Storage Area Network (SAN) Device Ping

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This function can be equated with a standard TCP/IP ping. It is used to both determine connectivity to a device and to report the amount of milliseconds it takes for a packet of data to get to the device and be acknowledged by it.

Syntax

smartmon-ux -fcping PortWWN LUN_Number [Attempts]

The LUN_Number would typically be zero for standard disks and tapes. It is quite common to be non-zero for logical disks created by external RAID subsystems.

The PortWWN corresponds to the fibre channel port WWN for the selected device. This information can be obtained by a variety of methods, including:

•	Running smartmon-ux -fc which will dump all port and WWN info for the devices it can see

•	Your HBA management software

•	Your operating system's registry or boot logs (i.e., /vary/log/messages or dmesg)

The optional attempts field is used to tell the program how many attempts it should make. If you enter zero, it will send data indefinitely, or until you abort or kill the program.

Example

D:\TEST>smartmon-ux -fcping 22:00:00:20:37:E6:0A:38 0

Port 22:00:00:20:37:E6:0A:38 replies in 0.010s as SEAGATE ST336605FC

Port 22:00:00:20:37:E6:0A:38 replies in 0.000s as SEAGATE ST336605FC

3 successful and 0 unsuccessful pings.

Average ping time: 0.003s.

D:\TEST>smartmon-ux -fcping 22:00:00:20:37:E6:0C:84 0 10

Port 22:00:00:20:37:E6:0C:84 replies in 0.000s as SEAGATE ST336605FC

Port 22:00:00:20:37:E6:0C:84 replies in 3.044s as SEAGATE ST336605FC

Port 22:00:00:20:37:E6:0C:84 replies in 0.000s as SEAGATE ST336605FC

10 successful and 0 unsuccessful pings.

Average ping time: 0.304s.

You'll note that the Windows machine above is not very consistent in performance. There was a 3-second delay on the 5th attempt. This is something that the system administrator may wish to investigate.

The following example shows what will happen if you attempt to ping a non-existent device.

D:\TEST>smartmon-ux -fcping 22:00:00:20:37:E6:0C:99 0 10

Could not find path to LUN #0 at port WWN 22:00:00:20:37:E6:0C:99 from:

- Adapter Port: QLogic Corporation QLA2340 20:00:00:E0:8B:0F:1D:3D

Finally, we're pinging the disk subsystem from the SPARCStation. You will note that the operating system does not affect the syntax of the results.

# ./smartmon-ux -fcping 21:00:00:20:37:E6:06:31 0 10

Port 21:00:00:20:37:E6:06:31 replies in 0.010s as SEAGATE ST336605FC

10 successful and 0 unsuccessful pings.

Average ping time: 0.010s.

Additional Information

A few things to know about this feature.

•	The granularity of the ping is measured and reported in milliseconds.

•	The program sleeps for 1000 milliseconds (1 second) between each ping attempt, whether successful or unsuccessful.

•	SMARTMon-UX will not let you ping a port name that is not known to the HBA. This is by design, as we have seen the Q-Logic library lock up on LINUX in testing when we attempted to ping a device which does not exist.

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All of this information is obtained by communicating directly with your HBA through the SNIA API library. On more than one occasion we have seen incorrect results returned by HBAs. Some times updating the HBA firmware and drivers to the latest release fixed the problem. Other times the bad data is unique to a particular HBA model, firmware revision, and operating system.

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We have sometimes seen that the HBA never responds, or that the program will lock up (but not your computer) when using the -fc or -fcpingcommands. This is due to bugs in the API, or not having the latest firmware and/or drivers for your HBA loaded. Please report this information both to us, and to your HBA supplier to get them resolved. Often, if you just upgrade to the most current HBA drivers then the problems and lockups go away.