Many organizations might have plan to upgrade their existing Lync infrastructure and waiting for Skype for Business general availability. Skype for Business green field deployment is almost same as it was in Lync Server 2013. If you are planning for in-place upgrade of Lync Server 2013 infrastructure, you will have to consider many best practices. There are a few key recommendations which you should consider while planning for In-Place upgrade.

Before going to talk about the recommendation for in-place upgrade, would like to clear “Skype for Business In-place upgrade only supports vanilla Lync Server 2013 infrastructure”. For more details and options please go through my preceding blog post Skype for Business: In-Place Upgrade and Migration Path.

There are two options for In-Place upgrade:

1. Migrate-users mode (No user downtime): Basically, this option is only available if organization has more than one Lync Server 2013 pool (Don’t consider paired/secondary/backup pool). With this option administrator has to move all the users from the primary registrar pool to any other Lync Server 2013 pool and upgrade the primary pool. Once FE pool and associated server roles have been upgraded then move the users back to the primary pool. Follow the same process for multiple pools.
   

2. Offline mode (Downtime require): You can consider this option if the organization has only single pool or two pools in backup/paired pool configuration. This method requires downtime or you can upgrade Lync Server 2013 infrastructure in non-business hours or weekends. Please make sure entire upgrade process should be occur in one shot and till that time Lync Services will not be available to end users.
   

For both the options Lync Server 2013 infrastructure should be updated with Lync Server 2013 CU5 before starting the in-place upgrade process.

Below are the key recommendation while planning for in-place upgrade.

• No in-place upgrade with pool failover option

  Don’t use failover cmdlet to failover the primary pool to backup pool and start in-place upgrade in primary pool. This method is not supported.

• Don’t start services in mixed mode while upgrading.
• Don’t unpair the pools before completing upgrade process in paired pool environment.
• Ensure minimal downtime when the pools are paired with different versions.

Upgrade Order: Inside – Outside

1. Users pools first
2. Shared components like Mediation Server, Director etc.
3. Edge
4. CMS pool