CD/DVD drive letter changes in Microsoft Windows after AMM reset - IBM BladeCenter H (Type 8852)

Resolving The Problem

Source

RETAIN tip: H191378

Symptom

After multiple restarts of the Advanced Management Module (AMM), the CD-ROM drive letter in Microsoft Windows may change.

Linux does not have an issue. Linux assigns the same /dev/scdX or /dev/cdromX to the USB CD-ROM, even though they will have a different USB path.

Affected configurations

The system may be any of the following IBM servers:

• BladeCenter H, type 8852

This tip is not software specific.

This tip is not option specific.

Workaround

Assign the same drive letter to each of the USB Device ID instances.

There will be only one entry but there are two opportunities to obtain a USB Device ID: Serialized and non-Serialized. The Serialized Device ID corresponds to the actual CD device. Non-Serialized Device IDs occur when a failure occurs when obtaining the attached device serial number. You will see an entry similar to the following:

The Device Instance ID can be obtained by right clicking "My Computer" then choosing "Computer Management", next selection is "Device Manager". Select the Media Drive, Right-click and open "Properties", select "Details".

To Change the Drive Letter within Microsoft Windows:

1. Log into Microsoft Windows and right click "My computer", and choose "Computer Management".
   
   
2. From "Computer Management" choose "Disk Management", select the Media Drive and change the device to the drive letter of your choice.
   

Additional information

Every time the AMM resets, Microsoft Windows always re-initializes the USB CDROM in the media tray. The USB host will request the DEVICE Descriptor and STRING descriptor to retrieve the Serial Number of the USB CDROM. The GET STRING DESCRIPTOR request may fail and Microsoft Windows will detect two different USB devices, one which has a serial number (in good case), another which has no serial number (in bad case).

The workaround alleviates the problem by assigning a non-serialized Device Instance ID and the serialized Device Instance ID with the same drive letter. Thereby, any occurrence will have the same drive letter assigned.