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Rescans Might Cause CD-ROM Drives Attached to vmhbas to Become Inaccessible from the Service Console

Details

Performing a rescan removes CD-ROM drives attached to vmhbas.  Vmhbas are storage host bus adapters (HBAs) that are registered with the VMkernel. Vmhbas include SCSI and SATA HBAs, but not USB or IDE HBAs.
 
This type of rescan occurs when you request a Storage Rescan operation from the VI Client, or when you use the command-line utility esxcfg-rescan.  Some third-party management agents also perform this operation.

Solution

A rescan removes the CD-ROM drives from the service console kernel configuration and does not restore the configuration, which leaves the devices inaccessible from the service console.

As a workaround, you can manually add the missing CD-ROM drive to the service console after the rescan is finished.

To do this, complete the following steps:

  1. Examine the output of esxcfg-mpath -l for the CD-ROM drives. 

    Notice the vmhba and the designation of the device. 

    For example:

    CD-ROM Drive vmhba32:0:0 /dev/scd0 (0MB) has 1 path and policy of Fixed Local 0:31.2 vmhba32:0:0 On active preferred

    Here, vmhba32 has a CD-ROM drive with the ID:LUN of 0:0.

  2. Map the named vmhba number to the service console's SCSI HBA number by examining the output of cat /proc/vmware/vmkstor.

    For example:

    VMnix name   VMkernel name   Owner
    scsi1        vmhba32         VMKernel


    Here, the CD-ROM device belongs to vmhba32, which maps to SCSI HBA 1.

  3. Restore the CD-ROM drive to the service console, using the following command:

    echo 'scsi add-single-device <SCSI HBA number from step 2> 0 <ID from step 1> <LUN from step 1>' > /proc/scsi/scsi

    For example:

    # echo 'scsi add-single-device 1 0 0 0' > /proc/scsi/scsi

Note: This problem occurs each time you rescan your storage devices and requires that you perform the workaround procedure afterwards.

Based on VMware KB 1006943


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