Skip to main content
NetApp Knowledge Base

How do lun reset and target reset commands affect SCSI-2 Reservations?

Views:
1,966
Visibility:
Public
Votes:
4
Category:
ontap-9
Specialty:
san
Last Updated:

 

Applies to

  • Data ONTAP 8
  • ONTAP 9

Answer

Background

  • An initiator sets a reservation on a LUN in order to prevent another initiator from making changes to the LUN, similar to a 'file-locking' concept.
  • SCSI reservations are always set by a host initiator, and ideally, the same initiator performs a SCSI release on the LUN in use.
  • Most LUNs are mapped to a single host, but in the case of a host cluster (e.g. VMware, SQL, Oracle), the same LUNs are mapped to multiple host nodes.
  • In some cases, it might be necessary for the host to clear a reservation that it did not initiate.
  • This is performed by running the 'lun reset' and 'target reset' SCSI commands.

 

Do you have to use a specific LUN when running the 'target reset' command?

The 'target reset' command can be run by an initiator without addressing a specific LUN, but a 'lun reset' command requires a specific LUN to be addressed.

 

Will a SCSI 'lun reset' command clear a SCSI-2 reservation?

Yes

 

Can a SCSI 'lun reset' command be run from any initiator, on any host, that has visibility to the LUN?

Yes, but the 'lun reset' command needs to be addressed to a specific LUN.

 

Will a SCSI 'lun reset' command affect any other initiators that are logged into a specific LUN?

Yes, all initiators mapped to a specific LUN will receive a LUN RESET notification.

 

Will a SCSI ' target reset' command affect all LUNs, from all initiators, that are logged into a target LUN?

The 'target reset' command on a NetApp SCSI target resets only those LUNs that are mapped to the initiator that is running.

 

Will a SCSI 'target reset' command clear SCSI-2 reservations on a mapped LUN that resides on a target?

Yes (see previous question). A SCSI-2 reservation will be cleared only on those LUNs that are reset.

 

Will a 'lun reset' or 'target reset' command affect SCSI-3 reservations?

No

 

Sign in to view the entire content of this KB article.

New to NetApp?

Learn more about our award-winning Support

NetApp provides no representations or warranties regarding the accuracy or reliability or serviceability of any information or recommendations provided in this publication or with respect to any results that may be obtained by the use of the information or observance of any recommendations provided herein. The information in this document is distributed AS IS and the use of this information or the implementation of any recommendations or techniques herein is a customer's responsibility and depends on the customer's ability to evaluate and integrate them into the customer's operational environment. This document and the information contained herein may be used solely in connection with the NetApp products discussed in this document.