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Browsing Grid Resources
It is possible for users and administrators of a Grid system to find out information about various resources of a Grid. The Information Service (IS) provides information about the EGEE/LCG-2 Grid resources and their status [3.1]?. It is through the information service that available CEs? to run jobs can be located, and the SEs? holding replicas of Grid files and the catalogs keeping the information on these files are found. This published information is also important for monitoring and accounting purposes.
The GLUE Schema
The data published by IS conforms to the GLUE (Grid Laboratory for a Uniform Environment) schema [3.2]?. The GLUE schema defines a common conceptual data model to be used for Grid resource monitory and discovery. There are three main components of the GLUE schema; they describe the attributes and values of CEs?, SEs? and binding information for CEs? and SEs?.
EGEE currently uses the Monitoring and Discovery Service (MDS) by Globus as the main provider of the information service. The new Relational Grid Monitoring Architecture (R-GMA) has also been deployed in EGEE/LCG-2 type Grids, however our focus will only be on MDS.
Monitoring and Discovery Service
The MDS implements the GLUE Schema using OpenLDAP?; an Open Source implementation of the Lightweight Directory Access Protocol (LDAP) [3.3, 3.4, 3.5]?. LDAP is a special form of a database which is optimised for reading, browsing and searching data. LDAP information model is based on entries and those entries describe objects such as employees of a company, computers, and servers. Each of these entries (i.e. objects) contains one or more attributes that describes the entry. Each of these attributes has a type and one or more values. Each entry in the LDAP is uniquely identified by a Distinguish Name (DN). A DN is formed by sequence of attributes and values. Based on the DNs? the objects can be arranged into a hierarchical tree like structure called the Directory Information Tree (DIT). Figure 3.1 shows an example of a hypothetical DIT.
Figure 3.1 - An example of a hypothetical directory information tree.
In figure 3.1 the root entry defines the site and site specific information is given as a separate entry in the next level. Similarly, CEs? and SEs? under the site is in the second level. Then SE specific entries such as file catalog and disk status is in the third level. The DN of a particular CE is formed by attribute identifying the site (Site_ID=gridats) and attribute identifying the CE (CE_ID=baciuco.grid.it). Therefore the complete DN would be similar to CE_ID=baciuco.grid.it,Site_ID=gridats.
Figure 3.2 - DIT of the Storage Resources
An actual DIT of a Grid is much more complex than figure 3.1. Just to give you a brief idea, let us look at a more realistic DIT that depicts SEs? of a Grid. Figure 3.2 shows the GLUE schema DIT for storage resources at a site, as published by the site GRIS. All of the site entries are grouped under the "o=grid,mds-vo-name=local" root entries. For each SE host at the site, a "GlueSEUniqueID?" entry is present, and the value of the "GlueSEUniqueID?" is exactly the SE hostname; under each of these "GlueSEUniqueID?" entries are one or more "GlueSARoot?" entries, specifying the path(s), in the SE host file system, where Grid data is stored. The full DIT is much more complicated and comprises entries for the computing resources, and other services (LFC, RB, etc.).
The kind of information can be stored as entries in the DIT are specified in the LDAP Schema. The schema defines object classes, their attributes and value types. The EGEE implementation of OpenLDAP? does not require any authentication (i.e. all users can browse the catalog and all services are allowed to enter or modify information into it).
Figure 3.3 - The MDS information service
Figure 3.3 show how the information is stored and propagated in a EGEE-based Grid. On the CE and SEs? runs a program named "Information Provider", which monitors local resources and publishes entries describing their status (both static and dynamic) on the local GRIS LDAP database. The Grid Resource Information Server (GRIS) publishes this status information via an LDAP server.
In each site an element called the Berkeley Database Information Index (BDII) [3.6]? compiles all the data from different GRISs? and publishes it (from user perspective, there is no difference between a BDII and GRIS). The current implementation of EGEE recommends the use of Berkeley Database Information Index (BDII) [3.6]? due to its higher stability. This BDII is called the Site BDII and make use of LDAP.
