Powering off and on an iSCSI Interface Module Resulted In a Failure of the UltraPath to Detect an Existing LUN

Publication Date:  2012-07-19 Views:  135 Downloads:  0
Issue Description
Product and version information:
S5500T V100R001 V100R002
S5600T V100R001 V100R002
S5800T V100R001 V100R002
S6800T V100R001 V100R002

Symptom:

Application server operating system: Windows Server 2003 Enterprise X64 Edition
We mapped two LUNs to the host, and could view two virtual LUNs and four physical LUNs on the UltraPath management interface.
We powered off and on the iSCSI interface module on controller A twice.

 Then on the UltraPath management interface, we saw only one virtual LUN instead of two.
In Computer Management > Device Manager shown in Figure1, we also saw four physical LUNs and only one virtual LUN.
Figure 1 Device Manager

  • We scanned for LUNs in Disk Management several times, and only one LUN was displayed instead of two as shown in Figure2

Figure 2 Disk Management

Alarm Information
None
Handling Process
1.Delete manually the abnormal mapping from the storage device.
2.Scan for devices on the host and ensure that corresponding physical disks are deleted.
3.Add a LUN mapping again. The system automatically generates physical disks and a corresponding virtual disk.
Root Cause
The UltraPath currently uses the Microsoft MultiPath IO (MPIO) design structure. The MPIO structure may fail to update disk information when handling reported disks and deleting disks. The MPIO structure may consider a newly reported disk as an existing disk and add it to the same virtual disk group. The result in the preceding example was due to this MPIO structure defect. There is a possibility that this problem occurs.
Suggestions
Do not power on an interface module immediately after it is powered off. Observe disk status in Device Manager on the host. Power on the iSCSI interface module after the disks in Device Manager have been deleted.

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