Application Servers Unable to Recognize Mapped File Systems Due to Offline Volume Resource

Publication Date:  2012-07-22 Views:  80 Downloads:  0
Issue Description

A project employs two DELL 2950 servers to provide the Microsoft cluster service (MSCS) for Exchange mail service, and the previous cluster service employs a storage device from the vendor H and uses iSCSI links for communication. The previous storage device mapped three LUNs to the cluster, with capacity of 500 MB, 500 MB and 1.4 TB respectively.

After stopping services, both the previous storage device and the S5300 are mapped to the VIS, and the data migration is completed by using the previous storage device as the data source to create a mirror volume. After completing the migration, the VIS is then powered off. The cluster is installed with the UltraPath and connects to the S5300 using the multipath networking. When one of the ASs of the cluster is started, the OS of the AS recognizes two LUNs with each capacity of 500 MB, but fails to recognize the file system of the LUN whose capacity is 1.4 TB.

Product and version information:
  • S5000 series
  • The operating system of the AS node is Windows Server 2003
The networking of the MSCS is as shown inFigure 1.
Figure 1 MSCS networking

Alarm Information
None
Handling Process
  1. Remap the S5300 to one of the ASs in the cluster, and wait until the quorum disk can be successfully recognized.
  2. Place the volume resource online in the cluster, and wait until the volume can be successfully recognized.
  3. Start two cluster servers and install the UltraPath on both servers to perform the link switchover test. If the test succeeds, the fault is removed.
Root Cause
  1. The problem persists after uninstalling the UltraPath on the AS and using a single link to connect to the S5300.
  2. However, it is found that three LUNs of the S5300 can be successfully recognized after mapping them to another AS.

Conclusion:

  • The AS in the cluster fails to recognize the mapped file system when the volume resource is not placed online in the cluster service.
Suggestions

A cluster is a collection of computers that are running the same software and are interconnected to present as a virtual host to provide service for clients and applications. All the computers in the cluster are physically interconnected through cables and are virtually interconnected through a cluster software, which enables fault tolerance and load balancing that cannot be implemented by a single computer.

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