A BDII is also used at the top of the IS hierarchy. This BDII queries all the GIISes? (or site BDIIs?) and act as a cache storing information about the Grid status in its database. Therefore by querying the top most BDII a user or a service can access all the available information about the Grid. It is also possible to get information about a specific resource by querying individual site GIISes?, site BDIIs? or local GRISs?. This information can be up-to-date compared to what is in the top BDII.
The lcg-infosites command
The lcg-infosites command can be used as an easy way to retrieve information on grid resources for the most common user needs. The command has the following format; meaning of attributes and options are summarised in table 3.1:
lcg-infosites --vo [vo name]? request -v [verbose level]? -h --is [DBII to query]?
To get a detailed description on lcg-infosites command use the following:
$ lcg-infosites -h
| Request | Description |
|---|---|
| all | It groups together the information provided by CE, SE, LRC and RMC. |
| ce | The information relative to number of CPUs?, running jobs, waiting jobs and names of the CEs? are provided. |
| closeSE | The names of the CEs? where the user's VO is allowed to run together with their corresponding closest SEs? are provided. |
| lfc | The name of the machine hosting the LFC catalog is printed. |
| lrc rmc | The LRC/RMC services are obsolete. |
| se | The names of the SEs? supported by the user's VO together with their types, available & used space are printed. |
| tag | The names of the tags relative to the software installed in site are printed together with the corresponding CEs?. |
| Option | Description |
|---|---|
| --vo | Name of the VO (mandatory) |
| -v | For Computing Elements:
For Storage Elements:
|
| -h, --help | Display help |
| --is | BDII user wishes to query. In case this argument is not supplied, the BDII defined into the LCG_GFAL_INFOSYS environment variable will be queried. |
Listing CEs? and queues
For instance, let us try to obtain information about computing resources of gridats. Use the following command:
$ lcg-infosites --vo gridats ce
A typical output is as follows:
**************************************************************** These are the related data for gridats: (in terms of queues and CPUs) **************************************************************** #CPU Free Total Jobs Running Waiting ComputingElement ---------------------------------------------------------- 38 38 0 0 0 grid001.oat.ts.astro.it:2119/jobmanager-lcgpbs-grid 4 2 0 2 0 ce-01.grid.sissa.it:2119/jobmanager-lcgpbs-gridats 10 2 0 0 0 baciuco.grid.sissa.it:2119/jobmanager-pbs-gridats 10 10 0 0 0 egrid.create-net.org:2119/jobmanager-lcgpbs-gridats 8 0 0 0 0 egrid-ce-01.egrid.it:2119/jobmanager-lcgpbs-gridats
The verbose level option -v can be used to control the amount of information displayed on screen. The verbose level is given by either an integer. The higher the number, the more amount of information is displayed.
Compare the following outputs of lcg-infosistes ce at verbose levels 1 and 2.
$ lcg-infosites --vo gridats -v 1 ce ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-long grid001.oat.ts.astro.it:2119/jobmanager-lcgpbs-gridats ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-short ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-infinite egrid-ce-01.egrid.it:2119/jobmanager-lcgpbs-gridats gridts01.grid.elettra.trieste.it:2119/jobmanager-lcgpbs-gridats
$ lcg-infosites --vo gridats -v 2 ce
RAMMemory Operating System System Version Processor Subcluster name
-------------------------------------------------------------------------------------------------------------------------
513 Scientific Linux SL 3.0.7 PIII ce-02.grid.sissa.it
2048 Scientific Linux CERN SLC PIII grid001.oat.ts.astro.it
513 Scientific Linux SL 3.0.7 PIII ce-02.grid.sissa.it
1025228 SL 3 PIII egrid-ce-01.egrid.it
1024 SLC 3 PIV gridts01.grid.elettra.trieste.it
Listing SEs?
