The info-provider takes as much information as possible from
dCache. To achieve this, it needs the internal
information-collecting service, info, to be running and a
means to collect that information: httpd. Make sure that
both the httpd and info services are running
within your dCache instance. By default, the info
service is started on the admin-node; but it is possible to
configure dCache so it runs on a different node. You should
run only one info service per dCache instance.
The traditional (pre-1.9.7) allocation of services to domains
has the info cell running in the infoDomain domain. A
dCache system that has been migrated from this old
configuration will have the following fragment in the node’s
layout file:
[infoDomain] [infoDomain/info]
It is also possible to run the info service inside a
domain that runs other services. The following example show the
information domain that hosts the admin,
httpd, topo and info services.
[information] [information/admin] [information/httpd] [information/topo] [information/info]
For more information on configuring dCache layout files, see the section called “Defining domains and services”.
Use the dcache services command to see if a
particular node is configured to run the info service.
The following shows the output if the node has an
information domain that is configured to run the
info cell.
[root] #dcache services | grep infoinformation info info /var/log/dCache/information.log
If a node has no domain configured to host the info
service then the above dcache services
command will give no output:
[root] #dcache services | grep info
If no running domain within any node of
your dCache instance is running the info service then
you must add the service to a domain and restart that domain.
Example:
In this example, the info service is added to the
example domain. Note that the specific choice of
domain (example) is just to give a concrete example;
the same process may be applied to a different domain.
The layouts file for this node includes the following
definition for the example domain:
[example] [example/admin] [example/httpd] [example/topo]
By adding the extra line [example/info]
to the layouts file, in future, the example
domain will host the info service.
[example] [example/admin] [example/httpd] [example/topo] [example/info]
To actually start the info cell, the
example domain must be restarted.
[root] #dcache restart exampleStopping example (pid=30471) 0 done Starting example done
With the example domain restarted, the info
service is now running.
You can also verify both the httpd and info
services are running using the wget command.
The specific command assumes that you are logged into the node
that has the httpd service (by default, the admin node).
You may run the command on any node by replacing localhost with the hostname of
the node running the httpd service.
The following example shows the output from the
wget when the info service is running
correctly:
[root] #wget -O/dev/null http://localhost:2288/info--17:57:38-- http://localhost:2288/info Resolving localhost... 127.0.0.1 Connecting to localhost|127.0.0.1|:2288... connected. HTTP request sent, awaiting response... 200 Document follows Length: 372962 (364K) [application/xml] Saving to: `/dev/null' 100%[=========================================================================== ===>] 372,962 --.-K/s in 0.001s 17:57:38 (346 MB/s) - `/dev/null' saved [372962/372962]
If the httpd service isn’t running then the command will
generate the following output:
[root] #wget -O/dev/null http://localhost:2288/info--10:05:35-- http://localhost:2288/info => `/dev/null' Resolving localhost... 127.0.0.1 Connecting to localhost|127.0.0.1|:2288... failed: Connection refused.
To fix the problem, ensure that the httpd service is
running within your dCache instance. This is the service that
provides the web server monitoring within dCache. To enable
the service, follow the same procedure for enabling the
info cell, but add the httpd service within one of
the domains in dCache.
If running the wget command gives an error
message with Unable to contact the info cell. Please
ensure the info cell is running:
[root] #wget -O/dev/null http://localhost:2288/info--10:03:13-- http://localhost:2288/info => `/dev/null' Resolving localhost... 127.0.0.1 Connecting to localhost|127.0.0.1|:2288... connected. HTTP request sent, awaiting response... 503 Unable to contact the info cell. Pl ease ensure the info cell is running. 10:03:13 ERROR 503: Unable to contact the info cell. Please ensure the info cel l is running..
This means that the info service is not running. Follow
the instructions for starting the info service given
above.