The glast xrootd setup uses the standard setup for the xrootd installation and log directories:
This page describes the xrootd setup for GLAST.
The GLAST xrootd cluster consists of redirectors and data server. A redirector is the central entrance point for a client.
type |
directory |
---|---|
Installation dir |
/opt/xrootd |
xrootd and cmsd log files |
/var/adm/xrootd/logs |
xrootd and cmsd core files |
/var/adm/xrootd/core |
Taylor installs various xrootd releases into /opt/xrootd of a server. The activate script to enable a particular version. The activate script runs taylor and then creates the /opt/xrootd/prod link that points to the xrootd release to be used. All other scripts (start, stop, ranger) are using the /opt/xrootd/prod path to find binaries and config files.
activate <xrootd-version> For example: > cd /opt/xrootd > activate 20070321-1251p1;
The glast xrootd servers (data servers and redirectors) are configured so that ranger will automatically restart a non running xrootd or olbd daemon. Ranger runs every 15 min.
If you don't want xrootd/cmsd to run remove the link /opt/xrootd/prod. Otherwise ranger will restart the daemons.
The prod/etc directory contains scripts to stop and start the daemons. Most of the times it is the easiest to restart both xrootd and cmsd daemons using the RestartALL script.
> cd /opt/xrootd > ./RestartALL # Restart xrootd and cmsd
On a redirector server only a cmsd and xrootd daemon are running.
On a data server, a few more processes are started depending on the configuration.
For the configuration used by GLAST one should see that the cmsd spawns two processes:
Typically data servers employ more then one file system. In order to provide a single name space Xrootd uses the the cache system provided by the ooss (mps) tools. A cache directory is created for each file system. Files are placed into these cache directories and a link is created from the so called namespace to the file in the cache. The example will illustrate this: