Reclaiming Space of Unused LUNs

Identifying Unmapped (Orphans) LUNs

Over time, as servers connected to a SAN get decommissioned, administrators find an increasing number of unmapped LUNs, or volumes that are no longer used by any server. These LUNs, while unused, still occupy disk space in the disk array. Being able to identify such unmapped LUNs and reclaim the disk space uselessly consumed by these LUNs will help administrators avoid unnecessary upgrades and extensions of their disk arrays.

To list the LUNs in a disk array that are not mapped to any server and therefore safe to remove, right-click the disk array icon > KM Commands > Reporting > LUNs Mapping Table... . Whether a LUN is actually mapped or not is also shown in the infobox of each volume instance.

IBOX_Mapped_LUN

LUN Properties - Infobox tab

Identifying Unused LUNs

When a server is decommissioned or reconfigured, its associated LUNs can stay mapped preventing storage administrator from accurately identifying unused LUNs. Since the KM monitors permanently the traffic on each LUN, it becomes easy to detect LUNs for which the activity is null.

1.	Create a PATROL Query in the PATROL Console to show the value of the TimeSinceLastActivity parameter of the SEN_EMC_VOLUME_CLAR or SEN_EMC_VOLUME_SYMM application class; In the main menu bar, click Action > New Query…

QUERY_Unused_LUNs

PATROL Query – General Tab

2.	Enter the Query name (example: Unused LUNs)

3.	Enter the Query description (optional)

4.	In the Query Results Filter section, select Show Selected Objects and check the Parameters box

5.	In the Additional Filtering, select the Application Class level filtering and the Enable Parameter level filtering options

6.	Open the Application Class tab

QUERY_Unused_LUNs_Class

PATROL Query – Application Class Tab

7.	In the Pattern Matching section, select Like and type SEN_EMC_VOLUME_CLAR (or SEN_EMC_VOLUME_SYMM)

8.	Open the Parameter tab

QUERY_Unused_LUNs_Param

PATROL Query – Parameter Tab

9.	In the Pattern Matching section, select Like and type TimeSinceLastActivity

10.	Click OK to display a list of the monitored LUNs and their respective number of days since when the KM has not recorded any activity.

QUERY_Unused_LUNs_Results

PATROL Query – Results

The value collected for this parameter upon the first collect reflects the number of days since any activity occurred on the volume for the time observed by the KM, i.e. this first collected metric might not reflect the actual absence of activity on the volume.