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CUCM Version 9.X Firmware Upgrade

Ng Tian Sheng

Hi All,


My customer's current CUCM version is, and they found out this version has OpenSSH LoginGraceTime Denial of Service vulnerability, so I decided to upgrade their current CUCM version to 


There are 1 CUCM Publisher and 3 Subscriber in their environment. My question will be if I perform the above upgrade, will the existing configuration lost after the upgrade? If I perform the backup at DRS, I also cannot restore the configuration after CUCM upgrade right? 


Because the customer's CUCM configuration is complicated and quite a lot, so I just worry after upgrading to version and the configuration is gone, I will have to reconfigure everything and since DRS restore can only performed on the same CUCM version.


Can someone please advise me?



5 Replies 5

Rising star
Rising star


CUCM will not blow away its configuration after the upgrade. Also the upgrade installs on the inactive partition and once installed it switches versions and the active partition (9.1.2-10000-28) becomes inactive and inactive partition ( becomes the active partition. If for any reasons you have issues, you can simply swap the active and inactive partition.



HTH Regards, Yosh

Hi Yosh,


Thanks for your quick response, what about if I upgrade CUCM version 9.X to 10.X? Will the configuration lost after upgrade?



Hi Ng Tian Sheng,


Just a rule of thumb about Cisco CCM Upgrades:


1. No, you almost NEVER lose any configuration on the Cisco Callmanager (aka Communications Manager) if you upgrade them, all the older configs are carried forward

2. To make sure you are covered just in case of any unplanned situation (i.e. HDD failure or power failure and corruption of the data)  ALWAYS make sure you have a latest copy of the verified DRS backup data available, it will be much easier to go back in case if you wanted to

3. Although not TAC recommended/supported, you could take Snapshot of the existing Servers in the VMWare and keep it as "one click fall back mechanism" to revert back quickly (however please keep in mind it is NOT to replace the DRS nor should be used in place of backup, but just in case scenarios)


More over, before you upgrade, check the compatibility matrix and make sure your current version (the complete version name) is included in the Direct Upgrade path to the version you want to upgrade to

Finally, make sure that you meet all the OVA requirements BEFORE you attempt the upgrade.


Please rate all helpful posts

+5 Wilson that's very helpful information

HTH Regards, Yosh

Thanks Wilson for the reply

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