A thousand sessions can look healthy on a protocol dashboard and still fail the morning. Connected is not ready. ICA RTT green is not a published app painted. An HTTP soak of Workspace or the RD Web portal times the front door, not the farm. For Citrix, Microsoft RDS / RemoteApp, and cloud VDI, load that matters is load that waits for pixels.
Direct answer: CitraTest VU is Tevron’s on-the-glass load testing product. Virtual users connect like real clients. Image recognition waits for what appears on screen (WaitForImage). There are no agents on production session hosts. Concurrency and ramp measure readiness from the glass – not HTTP-only or ICA/RDP-only counters.
This post is the product and method piece: why VU load testing that waits for pixels beats protocol-only load tools for EUC. Sister how-tos cover the walk-throughs – how to load test Citrix, Microsoft RDS, cloud VDI – and the response-time series times one session on the glass. Entity page: what is CitraTest VU. Blog home: Tevron Blog.
Why a thousand green sessions can still miss the morning
EUC remotes desktops and published apps as bitmaps. Users wait for a shell, a published-app first paint, and an in-session ready state. Protocol tools are good at answering “did the channel stay up?” They are weak at answering “did the UI become usable at concurrency N?”
An HTTP generator that hammers StoreFront, Gateway, or RD Web can finish green while HDX or RDP never paints a usable desktop. A session-count or ICA/RDP counter can stay green while the published app spins. Host CPU at 40 percent does not close the ticket when click-to-ready stretches under ramp. That is the gap CitraTest VU is built for.
A thousand sessions. One pixel clock. Capacity you can defend is concurrency that paints ready – not concurrency that only connects.
Left column is what protocol and portal soaks see. Right column is what CitraTest VU times under concurrency. Only the glass column is EUC readiness as people experience the farm.
What CitraTest VU actually does
CitraTest VU drives real client paths – Citrix Workspace / HDX, Microsoft RDS / RemoteApp, and cloud VDI sessions – with virtual users that behave like people at the glass. Each VU:
- Connects like a real client – not a synthetic HTTP hit against the store URL alone.
- Waits for pixels – WaitForImage (and OCR when the ready state is text) until shell, published app, or in-session chrome matches a baseline.
- Records the interval – StartTimer at the user action, StopTimer when the ready image matches.
- Needs no agent on production hosts – measurement stays on the glass side of the remoting path.
That is load testing for EUC as EUC behaves. Product overview: CitraTest VU load testing. Checklist-style Citrix walk: how to load test Citrix.
Ramp, concurrency, and the pixel clock
Write the load shape before you pick a pass/fail. Two shapes stay separate:
- Logon storm – many users arriving together. Stresses login-to-shell and the front-door launch path.
- Density / sustain – many users already in session doing work. Stresses published-app and in-session click-to-ready on hosts that already have load.
Blending them hides which interval broke. Run them as separate tests. Under either shape, the acceptance line is glass time at a written percentile – not “sessions connected” or “ICA RTT stayed green.” See also logon storm vs density.
The pipeline is the same idea across platforms. Change the client path and the ready image. Keep the timer. That is how one product covers Citrix Virtual Apps and Desktops / DaaS, Microsoft RDS / RemoteApp, and cloud VDI without rewriting the meaning of “ready.”
Where protocol-only tools stop short
- They can pass an HTTP soak while HDX or RDP never paints a usable shell.
- They can report session-up while the published app is still spinning.
- They can show healthy RTT while in-session click-to-ready fails at density.
- They cannot attach a screenshot of the failed ready state the way a glass timer can.
Keep protocol tools for the remoting path. Keep portal HTTP checks for the front door. Put capacity decisions on glass time under ramp. That split is the same product language as Citrix HDX vs real user experience and Tevron vs common load testing tools.
Load test versus continuous watch
On-the-glass is a method. Two jobs share the path:
- CitraTest VU – load and change validation. Freeze the image, walk the client path, ramp concurrency, stop at the written glass budget. Product: CitraTest VU.
- CitraTest APM – continuous synthetic watch in production. Same glass steps on a schedule, with alerts when click-to-ready slips. Product: CitraTest APM.
Do not use a load-test generator as your only production monitor. The lab answers how many good concurrent workflows fit. The watch answers whether today’s path is still inside the line. Stack timing sister post: First Useful Pixel: Timing the Citrix Stack.
What this is not
- It is not an HTTP soak of Workspace, StoreFront, Gateway, or RD Web alone.
- It is not “sessions connected, so capacity is proven.”
- It is not a replacement for Director, Monitor, or RD session host counters – keep those for the remoting path.
- It is not the Citrix / RDS / cloud how-to walk-through (see the sister load-test guides).
- It is not a response-time article for one ERP or EHR GUI – those live in the measure series.
- It is not a claim about proprietary broker internals – only delivered UI readiness under concurrency.
Defend the number the morning can survive
CitraTest VU load testing measures EUC capacity from the glass: real client sessions, WaitForImage readiness, ramp and concurrency without agents on production hosts. A thousand sessions only count when the pixel clock says ready. Protocol green is useful. It is not the CAB number.
When you need that path for Citrix, RDS, or cloud VDI – schedule a demo. Start here: CitraTest VU, what is CitraTest VU, and the Tevron blog.
Citrix, HDX, ICA, StoreFront, Workspace, Microsoft, Remote Desktop Services, RemoteApp, and related marks are trademarks of their respective owners. Tevron is not affiliated with Citrix or Microsoft. Names are used for identification only.