Explain how the template works.

Dell_MD38XX/README.md

+Using the Dell MD38XX template
+==============================
+
+What is this package for
+------------------------
+
+This package contains record definition and scripts used to query
+Dell MD38XX devices and gather performance statistics.
+It also contains the template which should be applied to a properly configured
+node.
+
+I originally wanted to run one discovery script, create one
+"virtual" host for each array and within each virtual host execute a) a
+second discovery script and b) a script to fill records. Honestly, I did not
+manage to achieve this so I am doing things differently.
+
+The template works as follows:
+   * a discovery script finds all devices (Storage Array, RAID Controller,
+     Disk Group, Disk Pool). For each device a set of items is created: since 
+     all interactions with the storage array involve running the `SMcli` 
+     executable, which is very "heavy" and slow, the items are of type
+     `Zabbix trapper`, which means they are filled by a `push` from the
+     monitored node;
+   * a second discovery script is executed, to discover storage arrays whose
+     name matches (-m argument) some pattern;
+   * for each array discovered by the previous script, an item is defined 
+     which is responsible for executing the statistics gathering script and
+     running `zabbix_sender`
+
+By default, the statistics gathering script runs every 2 minutes, executing
+a performance monitor session lasting 5 seconds.
+
+
+Software installation and configuration
+---------------------------------------
+
+It is assumed that SM*rpm packages have already been installed.
+At time of writing, and for CentOS, these are:
+   * SMruntime-11.25.0A06.0004-1.x86_64
+   * SMesm-11.25.0G06.0002-1.noarch
+   * SMclient-11.25.0G06.0026-1.noarch
+
+Make your disk storage arrays known to the monitoring machine
+by registering them with the command::
+
+   sudo SMcli -A <IP_address1> <IP_address2>
+   
+See what arrays have been registered with the command::
+
+   sudo SMcli -d -i
+   
+Pick one array and check whether you can successfully query
+performance statistics, for example::
+
+   sudo /bin/SMcli 10.200.4.144  10.200.4.145 -e -c 'set session performanceMonitorInterval=5 performanceMonitorIterations=1 ; save storageArray performanceStats file=\"/tmp/perf.log\";'
+   
+Discovery configuration
+-----------------------
+
+Define a global regular expression to exclude devices for which you are
+not interested in gathering extensive information. In our case, we exclude
+the disk groups which are presented to Ceph servers, with names like `R2S1E0D3-02`
+(disk group in Rack 2, Storage Array 1, Enclosure 0, Drawer 3, 2nd disk picked
+from such drawer) with the expression::
+
+   Name: Dell MD38XX devices for discovery
+   Expression type: Result is FALSE
+   Expression: ^\w\d\w\d.*
+   
+In the discovery rule `DELL MD38XX discovery Devices via SMcli` we thus filter
+on::
+
+   {#DEVNAME} matches @Dell MD38XX devices for discovery
+   
+
+
+
+
+