[T Series]VXVM Failed to Obtain and Update LUN Status Due to a LUN Failure

Publication Date:  2012-07-19 Views:  144 Downloads:  0
Issue Description
Product and version information:
S5500T V100R001 V100R002
S5600T V100R001 V100R002
S5800T V100R001 V100R002
S6800T V100R001 V100R002
Application server operating system: Microsoft Windows Server 2008 Enterprise X64 Edition SP2
Cluster software: Microsoft WSFC

Scenario:
 

1.The storage array was directly connected to the host through two redundant paths. A LUN was mapped to the host.
 

2.The LUN was successfully partitioned and was allocated with drive letters. An NTFS file system was created on the formatted LUN.
 

3.The host performed read/write operations on the LUN and the LUN failed. In such a case, the following two situations may occur: VXVM could not update LUN status in a timely manner. VXVM could not update the partitions created on the LUN in a timely manner.
 

4.Symptoms are: Files could still be copied to the partitions created on the failed LUN.
 

5.These files were stored on the host cache. However, if the host powered off unexpectedly, the file data was lost.

Cluster software version: native version 6.0
Alarm Information
None
Handling Process
Recover the failed LUN and then data in the host cache will be written to the disks correctly.
Root Cause

The service data was written to the cache of the Storage Foundation (SF) management, not to the storage array directly.

The operating system did not report the error upon the LUN failure, and VXVM did not cope with the LUN status. Therefore, the data was still copied to the partitions created on the failed LUN.

The data was not written to the storage array until the memory allocated to SF was used out. The storage array then detected the LUN failure and reported it to the operating system which reported it to VXVM. VXVM then updated the status of the LUN and its partitions.

Suggestions

If it is absolutely necessary to use Huawei Symantec SF for managing disks on Windows, users must be notified of the risks described in this case.

SF is an aggregate of the storage management software provided by Huawei Symantec to offer a complete solution of managing heterogeneous storage arrays online. SF includes VXVM and VXFS.

END