Fibre Channel (SAN)

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Contributor
Posts: 30
Registered: ‎08-15-2007

Using Fabric Watch fencing to prevent latency issues caused by a faulty connection

Hello,

We have had Fabric Watch for many years. I have been looking at the port fencing feature.  It looks like the solution to single connections causing SAN wide latency,  but have been scared by the possibility that under the wrong circumstances it could potentially disable both SAN A and SAN B connections to a single server, or potentially disable all ISLs to an edge switch.  Are there some safeguards for this?   Also does a fencing event trigger SNMP alerts - if it was to get fired off then I would want someone looking at it straight away.

Valued Contributor
Posts: 761
Registered: ‎06-11-2010

Re: Using Fabric Watch fencing to prevent latency issues caused by a faulty connection

hi,

 

i would not configure port fencing on a ISL port. On the other hand, yes, you can configure snmp traps/mails/events to be reported when a port is disabled by port fencing.

 

rgds,

Felipon

Frequent Contributor
Posts: 130
Registered: ‎02-05-2014

Re: Using Fabric Watch fencing to prevent latency issues caused by a faulty connection

I would use Fencing on E-ports but just resticted to errors of a physical nature. (Encoding/Decoding, CRC, LO-SYNC, LO-SIG etc.) These are the errors that the switch cannot correct and will cause havoc in the fabric.

I would not use fencing for latency or congestion since the causes are most often somewhere else.

 

Using fencing on F-ports for latency purposes is a good idea. If a port hit a threshold and is shutdown it immediatly relieves the remaining traffic of credit issues. Fencing a port for congestion is asking for more trouble since the MPIO layers on hosts will just redirect the same traffic onto another path resulting in the same problem. Congestion is a result of either bad planning or lack of operational management and monitoring.

 

Hope this helps.

Kind regards,
Erwin van Londen
Brocade Distinguished Architect
http://www.erwinvanlonden.net The Fibre Channel blog


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