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For a couple of threads now the support team has asked to "send traces" of failures. Could we get instructions on how to collect these traces? Packet sniffing or something more elegant?

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Guest Ted Richardson

Collecting traces for troubleshooting iSCSI issues is very simple using the terminal window and the tcpdump command that comes with OS X.

The command requires using sudo, which means that you will need to provide an administrative password to run the command. This command does not make any changes to the OS, so it is safe to run.

Using the syntax below will, however, capture all of the traffic between your workstation and the target machine so if there is other (non-iSCSI) traffic between these two devices, please disable these services if possible. The use of chap security may hide some of the important troubleshooting data. Also, this capture may reveal values of chap secrets, so please disable chap before running this command.

Finally, running this command while reading and/or writing actual data to the iSCSI target can create a very large capture file. Please only use this technique to help diagnose the initial connection to iSCSI storage.

Here are the steps:

1) Run the following command:

sudo tcpdump -i {interface} -n -s 0 -w {output file} host {ip addr or hostname of target}

Note:

{interface}
is the ethernet interface that the OS X machine uses to talk to the target. Use the ifconfig command to determine the correct interface. This should be something like en0 or en1.

{output file}
is the file name for the captured traffic. This is the file that you will send to us when the capture is complete.

{ip addr or hostname}
is the address or hostname of the iSCSI target device. This filters the capture to just traffic to and from the target.

for example:

sudo tcpdump -i en1 -n -s 0 -w target.cap host 192.168.1.250

2) Attempt to connect to your target using the globalSAN initiator. Wait until error or problem occurs.

3) Use <Control>-c to end the tcpdump command.

4) Send the resulting output file to us at iscsi@studionetworksolutions.com.

Thanks,

Ted

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