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Managing LUNs for FC and iSCSi

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.

  • Increasing the size of a LUN
    Beginning in ONTAP 9.5, you can grow your LUN up to 16 TB regardless of its original size.
  • 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.
  • Moving LUNs
    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 an SVM are moved immediately and without loss of connectivity.
  • Deleting LUNs
    You can delete a LUN from a storage virtual machine (SVM) if you no longer need the LUN.
  • Considerations for copying LUNs
    There are considerations you should be aware of when copying a LUN.
  • Recommended volume and file or LUN configuration combinations
    There are specific combinations of FlexVol volume and file or LUN configurations you can use, depending on your application and administration requirements. Understanding the benefits and costs of these combinations can help you determine the right volume and LUN configuration combination for your environment.
  • 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.
  • Ways to limit LUN access with port sets and igroups
    In addition to using Selective LUN Map (SLM), you can limit access to your LUNs through igroups and port sets.
  • 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
    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.
  • Controlling and monitoring I/O performance to LUNs by using Storage QoS
    You can control input/output (I/O) performance to LUNs by assigning LUNs to Storage QoS policy groups. You might control I/O performance to ensure that workloads achieve specific performance objectives or to throttle a workload that negatively impacts other workloads.
  • Tools available to effectively monitor your LUNs
    Tools are available to help you effectively monitor your LUNs and avoid running out of space.
  • Ways to address issues when 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.