Fibre Channel (SAN)

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Occasional Contributor
Posts: 17
Registered: ‎10-09-2014

Viewing virtual channel throughput

Does anyone know a way of viewing throughput per virtual channel?  We're trying to test SAN QOS, and it'd be nice to be able to see a rough view at least that it's doing what we expect.  Thanks.

External Moderator
Posts: 4,787
Registered: ‎02-23-2004

Re: Viewing virtual channel throughput

i.e. "portperfshow"

TechHelp24
Occasional Contributor
Posts: 17
Registered: ‎10-09-2014

Re: Viewing virtual channel throughput

I've never known portperfshow to show anything more than the throughput for a port.  What we're looking for is the throughput for each virtual channel.  Something like the zero credit counter in a portstatsshow.

External Moderator
Posts: 4,787
Registered: ‎02-23-2004

Re: Viewing virtual channel throughput

-->>Something like the zero credit counter in a portstatsshow.

 

what are the value of "portcfgeportcredit --show"

 

 

 

TechHelp24
Occasional Contributor
Posts: 17
Registered: ‎10-09-2014

Re: Viewing virtual channel throughput

"E-Port Credit Configuration is not Enabled"

External Moderator
Posts: 4,787
Registered: ‎02-23-2004

Re: Viewing virtual channel throughput

If the problem is caused due a bottleneck, I would suggest to enable and set the buffer credit value.

 

 

TechHelp24
Occasional Contributor
Posts: 17
Registered: ‎10-09-2014

Re: Viewing virtual channel throughput

There is no problem.  I'm wondering if anyone knows how to view the throughput/traffic down a virtual channel or down a particular QOS group.

 

It might be that I'm missing the point.  My understanding is that when you use QOS, if a port becomes congested, the high priority traffic will get to go first.  Or is it purely a buffer thing, allocating more buffers to high priority traffic, but then if a port is at 99% utilisation, traffic in any VC will get through?

External Moderator
Posts: 4,787
Registered: ‎02-23-2004

Re: Viewing virtual channel throughput

->I'm wondering if anyone knows how to view the throughput/traffic down a virtual channel or down a particular QOS group.

 

I don't know how you can view such a traffic, i was the opinio portperfshow should work.

 

->There is no problem. 

 

Is problable that this is not a problem, now I'm not sure if you are looking for a solution or just how to view the traffic.

 

->Or is it purely a buffer thing, allocating more buffers to high priority traffic, but then if a port is at 99% utilisation, traffic in any VC will get through?

 

if the port in question congest, ( in example if the port is set as LE, the port in question should become more Buffer allocated, but due the aoutomatic allocated buffer this will be distributed across the port's )

 

->My understanding is that when you use QOS, if a port becomes congested, the high priority traffic will get to go first. 

 

the goal from portcfgeportcredit is, to assign to a affected port a required buffer.

TechHelp24
Valued Contributor
Posts: 524
Registered: ‎03-20-2011

Re: Viewing virtual channel throughput

Sorry, there's no command to see the traffic per VC. In a way, you can have a look at the tim_txcrd_z counters on the port, they have a breakdown per VC. So you might see if some of the VCs are highly utilized. Note that incoming and outgoing traffic might use different VCs. Maybe the Flow part of the MAPS can give some more insight, but I didn't use it yet so I can't tell for sure.
Occasional Contributor
Posts: 19
Registered: ‎09-23-2011

Re: Viewing virtual channel throughput

[ Edited ]

What do you mean by talking about VC throughput. It's not quite clear what do you want to measure. Physicaly you have the link and VCs are just something like queues. QOS will work only when ISL congestion occurs. Thus you will have 100% link utilization and some VCs will get more or less priority.

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