Retrieve the information about storage elements using the following command:
$ lcg-infosites --vo gridats se
A typical output is as follows:
Avail Space(Kb) Used Space(Kb) Type SEs ---------------------------------------------------------- 688004000 874446272 n.a grid002.oat.ts.astro.it 13659804 1054456 n.a egrid-ce-01.egrid.it 169452728 7753952 n.a gridts01.grid.elettra.trieste.it
The verbose level option -v can be used to control the amount of information displayed on screen. The verbose level is given by either an integer. The higher the number, the more amount of information is displayed.
The SE listing only admits verbose level 1:
$ lcg-infosites --vo gridats -v 1 se grid002.oat.ts.astro.it egrid-ce-01.egrid.it gridts01.grid.elettra.trieste.it
Listing CEs? and SEs? together
The request all can be used to retrieve information on both CEs? nd SEs? at the same time. If you type:
$ lcg-infosites --vo gridats all
Then you will see results for the two sections above appearing one after another.
Inspecting the CEs? and SEs? proximity relation
With the request closeSE, you can retrieve the names of the CEs? where our VO (in this case gridats) is allowed to run together with the corresponding closest SEs?. Use the following command:
$ lcg-infosites --vo gridats closeSE
A typical output is as follows:
Name of the CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-long
ce-02.grid.sissa.it
Name of the CE: grid001.oat.ts.astro.it:2119/jobmanager-lcgpbs-gridats
grid002.oat.ts.astro.it
Name of the CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-short
ce-02.grid.sissa.it
Name of the CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-infinite
ce-02.grid.sissa.it
Name of the CE: egrid-ce-01.egrid.it:2119/jobmanager-lcgpbs-gridats
egrid-ce-01.egrid.it
Name of the CE: gridts01.grid.elettra.trieste.it:2119/jobmanager-lcgpbs-gridats
gridts01.grid.elettra.trieste.it
Listing the LFC server hostname
The name of the LFC (LCG File Catalog) from a given Grid (i.e. gridats) can be found out using the lfc request. Use the following command:
$ lcg-infosites --vo gridats lfc gridts05.grid.elettra.trieste.it
Listing installed software tags
The name of the tags relative to the software installed in a site (i.e. gridats) together with the corresponding CEs? can be printed using the tag option. Following is an illustration of the command (we use the egrid VO, since gridats uses no software tags at present):
$ lcg-infosites --vo egrid tag
valor del bdii: egee-bdii.cnaf.infn.it:2170
Name of the CE: gridce.ilc.cnr.it
Name of the CE: gridba2.ba.infn.it
VO-egrid-client
Name of the CE: grid002.ca.infn.it
Name of the CE: grid012.ct.infn.it
VO-egrid-Python_2.3_1
VO-egrid-Python-2.3
VO-egrid-uberftp-VDT1.2.0
VO-egrid-eurl
VO-egrid-egrid-transform-dispatcher
VO-egrid-transform-nyse-taq
VO-egrid-etool
VO-egrid-scilab-4.0
VO-egrid-octave-2.1.73
VO-egrid-scilab
VO-egrid-octave
VO-egrid-client
[.........]
The lcg-info command
The lcg-info command can be used to list either CEs? or SEs? that satisfy a given set of conditions on their attributes, and to print, for each of them the values of a given set of attributes. The information is taken from the BDII specified by the LCG_GFAL_INFOSYS environment variable or given through the command line. The command has the following format and meaning of each option is summarised in table 3.3:
lcg-info [--list-ce] [--list-se] [--query
<user query>] [--attrs <user attributes>] -vo
<vo name> --sed --help --list-attrs
Note
Note:
If --list-ce is specified then only CE attributes are considered and if only --list-se is specified then only SE attributes are considered, not both. The attributes used with --attrs or used within --query expressions are a subset of GLUE schema, those that are most relevant to the user.
