Merge pull request #179302 from sefriend/autoscale-doc-updates

Autoscale documentation updates

Author: AnnaMHuff

articles/virtual-desktop/autoscale-faq.yml

@@ -17,10 +17,10 @@ sections:
   - name: Ignored
     questions:
       - question: |
-         How do I configure autoscale so I run zero session hosts after working hours?
+         How do I configure the autoscale feature so I run zero session hosts after working hours?
         answer: |
          Ramp-down mode always uses the lowest possible number of session hosts possible. However, if active sessions exist, the lowest number of usable session hosts won't be zero. Configure a time limit policy to sign out all disconnected users to avoid having usable session hosts after hours.
-          
+
       - question: |
          Does autoscale create or delete virtual machines (VMs) based on service load?
         answer: |
@@ -29,10 +29,44 @@ sections:
       - question: |
          Can I configure scaling for specific dates like holidays?
         answer: |
-         No. Autoscale doesn’t currently support ramping down on specific dates.
+         No. The autoscale feature  doesn’t currently support ramping down on specific dates.
 
       - question: |
          Will I be charged extra for using the autoscale feature?
         answer: |
          No. For more information on rates, see [our pricing page](https://azure.microsoft.com/pricing/details/virtual-desktop/).
-          
+      
+      - question: |
+         What happens if the host pool capacity is equal to the capacity threshold?
+        answer: |
+         Nothing. The autoscale feature only reacts when the host pool capacity is greater than or less than the capacity threshold. The feature won't do anything when the host pool capacity is the same as the capacity threshold.
+
+      - question: |
+         If I set drain mode on session hosts, will the autoscale feature change my configured setting?
+        answer: |
+         Yes, the autoscale feature will still turn VMs in drain mode on or off, no matter who put it in drain mode. The autoscale feature overrides drain mode on all VMs included in scaling, so if you want to exclude a VM from scaling actions, you must use exclusion tags.
+      
+      - question: |
+         How often does the autoscale feature monitor the session hosts and perform scaling evaluations?
+        answer: |
+         The autoscale feature monitors for when users sign in or out of their session hosts and categorizes this activity as session change events. Session change events trigger a scaling evaluation that creates logs. If there aren't any session change events or the event service has an outage, the autoscale feature then checks to see if it missed any events. When several session change events happen within a short time period, hen the feature will batch the scaling evaluations. This batching allows the autoscale feature to process large numbers of events quickly without overloading the system.
+
+      - question: |
+         Can force sign-out happen in any phase of the day?
+        answer: |
+         No. If you've enabled the autoscale feature, you can only force users to sign out during the ramp-down phase. This means that if, during ramp-down, a session host is put in drain mode in preparation for it to be shut down but not all users get signed out before the phase changes to off-peak, the remaining user sessions will not be forced to sign out from their session. This is because during off-peak hours, users aren't forced to sign out of their sessions. Instead, the autoscale feature will wait until all users have signed out before deallocating the VM. For example, if the ramp-down phase is 15 minutes long, and the wait time before signing out users and shutting down VMs is 20 minutes long, the schedule will shift to the off-peak phase and the user sessions will not be forced to sign out.
+      
+      - question: |
+         If I configure the autoscale feature to force users to sign out during ramp-down, will it also sign out users with active sessions?
+        answer: |
+         Yes. Idle, disconnected, and active sessions will be forced to sign out if the users don't sign out during the ramp-down phase wait time.
+
+      - question: |
+         If an active session is forced to sign out, but the user tries to reconnect, is there a way to prevent them from starting a new session on a session host that the autoscale feature is about to turn off?
+        answer: |
+         After the autoscale feature selects a session host to be shut down, it puts the session host in drain mode. Once all the user sessions have been signed out, the autoscale feature deallocates the VM. After deallocating the VM, the autoscale feature sets the AllowNewSessions setting to true, which turns off drain mode. Because sessions hosts that are about to be shut down are put in drain mode, a user who is forced to sign out of their session won't connect to a session host that is about to be shut down if they try to reconnect.
+
+      - question: |
+         Can the autoscale feature turn off all the VMs in a host pool, or does it need to keep at least a few VMs on to work properly?
+        answer: |
+         The autoscale feature can turn off all the VMs in a host pool if the minimum percentage of hosts is set to **0%** and there are no user sessions on the session host.

articles/virtual-desktop/autoscale-scaling-plan.md

@@ -206,13 +206,13 @@ To create or change a schedule:
         >[!NOTE]
         >The load balancing preference you select here will override the one you selected for your original host pool settings.
 
-    - For **Minimum percentage of session host VMs**, enter the amount of session host resources you want to use during ramp-up and peak hours. For example, if you choose **10%** and your host pool has 10 session hosts, autoscale will keep one session host available for user connections at all times during ramp-up and peak hours.
+    - For **Minimum percentage of hosts**, enter the percentage of session hosts you want to always remain on in this phase. If the percentage you enter isn't a whole number, it's rounded up to the nearest whole number. For example, in a host pool of 7 session hosts, if the minimum percentage of hosts is **10%** for the ramp-up hours, one VM will always stay on during ramp-up hours and the autoscale feature won't turn off this VM. 
     
-    - For **Capacity threshold**, enter the percentage of host pool usage that will trigger the start of the ramp-up and peak phases. For example, if you choose **60%** for a host pool that can handle 100 sessions, autoscale will only turn on additional hosts once the host pool goes over 60 sessions.
+    - For **Capacity threshold**, enter the percentage of available host pool capacity that will trigger a scaling action to take place. For example, if 2 session hosts in the host pool with a max session limit of 20 are turned on, the available host pool capacity is 40. If you set the capacity threshold to **75%** and the session hosts have more than 30 user sessions, the autoscale feature will turn on a third session host. This will then change the available host pool capacity from 40 to 60.
 
 5. In the **Peak hours** tab, fill out the following fields:
 
-    - For **Start time**, enter a start time for when your usage rate is highest during the day. Make sure the time is in the same time zone you specified for your scaling plan. This time is also the end time for your ramp-up phase.
+    - For **Start time**, enter a start time for when your usage rate is highest during the day. Make sure the time is in the same time zone you specified for your scaling plan. This time is also the end time for the ramp-up phase.
 
     - For **Load balancing**, you can select either breadth-first or depth-first load balancing. Breadth-first load balancing distributes new user sessions across all available sessions in the host pool. Depth-first load balancing distributes new sessions to any available session host with the highest number of connections that hasn't reached its session limit yet. For more information about load-balancing types, see [Configure the Azure Virtual Desktop load-balancing method](configure-host-pool-load-balancing.md).
 
@@ -227,6 +227,9 @@ To create or change a schedule:
       - Capacity threshold (%)
       - Force logoff users
 
+    >[!IMPORTANT]
+    >If you've enabled the autoscale feature to force users to sign out during ramp-down, the feature will choose the session host with the lowest number of user sessions to shut down. The autoscale feature will put the session host in drain mode, send all active user sessions a notification telling them they'll be signed out, and then sign out all users after the specified wait time is over. After the autoscale feature signs out all user sessions, it then deallocates the VM. If you haven't enabled forced sign out during ramp-down, session hosts with no active or disconnected sessions will be deallocated.
+
     - Likewise, **Off-peak hours** works the same way as **Peak hours**:
 
       - Start time, which is also the end of the ramp-down period.