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Resolve the S5600T remote LUN copy fault

Publication Date:  2012-11-05 Views:  17 Downloads:  0
Issue Description
A university’s data center deployed the remote disaster recovery, and it took the LUN copy function between the Huawei Symantec storage S5600T and the S5500T array, the transmit medium was a Gigabit metropolitan area network. When deploying the full LUN copy, the “well status” of the corresponding LUN copy on the ISM interface displayed as “fault”.
Alarm Information
Handling Process
1. Upload the “iperf linux” to the “/tmp” of the S5600T and S5500T respectively via the tool “SSH Secure”.
2. Make the “iperf” be available to execute in the system of S5600T or S5500T.
3. Login in the S5600T and S5500T by the “developer” user, execute “./iperf -s” in the S5600T.
4. Execute “./iperf –c  -f K –i 2 –w 300k –t 36” in the S5500T, and obtain the bandwidth picture as follow, it shows only there only be 296Kbytes/sec, it’s far less than the requirement of the LUN copy, which leads the error of the LUN copy.

5. Adjust the limitation of the network bandwidth, and test it as follow:

The bandwidth can reach to 78.6Mbits/sec.
6. During the test, we can check the traffic of the network card via the command “watch”.

7. Deploy the full LUN copy manually at the source port, the status displays as follow:

Root Cause
1. Login in the ISM, and check the LUN’s status, and it displays as “normal”.
2. Login in the array where the object is, check the array’s status on the ISM, it also displays as “normal”.
3. Check the resource status of the master array, the capacity is enough, and the resource LUN’s status is still “normal”.
4. Check the link between the source and the objective array iscsi, they are all “normal”.
5. Adopt the “telnet    3260”, all the link ports have signal output, this proves the 3260 port hasn’t been shielded by the firewall.
6. Tentatively, we confirm it caused by the shortage of link bandwidth among the arrays.

1. Through the iscsi link, deploy the functions of the IP SAN, LUN copy, and remote copy, i.e. we must pay attention to the network bandwidth.
2. To obtain the performance of access link between the client and the server, we can take this tool too.
3. We can test the network link bandwidth by the “iperf-all” tool, and it can supply as a quantized tool for applications, and is valuable for the storage and server.

Introduce the Iperf
Iperf is a tool for testing the network’s performance. It can test the quality of the TCP and UDP bandwidth, the maximum TCP bandwidth, it contains lots of parameters and UDP characters, and it can report bandwidth, delay jittering and package dropping out. There are binary system versions of the Iperf for use both in the linux and windows platforms.
The method to use Iperf and the parameters instruction:
-s, start as the “server” mode, e.g.: iperf-s. The server is the data’s receiving port.
-c, the host starts as the “client” mode, host is the address of the server port, e.g.: iperf-c, client is the data’s sending port.
For detail usage, please refer to the readme of the tool set.