[T Series]A Mac OS Inherent Mechanism Defect Led to a Failure to Update Capacity Information After a LUN Expansion

Publication Date:  2012-07-19 Views:  112 Downloads:  0
Issue Description

Product and version information:

  • S5500T V100R001 V100R002
  • S5600T V100R001 V100R002
  • S5800T V100R001 V100R002
  • S6800T V100R001 V100R002
  • Application server operating system: Mac os X server 10.5.4 or 10.6.7
  • HBA: ATTO Celerity FC-42ES or QLogic QLE2462

Procedure:
1.Set up a connection between the host and the storage array.
2.Log in to the storage array management system. Create LUNs and map them to the host. Log in to the host. All mapped LUNs can be discovered.
3.On the storage array management system, expand the LUN.
4.After a successful LUN expansion, run the diskutil list command on the host. The displayed capacity was still the same as that before the LUN was expanded.
5.The capacity was displayed normally after the host was restarted.

Alarm Information
None
Handling Process
Expand the LUN and restart the host.
Root Cause
Apple hosts do not provide any interface for updating the capacity of external storage arrays or disks. The HBA did not report the updated capacity information to the host operating system after the HBA obtained the information.
Suggestions

1.Avoid online LUN expansion if possible. If it is absolutely necessary to perform an online LUN expansion, restart the host after the operation.
2.Use the offline expansion method instead, that is, delete all LUN mappings, and map them to the host again after they have been expanded.

We ran the same test on peer vendors' storage arrays, and the same symptom occurred.

END