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    > Newsletter > July 2006 > Ask Al
 
   
 

Ask Al

When I examine my system logs for my Enterprise 250 I see repeated time out errors for “/pci@1f,4000/scsi@3/sd@6,0”. Everything seems to be operating ok. What is the message telling me?

Answer:
The On-Line! Detective has a module that makes sense of Sun’s methodology for mapping devices. This module also includes a table that will show you which device is faulty.

Error messages, system logs and system status commands often identify devices by their device paths. It is important to be able to interpret device path so an actual physical slot location or the correct faulty device can be correctly identified. The Detective has a new Device Mapping Module that will help in this task. This module will guide the user in identifying slot numbers from a device's fully qualified physical path name, identifying and managing I/O devices and locate fault.

Below is a excerpt from the Controller Mapping module:

The physical address represents a physical characteristic that is unique to the device. Examples of physical addresses include the bus address and the slot number. The slot number indicates where the device is installed.

A physical device is referenced by the agent ID (AID node identifier). In the device path beginning with ssm@0,0 the first number, 0, is the node ID.

All hardware devices in a system are identified with a uniquely qualified full device name, also called the physical device name. The full device pathname identifies a device in terms of its location in the device tree by identifying a series of node names separated by slashes, with the root (top level of the path) indicated by a leading slash. The Physical device files can be found in the /devices directory. Each node name in the device pathname has the following form:

driver-name@unit-address:device arguments.
Key:
driver-name - identifies the device name;
@unit-address - is the physical address of the device in the address space of the parent;
device arguments - defines additional information regarding the device software.

Matching the devices to the physical path's driver names will help identify the type of device. The table below provides the descriptions of some commonly used device driver prefixes and their descriptions:

 
Device Driver Prefix Description
Fas Fast/wide SCSI controller
hme Fast (10/100 Mb/sec) Ethernet
isp Differential SCSI controllers and the SunSwift card
glm UltraSCSI controllers
scsi Small Computer Serial Interface (SCSI) devices
sf soc+ or socal Fiber Channel Arbitrated Loop (FCAL)
soc SPARC Storage Array (SSA) controllers
socal soc SPARC Storage Array (SSA) controllers

Device Mapping
The physical address represents a physical characteristic that is unique to the device. Examples of physical addresses include the bus address and the slot number. The slot number indicates where the device is installed. You reference a physical device by the node identifier agent ID (AID). The AID range will vary depending of the system. The AID is usually in hexadecimal notation (0 to 1f in). In the device path beginning with ssm@0,0 the first number, 0, is the node ID.

Below is an example of a device path from an Enterprise 250.

/pci@1f,4000/scsi@3

This device path references the disk controller built onto the system board that controls the six internal disk slots. The device path /pci@1f,4000/scsi@3 also references the controller built onto the system board for the internal CD-ROM or tape drive, as well as the onboard SCSI port on the system board (See Enterprise 250 Device mapping table below).

Enterprise 250 Device Mapping
PCI Slot/Device Device Path
PCI Slot #0 /pci@1f,4000/device@5
PCI Slot #1 /pci@1f,4000/device@4
PCI Slot #2 /pci@1f,4000/device@2
PCI Slot #3 /pci@1f,2000/device@1
Internal Disk Slot #0 /pci@1f,4000/scsi@3/sd@0
Internal Disk Slot #1 /pci@1f,4000/scsi@3/sd@8
Internal Disk Slot #2 /pci@1f,4000/scsi@3/sd@9
Internal Disk Slot #3 /pci@1f,4000/scsi@3/sd@a
Internal Disk Slot #4 /pci@1f,4000/scsi@3/sd@b
Internal Disk Slot #5 /pci@1f,4000/scsi@3/sd@c
Internal CD-ROM /pci@1f,4000/scsi@3/sd@6,0
External SCSI Port /pci@1f,4000/scsi@3,1/device

Looking at the table above repeated time out errors for /pci@1f,4000/scsi@3/sd@6,0 looks like a problem with the CDROM. The Device Mapping complete module can be found as one of the Related Links items on the left hand menu. Simply click on any system, navigate to the Device mapping option under the related links topic and select the Controller Mapping Module.