The default FLOGI quiesce timeout was set to 2000ms as default in CISCO MDS NX-OS 8.1 and 8.2.
The default for 8.3(1) (possibly 8.3) is 0, which disables the feature.
However the Upgrade/Downgrade process follows the logic of, once a value is set, it will not be changed.
Hence, if the MDS had 8.1 or 8.2 installed, it will keep the 2000ms value.
In the MDS guide under Managing FLOGI it is noted:
"This feature must be disabled by setting the timeout value to zero when there are devices in the fabric that can share a pWWN at different times by logging into different switches within the fabric during failover situations."
To summarize why this value caused issues:
- We preserve the path to the LIFs during switchover / switchback, hence we use pWWWN sharing
- "The FLOGI Quiesce Timeout feature causes the FLOGI process to delay notifications to the other Fibre Channel services such as Routing Information and Fibre Channel Name Server when a device logs out from a fabric or when an interface goes down."