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How to test the transmission speed from the CNA to the IPSAN?

Publication Date:  2012-11-21 Views:  31 Downloads:  0
Issue Description
Test the transmission speed from the CNA to the IPSAN can be used for many objects, such as:
1. Calculate the time spending in making the virtual machine’s volume on the IPSAN DD to the CNA;
2. According to the speed to estimate whether the network from the CNA to the IPSAN is normal.
However, how to test the transmission speed from the CNA to the IPSAN?

Alarm Information
Handling Process
1. Login in a random CNA node via the putty.
2. Execute “lsscsi | grep -i updisk” to check the CNA’s local volume.
3. Execute the command “dd if=/dev/sdc of=/dev/null bs=1M count=1000” to test.
The outcome of the command is displayed as followed:
1000+0 records in
1000+0 records out
1048576000bytes (1.0GB)copied,18.6s , 56MB/s
The above command denotes that copy 1G data to the IPSAN, and the outcome will return back the transmission speed and time. Where, the “sdc” is the second volume it will find out.
The instruction of the parameters:
(1) dd: use the appointed extent to copy a file, and implement the appointed transform while copying.
(2) if=file name: input the file name, it’s standard input by default, i.e. appoint the source file.
< if=input file >
(3) of=file name: output the file name, it’s standard output by default, i.e. appoint the target file. < of=output file >
(4) bs=the capacity of the extent, there it’s set as 1M.
(5) count=the number of the extents, there is 1000, i.e. 1G
(6) dev/null ------it’s a empty device, it still named bit bucket, any output write in it will be discarded.
(7) /dev/sdc: it’s a partition of the CNA.

Root Cause
1. The normal speed must be over 50M/s, there may be abnormal condition in the network while the speed is below this value, we can check if there is alarm on the IPSAN or check if the negotiation speed of the IPSAN port is 1GM on the switch.
2. We suggest the value of the “count” shouldn’t be too big, or once there is some problem in the network, the time spend in implementing the command will be rather long. If the condition is normal, generally, we take the “count” as 1000, and the corresponding implementation time is about 20 seconds.