Fibre Channel (SAN)

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New Contributor
Posts: 2
Registered: ‎01-05-2011

SAN-WAN Problem

My engineers have trouble running a SAN over a CWDM WAN Multiplexor link.

Setup:

NetApp MetroCluster with Fujitsu Servers connects to Brocade 300 FC switch.

The Brocade 300 FC switch connects to a Brocade certified CWDM Mulitiplexer running over

a 3km Distance Fiber optic link to a remote site wich consist of the same equipment setup.

What happens:

An normal "spinfab" test with the Brocade 300 FC switches does not show any errors.

All port statistics are clear. If the NetApp MetroCluster application is started,

tim_txcrd_z counters are increasing on all operational ports of the Brocade 300 FC switches.

If an NetApp disk scrub test is started, it takes a while (approximately 12 minutes)

and then the test is aborted.

If we eliminate the Brocade certified CWDM Multiplexer everything runs fine!

Any idea on wich parameters and on wich equipment parameters have to setted?

Thanks for any help!

Super Contributor
Posts: 635
Registered: ‎04-12-2010

Re: SAN-WAN Problem

Hello,

did you follow the NetApp recommended cabling and configuration instructions?

A MetroCluster configuration is driven by NetApp and it is important what NetApp has certified and not Brocade.

Did you change the amount of ISLs between the switches?

Are the CWDM SFPs on the same speed as the normal Longwave SFPs?

Did you change any buffer parameter?

Did you use one or two pairs of CWDM sets?

Remember everything which is not redundant is not HA.

Andreas

New Contributor
Posts: 2
Registered: ‎01-05-2011

Re: SAN-WAN Problem

Hello Andreas,

thanks for your interesting points. We doublechecked on your answers and question.

For easier reading, i just copied my answers with your text.

did you follow the NetApp recommended cabling and configuration instructions?

RE: Cabling and configuration was done according to TR3548 and instructions from NetApp-technical Engineer.

A MetroCluster configuration is driven by NetApp and it is important what NetApp has certified and not Brocade.

RE: The Answer from NetApp to the question <Can we certify our xWDM-System together with Netapp for MetroCluster-Application?>:

“ xWdms are certified by Brocade and can be used ...” “ ... But they are not tested with a Metro-Cluster”

“But there is no extra certification possible with Netapp”

Do you know a way to certify our xWDM-System at a Netapp-Lab?

Did you change the amount of ISLs between the switches?

RE: “Tests have been made with two active ISLs as well as with one active ISL-Connection”

Are the CWDM SFPs on the same speed as the normal Longwave SFPs?

RE: Yes in the 4Gig-Application every SFP used in the System were 4Gig-FC-SFPs

Did you change any buffer parameter?

RE: The Fiber-Distance was 3km and the Tests have been made with LE-Config as well as Port-Defaultconfiguration

Did you use one or two pairs of CWDM sets?

RE: One Dark fiber carrying two ISL-Connections over 2 CWDM-Channels for Metro-Cluster-Application according TR-3548

Remember everything which is not redundant is not HA.

RE: The Error-Scenario was when running “disc scrub” after about 12 minutes the system (Filer) reported excessive disk-Errors

  The Brocade-Switches reported Errors (encin, crc, bad_eof, bad_os)at the ISL-Connections as well as high tim_txcrd_z at every Port (ISL and FL-Ports)

Looking forward for your response!

Thomas

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