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Monday, September 20, 2010

Question on upgrading CUCM 4.2 to CUCM 7.1

We are looking for an upgrade strategy or ideas (cucm 4.2 to cucm 7.1). There are (2) clusters with 15K phones per cluster. These phones are spread out over 200 sites, some large ( more than 2000 phones) and some small (less than 20 phones). We have a couple of questions -

* When upgrading a CUCM server from a Windows based to a Linux based version it's better if you have new hardware and build parallel servers.This will give you a minimal impact, besides, probably the servers you currently have are not supported in later CUCM versions or are quite old. First of all, you need to check the correct upgrade path and if the servers you have are supported on the new CUCM version.You can click here for the documents. Also please click here for *** Supported Cisco Unified Communications Manager Releases by Server ***documents here.

* For a minimal upgrade downtime, you can take a BARS backup from the 4.X version and install it on a new server so you can recreate the production system. Then run the DMA process (multiple times if necessary to get a clean output) and install 7.1.X (or later) on this server. Afterwards you need to run extensive tests in the lab to verify all features and functionality work as desired. You can also test customized applications along with all the Cisco applications that would touch this cluster. Once everything looks good, you can take the new 7.1 server and place it in the data centers, connect it to the network with the switch port shut down. The night of the cut over just disable the switch ports for the production 4.X server, enable the switch ports for the 7.1 server, reboot the cluster and start your test plan.Then validate replication, enabled NTP, and DNS if used and that's it! This process is usually used for big clusters with a large number of users. Sometimes having the luxury of building out and testing in the Lab outweighs the cost of the new servers. And with this, you will also have an instant roll back option if you run into any issue and you reduce business impact. Usually when talking about large clusters, engineers spend months aggressively testing 7.1 in a Lab as well as a small user acceptance cluster. This testing helps ensure the migration is successful.

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