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We have recently added AAG to our production servers, for DR purposes. We have approximately 60 FCI clustered instances (SQL 2017) hosting ~5000 client databases. This is all hosted in our own datacenter. The FCI's are pairs with an on-duty and off-duty node, failing over at the beginning of and mid-month. These are the primaries in the AGs. The newly added secondaries are single server Iaas VMs hosted in Azure, 1 per FCI. The AGs are set to manual failover, asynchronous commit, and will never be failed over to except in a disaster recovery scenario. The question is, how do we apply SQL updates in this scenario? I believe the steps should be:

  • Suspend data movement for all DBs in the AG
  • Apply update to the AG secondary and restart
  • Resume data movement
  • Apply update to the off duty FCI node of the Primary and restart
  • After the next scheduled failover of the FCI, apply update to the now off-duty FCI node and restart

Hopefully my question is clear. I look forward to hearing from whomever has some input.

Thanks!

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The official documentation is located here, and your steps are correct except for the first, suspending data movement which isn't needed.

One item to be aware about is that the database won't have an upgrade done to it (whether CU, or major version) until it fails over (either FCI or AG) and a patched/upgraded node becomes primary. This can cause longer failover times for the first failover after patching or upgrading.

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  • Interesting. Non-clustered secondaries can be a bit testy so when I read one article recommending suspending data movement it felt right. Good to know it's not necessary. I had a look at the official documentation before posting and it didn't exactly cover our scenario so thought I'd best dot my t's before pulling the trigger. It's understood that the dbs won't be updated until an updated node becomes active. I certainly appreciate you taking the time to respond and share your insight Sean. Cheers Commented Jan 13 at 21:39

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