[Info-vax] USB disk enclosures

[Steven Schweda]

> My intent was that perhaps others might like to know of a
> USB adapter that "appeared" to work with VMS.

   Why?  For adapter suggestions, see
SYS$SYSTEM:SYS$CONFIG.DAT.  This has been discussed in the
past.

> >> Note, I don't do USB stuff,
> >
> >    So the value of your advice may be how great, exactly?
> 
> Probably as good, or bad, as anyone else's [...]

   No, probably not.

> Yep.  Just what I'd expect from some "quick and dirty"
> implementation.

   What, exactly, is "quick and dirty" about using a USB
serial number to identify a storage device?

   I'm too far from my VMS systems to try much, but my dim
recollection is that removing and reconnecting a USB Flash
EEPROM storage gizmo tends to get the same VMS device name
each time.

> Do USB devices even have the concept of unit numbers?

   I gather that some device classes have serial numbers:

http://www.usb.org/developers/docs/devclass_docs/usbmassbulk_10.pdf

See section 4.1.1, "Serial Number":

      The iSerialNumber field shall be set to the index of
      the string descriptor that contains the serial number. 
      The serial number shall contain at least 12 valid
      digits, represented as a UNICODE string.  The last 12
      digits of the serial number shall be unique to each USB
      idVendor and idProduct pair.

   A Mac "System Information" report shows data like the
following for two identical-looking (8GB) gizmos from Micro
Center:

  Product ID:   0x4100
  Vendor ID:    0x13fe  (Phison Electronics Corp.)
  Version:      1.00
  Serial Number:        07013613CEB2F919
[...]

  Product ID:   0x4100
  Vendor ID:    0x13fe  (Phison Electronics Corp.)
  Version:      1.00
  Serial Number:        07013614EAB2F950
[...]

   I know nothing, but I assumed that someone (UCM) was
keeping track of those serial numbers, and that's how one
gizmo could get the same VMS device name on different
occasions.

   I don't recall seeing any actual info from the problem
gizmos in this case, but my current guess is that they fail
to meet this requirement, or at least the USB serial number
is associated with the USB-SATA adapter itself, and not with
the SATA device, which might be enough to fool the VMS UCM.