Note
Note:
To use the lcg-info command Perl-based LDAP packages (for the Net::LDAP PERL module) and Perl documentation (for the POD::Usage PERL module) should be installed on your system. If not, you will get an error message when you try to use the lcg-info command. See section 2.1.2 on how to install necessary packages.
| --help | Prints the manual page and exits. |
| --list-attrs | Prints a list of the attributes that can be queried. |
| --list-ce | Lists the CEs? which satisfy a query, or all the CEs? if no query is given. |
| --list-se | Lists the SEs? which satisfy a query, or all the SEs? if no query is given. |
| --query | Restricts the output to the CEs? (SEs?) which satisfy the given query. |
| --bdii | Allows to specify a BDII in the form <hostname>:<port>. If not given, the value of the environmental variable LCG_GFAL_INFOSYS is used. If that is not defined, the command returns an error. |
| --sed | Prints the output in a "sed-friendly" format: % separate the CE (SE) identifier and the printed attributes, & separate the values of multi-valued attributes. |
| --quiet | Suppresses warning messages. |
| --attrs | Specifies the attributes whose values should be printed. |
| --vo | Restricts the output to CEs? or SEs? where the given VO is authorized. Mandatory when VO-dependent attributes are queried upon. |
To find out more information about the command, invoke it with the --help option. Use the following command:
$ lcg-info --help
To list the attributes supported by lcg-info command, use the following command line:
$ lcg-info --list-attrs WaitingJobs GlueCE GlueCEStateWaitingJobs MaxCPUTime GlueCE GlueCEPolicyMaxCPUTime MaxTotalJobs GlueCE GlueCEPolicyMaxTotalJobs CEStatus GlueCE GlueCEStateStatus CEVOs GlueCE GlueCEAccessControlBaseRule FreeCPUs GlueCE GlueCEStateFreeCPUs RunningJobs GlueCE GlueCEStateRunningJobs MaxWCTime GlueCE GlueCEPolicyMaxWallClockTime Accesspoint GlueCESEBind GlueCESEBindCEAccesspoint CloseCE GlueCESEBindGroup GlueCESEBindGroupCEUniqueID CloseSE GlueCESEBindGroup GlueCESEBindGroupSEUniqueID AvailableSpace GlueSA GlueSAStateAvailableSpace Path GlueSA GlueSAPath SEVOs GlueSA GlueSAAccessControlBaseRule UsedSpace GlueSA GlueSAStateUsedSpace Root GlueSA GlueSARoot SESite GlueSE GlueForeignKey SEName GlueSE GlueSEName SE GlueSE GlueSEUniqueID SEType GlueSE GlueSEType SEPort GlueSE GlueSEPort SEArch GlueSE GlueSEArchitecture Protocol GlueSEAccessProtocol GlueSEAccessProtocolType ArchType GlueSL GlueSLArchitectureType SMPSize GlueSubCluster GlueHostArchitectureSMPSize Processor GlueSubCluster GlueHostProcessorModel OS GlueSubCluster GlueHostOperatingSystemName Cluster GlueSubCluster GlueSubClusterUniqueID Tag GlueSubCluster GlueHostApplicationSoftwareRunTimeEnvironment CINT2000 GlueSubCluster GlueHostBenchmarkSI00 OSVersion GlueSubCluster GlueHostOperatingSystemVersion CFP2000 GlueSubCluster GlueHostBenchmarkSF00 OSRelease GlueSubCluster GlueHostOperatingSystemRelease ClockSpeed GlueSubCluster GlueHostProcessorClockSpeed Memory GlueSubCluster GlueHostMainMemoryRAMSize
For each attribute the simplified attribute name used by lcg-info, the corresponding object class and the GLUE attribute name are given [3.1, 3.2]?.
