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Identifying CD drives across reboots

Hello all,

I need to store some metadata about various CD drives, and have that information be accessible across reboots.  I have a few ideas but I haven't figured out the best way to handle things yet.  My current code does the following:

1) Registers with DiskArbitration for IOCDMedia events
2) When an event occurs, I grab the IOPath from the DADisk's description and match that with an io_service_t
3) I inspect the io_service_t's properties, particularly for kIOPropertySCSITaskUserClientInstanceGUID
4) I use the GUID to uniquely identify the device

Here is where I am a stuck; I would have expected that the GUID remains the same across reboots, but empirical evidence suggests this is not the case.  So I can't use the GUID as a key for drive identification.  This may be a good thing, since ROM drives may not be STUC devices and as such wouldn't have a GUID anyway.

My next idea was to use the drive's serial number via kIOPropertyProductSerialNumberKey, but while IOStorageDeviceCharacteristics.h says the key is mandatory it is missing for my drive:

    "Device Characteristics" =     {
        "BD Features" = 0;
        "CD Features" = 1791;
        "DVD Features" = 503;
        "Low Power Polling" = 1;
        "Power Off" = 0;
        "Product Name" = "DVD-R   UJ-845E";
        "Product Revision Level" = DMP2;
        "Vendor Name" = MATSHITA;
    };

So obviously this won't work either.

My third idea is to use the IOPath of the device, but is this a reliable way to uniquely identify a CD device?  I have a feeling it isn't, but I'm not quite sure. 

Is there another way to accomplish what I am trying to do?

Thanks,
Stephen
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