A Cisco MDS switch is shipped with the Cisco MDS NX-OS operating system for the Cisco MDS 9000 Series multilayer directors and fabric switches. The Cisco MDS NX-OS software consists of two images: the kickstart image and the system image.
The software image install procedure depends on the following factors:
Software images: The kickstart and system image files reside in directories or folders that can be accessed from the Cisco MDS 9000 Series multilayer switch prompt.
Image version: Each image file has a version.
Flash disks on the switch: The bootflash: resides on the supervisor module, and the CompactFlash disk is inserted into the slot0: device.
Supervisor modules: Either single or dual supervisor modules are present. To realize the benefits of a nondisruptive upgrade on the Cisco MDS 9700 Series multilayer directors, you should install dual supervisor modules per the Cisco recommendation.
To determine the version of the Cisco MDS NX-OS software that is currently running on a Cisco MDS 9000 switch using the CLI, log in to the switch and run the show version command in privileged EXEC mode.
Use the show incompatibility-all system bootflash: system image filename command to determine which features are incompatible with the destination upgrade release, as follows:
switch(config)# show incompatibility-all system
bootflash:m9700-sf4ek9-mz.8.4.1.bin
Checking incompatible configuration(s):
No incompatible configurations
Checking dynamic incompatibilities:
No incompatible configurations
No payload encryption (NPE) images are also available with the Cisco MDS NX-OS software. The NPE images are intended for countries that have import restrictions on products that encrypt payload data. To differentiate an NPE image from a standard software image, the letters NPE are included in the image. Nondisruptive software upgrades or downgrades between NPE images and non-NPE images are not supported.
You can upgrade any switch in the Cisco MDS 9000 Family using one of the following methods:
Automated, one-step upgrade using the install all command: This upgrade is nondisruptive. The install all command upgrades all modules in any Cisco MDS 9000 Family switch. Cisco recommends having dual supervisors installed on the MDS switch while performing a nondisruptive upgrade. Although a nondisruptive update doesn’t require a switch reload, it disrupts the control plane for about 80 seconds.
Quick, one-step upgrade using the reload command: This upgrade is disruptive and requires a switch reload. Before running the reload command, copy the correct kickstart and system images to the correct location in bootflash and change the boot commands in your configuration.
Note
An upgrade or downgrade of control plane software that results in the data plane going down for any period of time is called a disruptive (or hitful) upgrade or downgrade, respectively. This includes a stateless restart. An upgrade or downgrade of control plane software that does not take down the data plane for any period of time is called a nondisruptive (or hitless) upgrade or downgrade, respectively. This includes a stateful restart.
When the Cisco MDS Series switch is first switched on or during reboot, the switch follows the boot sequence shown in Figure 11-2.
Figure 11-2 Boot Sequence
The BIOS on the supervisor module first runs power-on self-test (POST) diagnostics and then runs the loader bootstrap function. The boot parameters are held in NVRAM and point to the location and name of both the kickstart and system images. The loader obtains the location of the kickstart file, usually on bootflash, and verifies the kickstart image before loading it.
The kickstart loads the Linux kernel and device drivers and then needs to load the system image. Again, the boot parameters in NVRAM should point to the location and name of the system image, usually on bootflash. The kickstart then verifies the system image and loads it.
Finally, the system image loads the Cisco NX-OS software, checks the file systems, and proceeds to load the startup configuration, containing the switch configuration, from NVRAM.
If the boot parameters are missing or have an incorrect name or location, the boot process fails at the last stage. If this happens, the administrator must recover from the error and reload the switch. The install all command is a script that greatly simplifies the boot procedure and checks for errors and the upgrade impact before proceeding.
We discuss the disruptive and nondisruptive upgrade and downgrade procedures in detail in the following sections.