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TechNote: How to Read an Enterprise Server Device Path

A frequent question when troubleshooting Ultra Enterprise servers is how to read the hardware device paths and determine to what board it is referring. For example, this is a device path from an Ultra Enterprise 3000 server:

/sbus@3,0/SUNW,fas@3,0/sd@0,0

Using the tables below, it can be seen that sbus@3,0 corresponds to the I/O board in slot 1, located on the rear of the system. Using the second table, it can be seen that SUNW,fas@3,0 corresponds to the onboard fast/wide SCSI controller of this same board. I/O boards are basically split in half with each half controlled by a Psycho or SysI/O chip (A or B).

The next portion of the device path, sd@0,0, corresponds to the SCSI disk (sd) set to target id 0. In this case it is an internal disk as only internal disks should be controlled by the onboard SCSI controller of the I/O board in slot 1 on an Ultra Enterprise 3000.

Another example:

/sbus@5,0/scsi@2,0/st@5,0

This device path corresponds to an I/O board in slot 2 in the front of a UE server (sbus@5), and a SCSI controller card in slot 2 on the I/O board (scsi@2). The st@5 is a SCSI tape (st) drive at target id 5 attached to this controller.

A more complicated example:

/sbus@6,0/SUNW,socal@d,0/sf@0,0/ssd@2200002136bcd49,0 (ssd27)

This device path corresponds to an I/O board in slot 3 of a UE server (sbus@6), the onboard socal controller (socal@d), and finally the GBIC port on the right (sf@0). The ssd@2200002136bcd49,0 (ssd27) represents a a disk in an A5x00 array. The long number after the '@' sign is the "world wide number" (unique) of this particular disk.

            Board Slot - Sbus Slot Assignments

         |--------------------------------------| 
         |        Front     |        Rear       |
         |--------------------------------------|
         | Sbus@  |  Sbus@  |  Sbus@  |  Sbus@  |
  Slot#  |--------------------------------------|Slot#
   0     |  0     |    1    |    2    |    3    |1
         |--------------------------------------|
   2     |  4     |    5    |    6    |    7    |3
         |--------------------------------------|      
   4     |  8     |    9    |    A    |    B    |5
         |--------------------------------------|
   6     |  C     |    D    |    E    |    F    |7
         |--------------------------------------|
   8     |  10    |    11   |    12   |    13   |9
         |--------------------------------------|
   10    |  14    |    15   |    16   |    17   |11
         |--------------------------------------|      
   12    |  18    |    19   |    1A   |    1B   |13
         |--------------------------------------|
   14    |  1C    |    1D   |    1E   |    1F   |15
         ----------------------------------------

This table displays which onboard controller or slot is controlled by which SysI/O chip.


            Onboard Slot Assignments

  |------------------------------------------|
  |        Front        |         Rear       |
  |------------------------------------------|
  |  SysioA  |  SysioB  |  SysioA  |  SysioB |
  |------------------------------------------|
  |  soc@d   |  fas@3   |  soc@d   |  fas@3  |
  |  sbus@1  |  hme@3   |  sbus@1  |  hme@3  |  
  |  sbus@2  |  sbus@0  |  sbus@2  |  sbus@0 |
  |------------------------------------------|

Note: When dealing with an soc+ (socal) I/O board, sf@0 is the GBIC port on the right and sf@1 is the GBIC port on the left.



 

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