Listing and querying information on CEs? with lcg-info
Let us try to find out list of computing elements vailable. For this we use the --list-ce option as given in the following example:
$ lcg-info --list-ce
The output is similar to the following:
- CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-infinite - CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-long - CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-short - CE: egrid-ce-01.egrid.it:2119/jobmanager-lcgpbs-egrid - CE: egrid-ce-01.egrid.it:2119/jobmanager-lcgpbs-gridats - CE: egrid-ce-01.egrid.it:2119/jobmanager-lcgpbs-stormdev - CE: grid001.oat.ts.astro.it:2119/jobmanager-lcgpbs-cert - CE: grid001.oat.ts.astro.it:2119/jobmanager-lcgpbs-grid - CE: grid001.oat.ts.astro.it:2119/jobmanager-lcgpbs-gridats - CE: gridts01.grid.elettra.trieste.it:2119/jobmanager-lcgpbs-gridats
To find out list of computing elements only related to gridats, we need to specifically indicate the VO using --vo option:
$ lcg-info --list-ce --vo gridats - CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-infinite - CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-long - CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-short - CE: egrid-ce-01.egrid.it:2119/jobmanager-lcgpbs-gridats - CE: grid001.oat.ts.astro.it:2119/jobmanager-lcgpbs-gridats - CE: gridts01.grid.elettra.trieste.it:2119/jobmanager-lcgpbs-gridats
Let us further extend out command to find out the total number of CPU (TotalCPUs?) and free ones (FreeCPUs?). The --vo attribute must be provided since we are querying for attributes (table 3.2). Make sure to put the attributes one after another separated by comas (,) within single-quotes ('). No spaces should be kept between attributes.
$ lcg-info --list-ce \
--attrs 'TotalCPUs,FreeCPUs' --vo gridats
- CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-infinite
- TotalCPUs 2
- FreeCPUs 2
- CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-long
- TotalCPUs 2
- FreeCPUs 2
- CE: ce-02.grid.sissa.it:2119/jobmanager-lcgpbs-short
- TotalCPUs 2
- FreeCPUs 2
- CE: egrid-ce-01.egrid.it:2119/jobmanager-lcgpbs-gridats
- TotalCPUs 6
- FreeCPUs 5
- CE: grid001.oat.ts.astro.it:2119/jobmanager-lcgpbs-gridats
- TotalCPUs 44
- FreeCPUs 28
- CE: gridts01.grid.elettra.trieste.it:2119/jobmanager-lcgpbs-gridats
- TotalCPUs 22
- FreeCPUs 22
Let's make our command further complicated by trying to find out machines with exactly 6 CPUs?:
$ lcg-info --list-ce \
--query 'TotalCPUs=10' \
--attrs 'TotalCPUs,FreeCPUs' \
--vo gridats
- CE: egrid-ce-01.egrid.it:2119/jobmanager-lcgpbs-gridats
- TotalCPUs 6
- FreeCPUs 5
Note
Note:
It must be stressed that lcg-info command only supports a logical AND of logical expressions, separated by commas, and the allowed operators are >=, <= and =. The * symbol matches any number of characters.
