After you create your LUNs, you can manage them in a number of ways. For example, you can control LUN availability, unmap a LUN from an igroup, delete a LUN, and increase the LUN size.
Selective LUN Map
Selective LUN Map (SLM) reduces the number of paths from the host to the LUN. With SLM, when a new LUN map is created, the LUN is accessible only through paths on the node owning the LUN and its HA partner.
Considerations for transitioning SAN configurations
In a SAN environment, a disruption in service is required during the transition of a 7-Mode volume to clustered Data ONTAP. You need to shut down your hosts to complete the transition. After transition, you must update your host configurations before you can begin serving data in clustered Data ONTAP
Decreasing the size of a LUN
Before you decrease the size of a LUN, the host needs to migrate the blocks containing the LUN data into the boundary of the smaller LUN size. You should use a tool such as SnapDrive for Windows to ensure that the LUN is properly decreased without truncating blocks containing LUN data. Manually decreasing the size of your LUN is not recommended.
You can move a LUN across volumes within a Storage Virtual Machine (SVM), but you cannot move a LUN across SVMs. LUNs moved across volumes within the SVM are moved immediately and without loss of connectivity.
You can delete a LUN from a Storage Virtual Machine (SVM) if you no longer need the LUN. If you create a LUN from a file, you cannot remove the file while the LUN is linked to it. You must first delete the LUN.
Examining configured and used space of a LUN
Knowing the configured space and actual space used for your LUNs can help you determine the amount of space that can be reclaimed when doing space reclamation, the amount of reserved space that contains data, and the total configured size versus the actual size used for a LUN.
I/O misalignments might occur on properly aligned LUNs
Data ONTAP might report I/O misalignments on properly aligned LUNs. In general, these misalignment warnings can be disregarded as long as you are confident that your LUN is properly provisioned and your partitioning table is correct.
Tools available to monitor your LUNs effectively
You must monitor your LUNs effectively to ensure you do not run out of space and cause a service disruption. System Manager and OnCommand Insight are additional tools that you can use to help you effectively monitor the space available to your LUNs.
Ways to address issues with LUNs go offline
When no space is available for writes, LUNs go offline to preserve data integrity. LUNs can run out of space and go offline for various reasons, and there are several ways you can address the issue.
What host-side space management is
In a thinly provisioned environment, host side space management completes the process of managing space from the storage system that has been freed in the host file system.