FCoE traffic disruption with changing QOS class weight

[dturnbu01]

Greetings, 

I know that as documented in CSCtq79496 when a QOS class disabled, enabled, or even has it's packet drop attribute changed that it will disrupt FCoE traffic. Will this also happen if I modify the weights?

Thanks!

[Windows Admins]

Hi,

in which FW version this BUG fixed.

Regards,

[Kirk J]

That was just filed as an 'info' type bug, to note that it is expected behavior to see a potential brief disruption when modifying QOS related settings.

This is likely due to reprogramming of ASICs that has to occur.

Thanks,

Kirk...

[Windows Admins]

Thanks Kirk,

I appreciate answering my below concerns

1- Enable or Disable QOS class should happen during maintenance windows even if it is not in use?.

2- Is this will lead for all FIC cluster to drop all fiber and Ethernet packets that does not use any of those QOS Class?

Thanks

Waseam

[dturnbu01]

In response to your questions:

1 - Yes. Always have a maintenance window for any QoS change, there will ALWAYS be a disruption.

2 - Yes. Whenever you make a change to QoS every port within the domain will recalculate it's port buffer allocation and that will cause you to drop some amount of FCoE and Ethernet traffic, even if the QoS class isn't in use.

It's best to try stay away from using QoS in UCS, if you absolutely have to because adding bandwidth isn't possible, you should aim to make the smallest change possible, and be sure to test that change in a lab environment first.

Hopefully this clears things up for you.