Use the following command to locate any CE running "Debian" as he operating system and which is part of gridats; use the OS attribute to construct a query:
$ lcg-info --list-ce \
--query 'OS=Debian' --vo gridats
- CE: ce-01.grid.sissa.it:2119/jobmanager-lcgpbs-gridats
- CE: egrid.create-net.org:2119/jobmanager-lcgpbs-gridats
Use the OS and OSVersion? attributes to list the OS name and version:
$ lcg-info --list-ce \
--query 'OS=Debian' \
--vo gridats \
--attrs 'OS,OSVersion'
- CE: ce-01.grid.sissa.it:2119/jobmanager-lcgpbs-gridats
- OS Debian
- OSVersion 3
- CE: egrid.create-net.org:2119/jobmanager-lcgpbs-gridats
- OS Debian
- OSVersion 3
Listing and querying information on SEs? with lcg-info
So far our focus was only on computing elements. Let us try to find out information about storage elements using lcg-info command. Use the following command to list SEs? in gridats:
$ lcg-info --list-se --vo gridats - SE: baciuco.grid.sissa.it - SE: ce-01.grid.sissa.it - SE: egrid-ce-01.egrid.it - SE: egrid.create-net.org - SE: grid001.oat.ts.astro.it
The following command uses the UsedSpace? and AvailableSpace? attributes to find out used and free space in each SE:
$ lcg-info --list-se \
--attrs 'UsedSpace,AvailableSpace' \
--vo gridats
- SE: egrid-ce-01.egrid.it
- UsedSpace 1054456
- AvailableSpace 13659804
- SE: grid002.oat.ts.astro.it
- UsedSpace 874446272
- AvailableSpace 688004000
- SE: gridts01.grid.elettra.trieste.it
- UsedSpace 7753952
- AvailableSpace 169452728
Querying the local GRIS directly
The local GRISes? running on CEs? and SEs? reports both static and dynamic information on the characteristics and status of services. This information can be directly accessed using ldapsearch command.
In order to access the GRIS on specific Grid elements the host name and the TCP port where GRIS run must be known. The default port number is 2135.
As an example use the following command to access GRIS running on host baciuco.grid.sissa.it:
ldapsearch -x -h baciuco.grid.sissa.it -p 2135 -b "mds-vo-name=local,o=grid"
Where the -x option indicates that simple authentication to be used; the -h and``-p`` options precede the host name and port respectively; and the -b option is used to specify the initial entry for the search in the LDAP tree. For a GRIS, the initial entry of the DIT is always o=grid, and the second one (next level) is mds-vo-name=local. It is in the entries in the deeper levels, that the actual resource information is shown. That is why mds-vo-name=local,o=grid is used as DN of the initial node for the search.
The result of the command can be very long. Therefore understanding hierarchy (objects, attributes and their relationships) will not be so easy. In order to restrict the search, filters can be used; the filters are applied on given attributes and conditions. The operator used in a filter can be one of the following:
- =
- Entries whose attribute is equal to the value
- >=
- Entries whose attribute is greater than or equal to the value
- <=
- Entries whose attribute is less than or equal to the value
- =*
- Entries that have a value set for that attribute
- ~=
Entries whose string attribute value approximately matches the specified value; the SOUNDEX algorithm is used for comparison.
Complex search filters can be formed by using Boolean operators to combine constraints. The Boolean operators that can be used are: AND (&), OR (|) and NOT (!).
Using a graphical LDAP Browser
However to make things simple and clear we can make use of a graphically LDAP browser. There are various commercial as well as Open Source LDAP client utilities. Those provide a clear and hierarchical representation of data. Searching and navigating (or even editing of values) with such tools is really easy. For rest of the examples we will be using the LDAP BrowserEditor? [3.7]? by Jarek Gawor which is free for educational user.
Installing the LDAP BrowserEditor?
Installing LDAP BrowserEditor? is really simple however you must have Java 1.2 or higher installed on your machine (if not see section 2.1.3 on installing Java).
- Step 1
Download the LDAP BrowserEditor? from:
http://www-unix.mcs.anl.gov/~gawor/ldap/
Download the latest Browser<version>.tar.gz file.
- Step 2
Uncompress and extract archive:
$ gunzip Browser"version".tar.gz
It will be extracted to a new directly called ldapbrowser. You may move the ldapbrowser directory to a different location if needed.
If the ldapbrowser directory is created and if it is not empty the installation is complete.
Running the LDAP BrowserEditor?
- Step 1
To execute the LDAP BrowserEditor? use the following commands. Before running change the directory to ldapbrowser, then execute the lbe.sh script as follows:
$ cd ldapbrowser $ ./lbe.sh
Then the Connect dialog box appears (figure 3.4). This dialog box can be used to create and manage connections to LDAP servers which are referred as sessions. By default it has a connection to LDAP server running in University of Michigan (ldap.itd.umich.edu).
