A new version of Microsoft's Storport storage driver fixes a number of seemingly unrelated problems on SANs that use removable storage devices connected through host bus adapters (HBAs).
Although the symptoms are diverse, they all have the same cause. Essentially, the previous version of the Storport driver didn't always work properly when a removable storage device that used an HBA was replaced (or removed). Depending on the circumstances, this could generate a variety of strange results, including the dreaded blue-screen crash.
The bug can also produce other puzzling symptoms. For example, if you remove a drive cable from an HBA in a Microsoft MultiPath I/O (MPIO) setup, the system may not clean up the LUNs. Thus, if Disk A is identified as Target 1, LUN 1, and it is replaced by Disk B, Disk B will also be identified at Target 1, LUN 1. When a later operation tries to access the no-longer-existing path, the computer may hang.
The bug can also produce a memory leak when an inquiry operation for disk information (page 0x83 data) causes a new allocation to be created. The allocation isn't freed and 512 bytes per inquiry remains tied up. If this goes on long enough, it will exhaust non-paged pool memory and you will get error messages or the computer will hang.
Microsoft fixed the problem by releasing a new version of the Storport driver (version 5.2.3790.2630). It describes the fixin full detail on its Web site.
About the author: Rick Cook has been writing about mass storage since the days when the term often meant an 80K floppy disk. Today he specializes in writing about issues related to storage and storage management.
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