Upgrading the NX-OS on a Cisco MDS 9148 Fabric Switch is a straight forward task. There are only three commands to upgrade the NX-OS, two copy commands and the install command which does all the work. First you need a TFTP server on the same network as the management interface to transfer the files over to the boot flash.

These are the only commands you need to upgrade the NX-OS:

copy tftp://192.168.1.2/m9100-s3ek9-kickstart-mz.5.2.1.bin bootflash:/
copy tftp://192.168.1.2/m9100-s3ek9-mz.5.2.1.bin bootflash:/
install all kickstart bootflash:/m9100-s3ek9-kickstart-mz.5.2.1.bin system bootflash:/m9100-s3ek9-mz.5.2.1.bin

This is the install process. After the process has verified the uploaded files press “Y” to continue the installation. Easy peasy.

mds9148# install all kickstart bootflash:/m9100-s3ek9-kickstart-mz.5.2.1.bin system bootflash:/m9100-s3ek9-mz.5.2.1.bin

Verifying image bootflash:/m9100-s3ek9-kickstart-mz.5.2.1.bin for boot variable "kickstart".
[####################] 100% -- SUCCESS

Verifying image bootflash:/m9100-s3ek9-mz.5.2.1.bin for boot variable "system".
[####################] 100% -- SUCCESS

Verifying image type.
[####################] 100% -- SUCCESS

Extracting "system" version from image bootflash:/m9100-s3ek9-mz.5.2.1.bin.
[####################] 100% -- SUCCESS

Extracting "kickstart" version from image bootflash:/m9100-s3ek9-kickstart-mz.5.2.1.bin.
[####################] 100% -- SUCCESS

Extracting "bios" version from image bootflash:/m9100-s3ek9-mz.5.2.1.bin.
[####################] 100% -- SUCCESS

Performing Compact Flash and TCAM sanity test.
[####################] 100% -- SUCCESS

Performing module support checks. 												   [####################] 100% -- SUCCESS

Notifying services about system upgrade. 										   [####################] 100% -- SUCCESS

Compatibility check is done:
Module  bootable          Impact  Install-type  Reason
------  --------  --------------  ------------  ------
     1       yes  non-disruptive         reset

Images will be upgraded according to following table:
Module       Image                  Running-Version(pri:alt)           New-Version  Upg-Required
------  ----------  ----------------------------------------  --------------------  ------------
     1      system                                   5.0(1a)                5.2(1)           yes
     1   kickstart                                   5.0(1a)                5.2(1)           yes
     1        bios     v1.0.18(01/07/10):  v1.0.18(01/07/10)     v1.0.19(02/01/10)           yes

Do you want to continue with the installation (y/n)?  [n]

Install is in progress, please wait.

Performing runtime checks.                                                         [####################] 100% -- SUCCESS

Notifying services about the upgrade.                                              [####################] 100% -- SUCCESS

Setting boot variables.
[####################] 100% -- SUCCESS

Performing configuration copy.
[####################] 100% -- SUCCESS

Module 1: Refreshing compact flash and upgrading bios/loader/bootrom.
Warning: please do not remove or power off the module at this time.
[####################] 100% -- SUCCESS

Upgrade can no longer be aborted, any failure will result in a disruptive upgrade.

Freeing memory in the file system.                                                 [####################] 100% -- SUCCESS

Loading images into memory.                                                        [####################] 100% -- SUCCESS

Saving linecard runtime state.                                                     [####################] 100% -- SUCCESS

Saving supervisor runtime state.                                                   [####################] 100% -- SUCCESS

Saving mts state.                                                                  [####################] 100% -- SUCCESS

Rebooting the switch to proceed with the upgrade.
All telnet and ssh connections will now be temporarily terminated.

After the installation has completed, it will drop your SSH session. Login and perform a “show version” to verify that the upgrade completed successfully.

mds9148# show version
Cisco Nexus Operating System (NX-OS) Software
TAC support: http://www.cisco.com/tac
Documents: http://www.cisco.com/en/US/products/ps9372/tsd_products_support_serie
s_home.html
Copyright (c) 2002-2011, Cisco Systems, Inc. All rights reserved.
The copyrights to certain works contained herein are owned by
other third parties and are used and distributed under license.
Some parts of this software are covered under the GNU Public
License. A copy of the license is available at
http://www.gnu.org/licenses/gpl.html.

Software
  BIOS:      version 1.0.19
  loader:    version N/A
  kickstart: version 5.2(1)
  system:    version 5.2(1)
  BIOS compile time:       02/01/10
  kickstart image file is: bootflash:///m9100-s3ek9-kickstart-mz.5.2.1.bin
  kickstart compile time:  12/25/2020 12:00:00 [07/16/2011 23:02:15]
  system image file is:    bootflash:///m9100-s3ek9-mz.5.2.1.bin
  system compile time:     6/7/2011 13:00:00 [07/17/2011 01:17:25]

Hardware
  cisco MDS 9148 FC (1 Slot) Chassis ("1/2/4/8 Gbps FC/Supervisor-3")
  Motorola, e500v2  with 1036300 kB of memory.
  Processor Board ID JAF1529CJAE

  Device name: mds9148
  bootflash:    1015056 kB
Kernel uptime is 0 day(s), 0 hour(s), 1 minute(s), 48 second(s)

Last reset at 73485 usecs after  Thu Mar  1 06:37:44 2012

  Reason: Reset due to upgrade
  System version: 5.0(1a)
  Service:

After this you can clean up the old versions of the NX-OS on the boot flash once you’ve tested there are no reasons to revert back to the original version.