.TH nmdb 1 "11/Sep/2006"
.SH NAME
nmdb - A TIPC-based database manager
.SH SYNOPSYS
nmdb [-d dbpath] [-l lower] [-L upper] [-c nobj] [-f] [-p] [-h]
.SH DESCRIPTION

nmdb is a TIPC-based database manager.

It allows all the applications in the cluster to store (key, value) pairs in a
central cache and database in a transparent way.

It can also be used as a generic caching system (pretty much like memcached),
because it has a very fast cache that can be used without impacting on the
database.

Before using it, you need to create the backing database. As nmdb uses
.BR qdbm (3)
as a backend, you need to do this using the
.I dpmgr
command. See
.B "INVOCATION EXAMPLE"
below for more important information.

The database is accessed with the
.BR libnmdb (3)
library. Consult its manual page for programming information. Python bindings
are also available.

For additional documentation, go to the project's website at
.IR http://auriga.wearlab.de/~alb/nmdb .

.SH OPTIONS
.TP
.B "-d dbpath"
Indicate the path to the database file to use. It must have been created with
.RB ' "dpmgr create"
.IR "dbpath" '
and have read and write permissions. If a name is not provided, "database"
will be used.
.TP
.B "-l lower"
Lower TIPC port number to bind to. Defaults to 10. It's useful if you want to
run more than one nmdb instance in the same TIPC cluster.
.TP
.B "-L upper"
Upper TIPC port number to bind to. Defaults to the same value
.B lower
is defined. Useful mainly for passive mode (which is not implemented yet).
.TP
.B "-c nobj"
Sets the maximum number of objects the cache will held, in thousands. Note
that the size of the memory used by the cache layer depends on the size of the
object exclusively. It defaults to 128, so the default cache size has space to
hold 128 thousand objects.
.TP
.B "-f"
Stay in the foreground, don't fork. Useful for debugging. The default is to
fork.
.TP
.B "-p"
Enable passive mode, where the server never replies requests, but acts upon
them. It's useful when you want to have a live database mirror, in case the
main node fails. It still requires a manual restart to became active, but at
least you have a recent up-to-date database. Be aware that it's not widely
tested (although it should work fine), and do
.I not
start an active and a passive server in the same machine (it misbehaves under
some circumnstances, and doesn't make much sense anyway).
.TP
.B "-h"
Show a brief help.

.SH INVOCATION EXAMPLE
To create the database:
.B "dpmgr create /var/lib/nmpc-db"

To run the server with the said database:
.B "nmpc -d /var/lib/nmpc-db"

Be
.I very
careful not to start more than one nmdb instance on the same port at the same
time, even if it's on different machines. TIPC allows you to bind the same
port many times (and it's a very good feature), and all of them will get the
messages, which will result in several answers, which will confuse the
clients. This behaviour is different from the normal IP networking, where you
can't bind a port twice.

.SH SEE ALSO
.BR libnmdb (3),
.B TIPC
(http://tipc.sf.net),
.BR qdbm (3).
.SH AUTHORS
Created by Alberto Bertogli (albertito@gmail.com).