DC_SERVER(1) distcache DC_SERVER(1)NAME
dc_server - Distributed session cache server
SYNOPSIS
dc_server -listen <address> [options]
DESCRIPTION
dc_server runs a cache server and starts listening on a configurable
network address for connections. Incoming connections are expected to
communicate using the distcache(8) protocol, and would typically be
instances of dc_client(1) running on other machines.
OPTIONS-daemon
After initialising, dc_server will detach from the parent process,
close standard file-descriptors, etc. If this flag is not set,
dc_server will run in the foreground. It is recommended to use this
flag in combination with the pidfile flag to simplify stopping and
restarting services.
-user user
This switch will attempt to change user privileges of dc_server to
the given user ID after initialising its listening socket. On most
systems, this can only work if dc_server is started as the root
user. It is important to note that the change of user ID occurs
after the listening socket is create. This ensures that the listen‐
ing socket is created with the most restrictive permissions, and
that the ability to connect to servers at run-time corresponds to
the given user (rather than having unusual root permissions on
startup).
-listen address
Configures the address on which dc_server should listen for incom‐
ing connections. The syntax is that defined by the libnal API.
Some examples follow;
# Listen on port 9001 for all TCP/IPv4 interfaces
dc_server -listen IP:9001
# Listen on port 9001 on a specific TCP/IPv4 interface
dc_server -listen IP:192.168.0.1:9001
dc_server -listen IP:cacheserver.localnet:9001
# Listen on a unix domain socket in the /tmp directory
dc_server -listen UNIX:/tmp/cacheserver
-sockowner user
This switch is only useful when listening (see -listen) on unix
domain sockets. It will attempt to change ownership of the created
socket file.
-sockgroup group
This switch is only useful when listening (see -listen) on unix
domain sockets. It will attempt to change group ownership of the
created socket file.
-sockperms perms
This switch is only useful when listening (see -listen) on unix
domain sockets. It will attempt to change file permissions for the
created socket file, and is specified in the standard octal nota‐
tion used for unix file permissions. Eg. to start dc_server to run
as the nobody user, listening on a unix domain socket that can only
be connected to by the root user or members of the dcclient group;
# dc_server -listen UNIX:/tmp/cacheserver -user nobody \
-sockgroup dcclient -sockperms 440
-sessions num
Specifies a maximum number of sessions that should be stored in the
cache. All sessions in a cache have an expiry time so that they
will, if they have not been forcibly removed before that time, be
expired out of the cache. If it is desirable to allow long session
timeouts under normal situations yet protect against the session
cache growing without limit periods of high-load, this limit can
provide the required balance. If the session cache reaches this
limit, it will automatically rotate out those sessions in the cache
that are due to expire soonest. It is not (yet) possible to have no
limit at all, though a future version should support this by allow‐
ing the user to specify zero.
The default value for this flag is 512.
-progress num
dc_server will, by default, log a line of output to stdout whenever
there is cache activity, but will make sure to do so no more often
than once a second. If -progress is specified, this will take
precedence so that output will be emitted whenever num operations
have occurred since the last output, irrespective of how little
time has elapsed. The once-a-second logic remains behind this, so
that if less than num operations has taken place but at least one
second has passed, output will still be logged. This flag has no
effect if -daemon is used.
-pidfile path
This is a standard flag for many programs, and most useful in com‐
bination with -daemon. When -pidfile is specified dc_server will
write its process ID to a file at the specified path upon success‐
ful initialisation. To use this path file to later kill the running
dc_server instance, use something like (where pidfile.pid is what‐
ever path was);
kill `cat pidfile.pid`
-killable
The default behaviour of dc_server is to silently ignore SIGUSR1
and SIGUSR2 signals, but with this switch enabled it will handle
these signals and close down cleanly (mainly useful for developers
as an alternative to SIGKILL which is less useful for debugging
memory leaks).
-h, -help, -?
Any of these flags will cause dc_server to display a brief usage
summary to the console and exit cleanly. Any other flags are
ignored.
SEE ALSOdc_client(1)
Distributed caching client proxy.
dc_snoop(1)
Distcache protocol analyser and debugging tool.
distcache(8)
Overview of the distcache architecture.
http://www.distcache.org/
Distcache home page.
AUTHOR
This toolkit was designed and implemented by Geoff Thorpe for Crypto‐
graphic Appliances Incorporated. Since the project was released into
open source, it has a home page and a project environment where devel‐
opment, mailing lists, and releases are organised. For problems with
the software or this man page please check for new releases at the
project web-site below, mail the users mailing list described there, or
contact the author at geoff@geoffthorpe.net.
Home Page: http://www.distcache.org
1.4.5 2004.03.23 DC_SERVER(1)