primary node this address will be used to connect to
the secondary node. When operating as a secondary node only connections
from this address will be accepted.
A special value of none can be used when the remote address is not yet known (eg. the other node is not set up yet).
source
⟨addr⟩Local address to bind to before connecting to the remote
hastd daemon. Format is the same as for the
listen statement.
The example configuration file can look as follows:
listen tcp://0.0.0.0
on hasta {
listen tcp://2001:db8::1/64
}
on hastb {
listen tcp://2001:db8::2/64
}
resource shared {
local /dev/da0
on hasta {
remote tcp://10.0.0.2
}
on hastb {
remote tcp://10.0.0.1
}
}
resource tank {
on hasta {
local /dev/mirror/tanka
source tcp://10.0.0.1
remote tcp://10.0.0.2
}
on hastb {
local /dev/mirror/tankb
source tcp://10.0.0.2
remote tcp://10.0.0.1
}
}
The hast.conf was written by
Pawel Jakub Dawidek
<pjd@FreeBSD.org>
under sponsorship of the FreeBSD Foundation.
| January 25, 2012 | midnightbsd-3.1 |