Figure 3.4 - The Connect dialog box
- Step 2
Select uofmichigan from the Session List: list box then, click the Edit Button. You will observer the configuration parameters for uofmichigan session and how those are given (figure 3.5).
Close the dialog by clicking the Close button.
Figure 3.5 - The Edit Session dialog box
- Step 3
Then click the Connect button on the Connect dialog box. After couple of seconds you will be connected to the University of Michigan LDAP server. You may not be able to browse any values however use the main window to identify different components (figure 3.6).
Figure 3.6 - The main window of the LDAP BrowserEditor?
- Step 4
- Close the connection by selecting File -> Disconnect from the menu.
Browsing Grid Resources with LDAP Browser
- Step 1
Let us connect to the gridts04.grid.elettra.trieste.it (is a CE having some SE capabilities as well) and observer its parameters.
To reopen the Connection dialog back click File -> Connect menu or the shortcut key Ctrl+C. Then the connection dialog box should appear.
- Step 2
Click New button to create a new connection. Then the New Session dialog box appears. In the New Session dialog box, click the Name tab. Then enter gridts04 in the text box labelled Name:.
Select the Connection tab. Enter the following values in the Host Info pane:
Host: gridts04.grid.elettra.trieste.it
Port: 2170
Base DN: mds-vo-name=local, o=grid
..note:: Note:
You do not need to provide anything under User Info pane since EGEE base Grids allow anonymous access to the catalog.
- Step 3
Then click the Save button to save the new parameters.
Figure 3.7 - Left pane in LDAP Browser/Editor main window
Figure 3.8 - The main window indicating objects and corresponding attributes
- Step 4
Select gridts04 from the list box labelled Session List: and click Connect button.
After few seconds you will see the DIT of gridts04 (figure 3.7) appearing on the left of the main window. The LDAP objects are displayed in the form of a tree and all attributes of the entries in the form of a table (right of the window called the attributes pane).
- Step 5
Browse through other objects and attributes listed. Try to find out the answer to the following questions by browsing the various object and their attributes.
- Step 6
Locating certain attributes can take a while when there is lots of information on the DIT. You can use the search facility to find out values of specific attributes. In order to do so, you must know the GLUE attribute name.
Suppose you want to find the amount of memory. The GLUE attribute used to hold memory (RAM size) is GlueHostMainMemoryRAMSize?.
Select the top most object from the DIT. Then select View -> Search from the menu. The Search dialog box appears (figure 3.9).
Figure 3.9 - The Search dialog box
Type GlueHostMainMemoryRAMSize? in the text box labelled Attributes:.
Then click the Search button.
By default it will search attributes only at one-level. If the search need to be performed even on sub trees select the Sub-tree level radio button under the Search scope:.
Figure 3.10 illustrates an output of the above search.
Figure 3.10 - Results of a search query
Results of the search operation depend on the current object that is selected on the DIT. So if the desired result is not available try selecting a possible object from the DIT. A short cut could be to start with the DN (mds-vo-name=local,o=grid) which is at the top of the DIT. Then it will search for all sub-trees under it.
- Step 7
Try to find out information on the following attributes. Also, note the objects and DNs? of the objects that they belong to.
GlueCEInfoTotalCPUs?
GlueCEStateFreeCPUs?
GlueSAStateAvailableSpace?
GlueHostOperatingSystemName?
GlueHostOperatingSystemVersion?
GlueHostProcessorClockSpeed?
- Step 8
Rather than querying individual site GIISes?, site BDIIs? or local GRISes? of CEs? and SEs?, we can also query the top most BDII.
Let us try to connect to the top most BDII for gridats which is accessible through port 2170 of gridts04.grid.elettra.trieste.it.
Use the LDAP BrowserEditor? and create a new session called Top BDII. Then connect to the top most BDII and browse its objects and parameters. Look for various CEs? and SEs? under it.
