Linux Logical Volume Monitor

Linux uses a Logical Volume Manager (LVM) to manage, at a logical level, all of the file systems and directories created within an Linux system. The LVM maps data between logical and physical storage, allowing data to be non-contiguous, span multiple disks, flexible and dynamically expanded.

The Linux Logical Volume Monitor checks the Volume Group, Physical Volumes and Logical Volumes of the Linux system as defined in the LVM.

  • Volume Groups: The containers for both the Physical and Logical Volumes
  • Physical Volumes: The Physical Volumes are segmented into physical partitions
  • Logical Volumes: The Logical Volumes are logical partitions logged to the physical partitions

Rule criteria change depending on the type of logical volume being monitored. However for each Monitor Type it is possible to specify if a logical volume exists, does not exist or if a performance type triggers user-defined criteria.

Specifying the instance of the Logical Volume to which this rule criteria applies allows the entry of a full path to the required instance or the use of Wildcards ‘*’ and ‘?’ to create a generic entry. Regular expressions can also be entered by changing the entry in the first drop down choice menu from Wildcard to Regex and entering a valid Regular Expression in the second drop-down choice menu.

Wildcards and regular expressions can be used to create generic rules that can then be included in a template in order to monitor multiple systems.

NOTE: In previous versions of Network Server Suite, defining an instance that was not subsequently found by the rule criteria resulted in an error being sent to theEnterprise Console. Due to the methodology used in processing Wildcard and Regular Expression entries, this no longer happens. It is recommended that you define specific ‘Does Not Exist’ rules to raise an alert in these circumstances.
Practical Examples
  • A stale physical partition is a physical partition which contains data that you cannot use. Monitoring for Stale Physical Partitions alerts you when this happens so that you can take correcting action to update the stale partitions so that they contain the same information as valid physical partitions.
  • Monitoring for Free Physical Partitions can alert you to when a low level of space remains on your Linux system.

Adding Linux Logical Volume rule criteria

TIP: When setting criteria, click Display Status to open the Logical Volume Status dialog which displays the individual properties of each of the three Logical Volume monitor types and allows for more precise rule entry.
  1. From the Linux system in the Systems panel of Central Configuration Manager, select Linux Logical Volume Monitor and click Add Rule.
  2. From the Add Rule Detail dialog, click Criteria. Click Add Criteria to open the Logical Volume Criteria dialog.

There are three pages to complete when adding Linux Logical Volume rule criteria.

Category section

This section is used to define the type of volume to monitor and the trigger criteria.

Monitor Type

Use the drop-down menu to select the type of Logical Volume to be monitored: 

  • Volume Group
  • Physical Volume
  • Logical Volume
Alert If

Select from the drop-down menu when an alert is generated.

  • Exists: An alert is generated if the named instance exists
  • Does Not Exist: An alert is generated if the named instance does not exist
  • Criteria Triggers: An alert is generated if the remaining criteria are met

Instance section

This section is used to identify the actual instance of the selected Monitor Type for this rule.

Logical Volume/Physical Volume/Volume Group

Use the first drop down menu to select whether the Logical Volume, Physical Volume or Volume Group is defined by the use of wildcards @*' and '?' or by Regular Expression (Regex). Use the second drop-down menu to select the required instance or enter the full path to an entry of your choice.

Trigger section

This section is used to define the Performance Type and Trigger Value for the rule criteria.

Performance Type

From the drop-down menu, select the performance type by which the Logical Volume, Physical Volume or Volume Group is measured. The selections available in the drop-down menu are dependent on the Monitor Type for which the criteria is being set.

Trigger Value

Specify the comparator (equals, greater than, less than, etc.) and enter the value threshold which if met or breached, depending on the comparator used, triggers an alert.

NOTE: For Physical and Logical Volume Monitor Types, a Regex can also be used as a comparator.
Perform Actions For

If the criteria is set to perform actions for the first triggered instance, any resulting alert contains a summary of the instances that breached the criteria threshold. If it is set to perform actions for all triggered instances, then an alert is raised for each instance containing only details of that particular instance.

Criteria Alert Details section

Fields in this section define alert settings that override the settings made on the Alert page at Rule level. This provides a criteria specific alert message to be generated.

Override Rule Default

Click Override Rule Default to specify that the entries on this page override the default Alert page settings at Rule level. From the drop-down menu, select the alert warning level.

Alert Text

Enter the actual text of the alert or use the available Substitution Variables to construct the message text of the alert.

TIP: When Substitution Variables are used, click to display a list of textual and numeric parameters that can be used to amend the actual Substitution Variable value.
Alert Example

Displays an example of how the Alert Text will read using the selected Substitution Variables and user-entered text.

SLA Statistic section

Fields in this section are used to indicate that the criteria for this rule are used to determine performance against Service Level Agreements (SLA).

SLA Statistic

Click the SLA Statistic field so that it is enabled. The SLA flag is measured against the specific criteria defined for this rule.

TIP: If multiple SLA flags are being set for different criteria and/or monitors, we recommend that a Send Enterprise Console alert action is created to determine which of the SLA criteria has failed.
NOTE: SLA Statistic checking is not affected by the suspension of the rule, (SLA data is still gathered even if the rule is suspended) but is dependent on the time period when the rule is active (SLA data is not gathered outside the times when the rule is active).

 

We recommend that when creating SLA flags within rules, that all SLA criteria are kept together in the same rule that use the ‘Perform Actions For Each Criteria That Triggers option, otherwise SLA failures may or may not be indicated correctly.

 

System performance against the specified SLA flags can then be viewed on the SLA Statistics report (automatically included as a Report Template within Advanced Reporting Suite) for this system.

Ignore Instances section

This field is used to define any instances that can be ignored by the rule.

Click Add to open the Add Instance dialog. Type the name of the instance to be ignored and click OK. Wildcards '*' and '?' can be used to create the entry. Multiple ignored instances can be added to a single rule.

Testing

Once the criteria has been set, click Test to ensure that the returned results are the same as would be expected if the rule was live.

Click OK to define the entered parameters as criteria for this rule.

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