Azure cloud service - update domain

in flag

Related - but not the same: Azure Cloud Service Upgrade Domain server restart interval

I have a cloud service (extended support) in Azure with two instances of a role, in an availability set, with different value for Update Domain - 0 and 1 - as can be seen in this screenshot.

enter image description here

When a deployment runs, or VMs are being updated by Azure (e.g. windows updates, etc.), I expect that the VM in Update Domain 0 would be completed and back up to "Started" state before the VM in Update Domain 1 would start the update. Unfortunately this is not the case.

Each VM startup takes a significant amount of time (around an hour) due to having to install custom software, copy data, start relevant services, etc. What I'm seeing is that instance in Update Domain 0 is being updated first, it's in status "Starting" while the other instance is in status "Started". Then after about 30-40 minutes, while the instance in Update Domain 0 is still in "Starting" state, the second instance starts its update process - resulting in both VMs being in "Starting" state - and as a result, the service is down for up to 20 minutes or so until the first instance completes the update.

I have another similar cloud service with 3 instances - I'm seeing exact same behaviour there. There's a period of about 5 minutes when all 3 instances are in status "Starting", even though they are in 3 different Update Domains.

Am I missing something or is this a bug of some sort in Azure Fabric? Maybe there's a hard limit on how long the fabric will wait before proceeding with the next instance?

EDIT: Here's a screenshot of both instances being updated at the same time, even though they are in different Update Domains:

enter image description here

I sit in a Tesla and translated this thread with Ai:


Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.