The STAR Web Repository
lia.Monitor.LUSs = monalisa.cern.ch,monalisa.cacr.caltech.edu lia.Monitor.group = starUpon discovering the available ML services the "pseudo-client" subscribes to these services and indicates the type of monitoring data it would like to collect by a set of predicates. The predicates are, basically, regular expressions (seperated by comma) with the following structure:
lia.Monitor.JiniClient.Store.predicates=*/Master/*/-1/-1/Load5|%_IN|%_OUT,*/WAN/*The local ML Monitoring Service starts a new thread to serve each pseudo-client that subscribes with it. The pseudo-client receives all the data that match the predicate, but what actually gets stored in the DB tables of the Repository is not the raw data.
|total_time||The total time in secs that will keep data in a table. Data older than total_time will be removed from the table.|
|samples||Number of samples in the table. total_time/samples gives the time interval between samples.|
There is a total of 9 tables in the mon_data database. monitor_1hour is the mediated table that stores data for the last one hour and is the most frequently accessed table. Data older than one hour are removed from the table. monitor_1hour_nm is the unmediated table that stores the received data as is. The rectime column in all tables is the time when the data were entered in the table, not when the data were collected. This is true even for the unmediated table in which data is entered as is. Under util/ShowStoreConfig there is a utility that reads the configuration file and displays the storage configuration: a list of tables with the values for their parameters.
Utilities are provided in the form of shell scripts under the util/SimpleDBShell directory to access locally the database tables. All scripts access data in the monitor_1hour table.
I had no problems accessing the Grid3 MySQL service:
[monalisa@lin003 bin]$ ./mysql -h monalisa-starlight.cern.ch -u mon_user -p Enter password: Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 1244 to server version: 4.0.18-standard Type 'help;' or '\h' for help. Type '\c' to clear the buffer. mysql>but I did have problems accesing the Star MySQL service:
[monalisa@lin003 bin]$ ./mysql -h monalisa-starlight.cern.ch -P 3333 -u mon_user -p Enter password: ERROR 2003: Can't connect to MySQL server on 'monalisa-starlight.cern.ch' (111)It might be a firewall/blocked port issue.
If, however, we compare the values retrieved from the local service to those in the unmediated table monitor_1hour_nm then the values of the parameters are identical except of the rectime parameter. The rectime parameter is the time that the data were entered into the table and since we are looking at two different DBs (one in the repository and one in the local ML service), there is a difference in the recording time. The time difference is of the order of 2-3 seconds.
Also, there seems to be a delay in the data in the Web Repository DB tables.
If, for example, I request the latest value of a parameter from the
monitor_1hour_nm DB table and compare the rectime
to the latest value of the local ML service, the
Web repository will be about 1 minute behind. In other words, the latest
value in the DB of the repository is about 1 minute old compared to the one in the
local ML service.
According to the ML developers this 1 minute delay is caused because the monitoring data that the "pseudo-client" gets from the ML services is first cached into a buffer and then flushed onto the disk every 1 minute. The reason for buffering the data is that some filters need to be applied to the data before writing them to the DB. Since the Web Service Client gets the data from the DB the data will be about 1 minute old. The data for the history plots come from the DB also and thus they have the same delay. The data for the real-time plots, however, get plotted as soon as they are retrieved by the "pseudo-client". Thus, we should not get the 1 minute delay in the real-time plots.
The Web Front for the STAR Web Repository can be accesed at: http://monalisa-starlight.cern.ch:8888/
Stratos Efstathiadis - page was last modified