Cisco Cisco MDS 9000 NX-OS Software Release 5.0

Disable all features not supported by the downgrade release. Use the show incompatibility system 
downgrade-image command to determine what you need to disable. 

Use the show install all impact downgrade-image command to determine if your downgrade will 
be nondisruptive. 

Be aware that some features impact whether a downgrade is disruptive or nondisruptive:

Fibre Channel Ports: Fibre Channel ports can be nondisruptively downgraded without 
affecting traffic on the ports. See 

 for the nondisruptive downgrade path for all SAN-OS 

releases.

SSM: Intelligent services traffic on the SSM, such as SANTap, NASB, and FC write 
acceleration, is disrupted during a downgrade. SSM Fibre Channel traffic is not.

Gigabit Ethernet Ports: Traffic on Gigabit Ethernet ports is disrupted during a downgrade. 
This includes IPS modules and the Gigabit Ethernet ports on the MPS-14/2 module, the 
MSM-18/4 module, and the MDS 9222i switch. Those nodes that are members of VSANs 
traversing an FCIP ISL are impacted, and a fabric reconfiguration occurs. iSCSI initiators 
connected to the Gigabit Ethernet ports lose connectivity to iSCSI targets while the downgrade 
is in progress.

IVR: With IVR enabled, you must follow additional steps if you are downgrading from Cisco 
SAN-OS Release 2.1.(1a), 2.1(1b), or 2.1.(2a). See the 

 for these instructions.

FICON: If you have FICON enabled, the downgrade path is different. See the 

.

A downgrade from NX-OS Release 4.2(1b) to SAN-OS Release 3.3(1x) is not supported on MDS 
switches, when FC-Redirect based applications, such as Data Mobility Manager or Storage Media 
Encryption, are configured in the fabric if either of the following conditions are satisfied:

A target for which FC-Redirect is configured is connected locally and there are Generation 1 
modules with ISLs configured in the switch.

A host, for which FC-redirect is configured, is connected locally on a Generation 1 module.

If these conditions exist, remove the application configuration for these targets and hosts before 
proceeding with the downgrade.