This will be the first in a 3 part series of Citrix Cloud for Business Continuity and High Availability design articles
You may have noticed Citrix Cloud is at a 99.9% SLA. You may want the service to be guaranteed to be 99.999% available (or greater). In this article, I’ll explain why the service usability (as in, users can get their job done) can actually be even higher than that. All it takes is a few design decisions and configuration settings, and as long as your VDA’s are actively running and your users have Citrix Workspace App installed, Cloud outages and/or the unavailability of the internet from your WAN won’t prevent your users from launching their favorite virtual apps and desktops. Let’s get right into it.
Option 1: Roll with out of the box options and still get greater than 99.9%
As it “ships”, Citrix Cloud DaaS is made up of 3 primary solution components. From a user’s perspective, they login to the Gateway Service (a cloud.com (or custom) URL), they see icons presented from the Workspace Service, and they launch apps and desktops managed via Citrix DaaS. This combination has an SLA of 99.9%, which equates to roughly 8 hours of downtime over the span of a year. If we’re being honest, I’d bet you’d find that’s comparable to on-prem implementations, given downtime for late night patching, updates gone awry, and random LAN/WAN issues (because “it’s always the network” right?). But, if that 8 hours of Citrix DaaS downtime were to occur at the wrong time(s), you might be fielding questions of why a decision was made to offload this tier 0/1 service to the vendor hosted model.
However, with one flick of the click in Citrix Cloud, you likely can add at least another nine to that uptime guarantee. To do so, enable “Service Continuity”
With Service Continuity, the entire Citrix DaaS backplane can be down or inaccessible and your users can still launch apps and desktops.
And as long as a Gateway Service PoP (point of presence) can answer the requests from your remote users, those users should also be able to continue launching apps and desktops they’ve at least launched once before. As Gateway PoP’s are now near 50 spread between multiple public cloud locales, this should be the reality.
Sounds good, right? To enable the feature, go to Workspace Configuration, Service Continuity, and click Enable:
Once this is done, to enable both WAN and over internet operability in the event of outages, issue the following CMDLET from a machine running the Citrix Remote Powershell SDK:
Set-ConfigZone -InputObject (get-configzone -ExternalUid resourceLocation GUID ) -EnableHybridConnectivityForResourceLeases $true
Resource Location GUID’s are located under Home > Resource Locations in Citrix Cloud console. Find it by clicking ID:
Finally, verify the following:
VDA’s are version 7.15 LTSR or higher
Minimum Workspace App Versions:
- Citrix Workspace app 2106 for Windows
- Citrix Workspace app for Android 22.2.0
- Citrix Workspace app 2106 for Mac
- Citrix Workspace app for iOS 22.4.5
- Citrix Workspace app 2106 for Linux
Service Continuity is also available for users who launch apps and desktops via the Workspace web interface (a large percentage in my experience!). We will need a bit of prep work there as we need some browser plugins available for Chrome and Edge.
Also, Workspace App is required to be at the following versions or higher for browser based app launch during
- Citrix Workspace app 2109 for Windows at a minimum. Supported with Google Chrome and Microsoft Edge.
- Citrix Workspace app for Mac version 2112 at a minimum. Supported with Google Chrome.
- Citrix Workspace app for Mac version 2206 at a minimum for use with Safari browser.
And that’s pretty much it! Citrix has made the process extremely simple, allowing for continued operation even if a DaaS related service should become unavailable. Hopefully this alleviates any concern with Citrix Cloud hosting of the control plane and gateway; the service has been remarkably solid and improving since release.
In the next posting, we’ll go over Option 2: Use Citrix Cloud for management, keep more on-premises, and get 100% uptime by betting on yourself, your Netscalers, and your Storefront, using Local Host Cache.
In posting 3, we’ll cover high availability for VDA’s in multiple datacenters and clouds.
Hit me up in the meantime should you need any assistance or have any questions!
(c) 2022 Adam Paul Shattuck
