10.2;glbd (Global Location Broker Daemon), NCK version 1.5.1, 89/05/31
glbd - Global Location Broker Daemon
usage: /etc/ncs/glbd [ -create { -first [ -family family_name ] | -from host_name } ]
[ -change_family family_name ] [ -listen family_list ] [ -version ]
DESCRIPTION
The Global Location Broker (GLB), part of the Network Computing System
(NCS), helps clients to locate servers on a network or internet. The GLB
database stores the locations (that is, the network addresses and port
numbers) where server processes are running. A daemon maintains this
database and provides access to it.
There are two versions of the GLB daemon: glbd and nrglbd. We provide
the replicatable version, glbd, only for Apollo, SunOS, and ULTRIX
systems. For other systems, we provide the non-replicatable version,
nrglbd.
Here, we describe only glbd.
You can replicate the GLB database to increase its availability. Copies
of the database can exist on several hosts, with a glbd running on each
of those hosts to maintain the consistency of the database replicas. (In
an internet, at least one glbd must run in each network.) Each replica
of the GLB keeps a list of all the other GLB replicas. The drm_admin
tool administers the replication of the GLB database and of the replica
list.
Currently, glbd supports both the DARPA IP and Domain DDS network
protocols. A GLB replica can allow access to its database from both IP
and DDS clients. However, when communicating with each other to maintain
replication of the GLB database, GLB replicas should use only one
protocol family. You choose which family the GLBs will use. In an
internet, all routing nodes must support this family.
If a set of GLB replicas includes any SunOS or ULTRIX systems, all
replicas must use IP protocols to communicate with each other. A replica
running on an Apollo system can communicate with other replicas via IP
protocols but still provide lookup and update services to its clients via
both IP and DDS protocols.
The following subsections briefly describe glbd startup on various
systems. See Managing NCS Software for more detailed information.
Running glbd on SR10 Apollo Systems
If the GLB is to communicate via IP protocols, either with clients or
with other GLB replicas, a TCP daemon (tcpd) must be running on the local
host when glbd is started. Also, regardless of which protocol glbd uses,
a Local Location Broker daemon (llbd) must be running on the local host
when glbd is started.
The TCP and Location Broker daemons should be started in this order:
tcpd, llbd, glbd. The daemons will start automatically in the correct
order at boot time if the files /etc/daemons/tcpd, /etc/daemons/llbd, and
/etc/daemons/glbd exist. Use touch or crf to create these files.
Running glbd on SR9 Apollo Systems
If the GLB is to communicate via IP protocols, either with clients or
with other GLB replicas, a TCP server (tcp_server) must be running on the
local host when glbd is started. Also, regardless of which protocol glbd
uses, a Local Location Broker daemon (llbd) must be running on the local
host when glbd is started.
The TCP server and the Location Broker daemons should be started in this
order: tcp_server, llbd, glbd. Typically, processes are started by the
file `node_data/startup.suffix, where suffix indicates the display type.
Running glbd on SunOS and ULTRIX Systems
On SunOS and ULTRIX systems, the GLB communicates only via IP protocols.
A Local Location Broker daemon (llbd) must be running on the local host
when glbd is started.
Typically, the llbd and glbd processes are started in background at boot
time from /etc/rc. If you start the daemons by hand, you must be root.
OPTIONS
-create Create a replica of the GLB. This option creates a GLB
database in addition to starting a broker process. It must be
used with either -first or -from.
-first This option must be used with the -create option. Use it to
create the first replica (that is, the very first instance) of
the GLB on your network or internet.
-family family_name
This option can be used only in conjunction with the -first
option. It specifies the address family that the first GLB
replica will use to identify itself on the replica list. Any
subsequently created replicas must use this family to
communicate with this replica. Currently, family_name can be
either dds or ip. If this option is not used, the replica will
be identified on the replica list by its DDS address.
-from host_name
This option must be used with the -create option. Use it to
create additional replicas of the GLB. A replica of the GLB
must exist at host_name. The database and replica list for the
new replica are initialized from those at host_name. The
replica at host_name adds an entry for the new replica to its
replica list and propagates the entry to the other GLB
replicas.
A host_name takes the form family:host, where the host can be
specified either by its name or by its network address. For
example, dds://jeeves, dds:#959a.940f, ip:bertie, and
ip:#192.5.5.5 are acceptable host names.
The new replica will use the same address family as host_name
in identifying itself on the replica list. For example, if
host_name is an IP address, the new replica will be listed by
its IP address on the replica list.
-change_family family_name
Use this option only if network reconfigurations require that
you change the address family of every GLB replica; see the
discussion in the "DESCRIPTION" section. Currently,
family_name can be either dds or ip.
For a procedure to change all of your GLB replicas from one
address family to another, see Managing NCS Software.
-listen family_list
This option restricts the address families on which a GLB
listens. Use it only if you are creating a special
configuration where access to a GLB is restricted to a subset
of hosts in the network or internet.
The family_list is a list of the address families on which the
GLB will listen. Names in this list are separated by spaces.
Possible family names include dds and ip.
The GLB will always listen for requests from the family by
which it is listed on the replica list, even if that family is
not specified in family_list.
If glbd is started without the -listen option, the GLB will
listen on all address families that are supported both by NCS
and by the local host. On Apollo systems, this set of families
always includes dds and may also include ip. On most other
systems, ip is currently the only family.
-version Display the version of NCK that this glbd belongs to, but do
not start the daemon.
EXAMPLES
1. Create and start for the first time the first replica of the GLB on
this network or internet:
$ /etc/server /etc/ncs/glbd -create -first -family dds &
2. Start for the first time a subsequent replica of the GLB,
initializing its database from host //jeeves:
$ /etc/server /etc/ncs/glbd -create -from dds://jeeves &
3. Restart an existing replica of the GLB:
$ /etc/server /etc/ncs/glbd &
4. Restart an existing replica of the GLB on remote host //bertie:
$ crp -on //bertie /etc/server //bertie/etc/ncs/glbd &
FILES
On Apollo systems, glbd writes diagnostic output to the file
`node_data/system_logs/glb_log. On other UNIX systems, the log file is
/etc/ncs/glb_log.
SEE ALSO
drm_admin, lb_admin, llbd, glb_obj.txt, glb_site.txt
Managing NCS Software