Downgrading from a Higher Release
Use the install all command to reload the switch and handle configuration conversions. When downgrading any switch in the Cisco MDS 9000 Family, avoid using the reload command.
For example, to revert to Cisco MDS SAN-OS Release 1.3(4b) or 1.3(5) from Release 2.x, follow these steps:
Step 1 
Verify that the system image files for the downgrade are present on the active supervisor module bootflash:.
switch# dir bootflash: 12288 Jan 01 00:01:06 1980 lost+found/ 3821032 Apr 06 16:50:22 2006 m9000-ek9-ssi-mzg.2.1.1a.bin 14765056 Mar 21 15:35:06 2006 m9500-sf1ek9-kickstart-mz.1.3.4b.bin 15944704 Apr 06 16:46:04 2006 m9500-sf1ek9-kickstart-mz.2.1.1a.bin 48063243 Mar 21 15:34:46 2006 m9500-sf1ek9-mz.1.3.4b.bin 48036239 Apr 06 16:45:41 2006 m9500-sf1ek9-mz.2.1.1a.bin Usage for bootflash://sup-local 130642562 bytes used 53917054 bytes free 184559616 bytes total
Step 2 If the software image file is not present, download it from a FTP or TFTP server to the active supervisor module bootflash:. You can obtain the software image file from the Cisco.com software download center at the following URL:
http://www.cisco.com/public/sw-center/sw-stornet.shtml
Note 
If you need more space on the active supervisor module bootflash:, use the delete command to remove unnecessary files.
switch# copy ftp://ftpserver.cisco.com/MDS/m9500-sf1ek9-mz.1.3.4b.bin bootflash:m9500-sf1ek9-mz.2.1.2b.bin
Step 3 Issue the show incompatibility system image-filename command to determine if you need to disable any features not supported by the older release.
Switch# show incompatibility system bootflash:m9500-ek9-mz.1.3.4b.bin The following configurations on active are incompatible with the system image 1) Service :cfs , Capability :CAP_FEATURE_CFS_ENABLED_CALLHOME Description :CFS - Distribution is enabled for CALLHOME Capability requirement :STRICT 2) Service :cfs , Capability :CAP_FEATURE_CFS_ENABLED_PORT_SECURITY Description :CFS - Distribution is enabled for PORT-SECURITY Capability requirement :STRICT 3) Service :cfs , Capability :CAP_FEATURE_CFS_ENABLED_NTP Description :CFS - Distribution is enabled for NTP Capability requirement :STRICT 4) Service :cfs , Capability :CAP_FEATURE_CFS_ENABLED_TACACS Description :CFS - Distribution is enabled for TACACS Capability requirement :STRICT 5) Service :cfs , Capability :CAP_FEATURE_CFS_ENABLED_RADIUS Description :CFS - Distribution is enabled for RADIUS Capability requirement :STRICT
Step 4 Disable any features that are incompatible with the downgrade system image.
switch# config t switch(config)# no callhome distribute switch(config)# no port-security distribute switch(config)# no ntp distribute switch(config)# no tacacs+ distribute switch(config)# no radius distribute switch(config)# exit switch#
Step 5 Save the configuration using the copy running-config startup-config command.
Step 6 Issue the install all command to downgrade the software (see the “Upgrading SAN-OS Software on an Existing Cisco MDS Switch” section).
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