Measuring the Impact of Folder Redirection – User Logon

This is the forth in a series of articles on folder redirection by Aaron Parker, Helge Klein and Shawn Bass.

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Previously in this Series

So far in this series on folder redirection, we’ve covered the basics of how folder redirection works, what the impact of folder redirection is on logon and application launch and in the previous article, Helge covered the impact on search in the Start menu. In this article, we’ll focus on actual measurements of that impact.

Measuring the Impact on Logon Performance

To measure the impact on performance of different configurations, including different profile sizes, folder redirection enabled or disabled and the file server under different stress conditions, we’ve used Helge’s own uberAgent in each of our environments. So while each environment was different, we’ve used the same methodology to measure the impact.

When we discuss profile sizes we referring to both the total size of the profile as well as the number of files in the profile. For these tests, we have 3 profile sizes:

  • Small: 114 files, 4.69 MB
  • Medium: 1,461 files, 19.9 MB
  • Large: 2,334 files, 33.7 MB

Before capturing metrics, each user account/profile has completed the first logon. The environment used consisted of Citrix XenApp 6.5 (Windows Server 2008 R2) with locally cached profiles deleted at logoff. The file server was running Windows Server 2008 R2.

Logon Times of Different Profile Sizes and No Folder Redirection

The following graph shows the logon time of user account configured for a roaming profile and with no folder redirection configured. We’ve averaged the logon times over a number of tests for small, medium and large roaming user profiles.

Logon impact of profile sizes with no folder redirection

This shows a predictable increase in logon time as the profile grows – the larger the profile, the longer the logon time takes. In this case, because we’re using roaming profiles with no folder redirection, the entire profile is copied locally at user logon.

Logon Times of Different Profile Sizes with Folder Redirection Enabled

Let’s use the same tests (same user account with the same small, medium and large profiles) and enable folder redirection for each of the user profile folders.

Logon impact of profile sizes with folder redirection

In this test, there is no statistically significant difference between logon times. The reason for a more consistent logon time is that with folder redirection, we aren’t copying data locally at logon, other than the user’s registry (NTUSER.DAT). In these tests, there won’t be much difference in the size of the registry, therefore the logon times are similar.

Logon Times of Different Profile Sizes with Citrix Profile Management

If we again use the same user profiles, but instead of folder redirection, we utilise Citrix Profile Management (CPM), then the results of the logon tests look like this:

Logon impact of profile sizes with Citrix Profile Management

The logon times are much better than roaming profiles and more consistent like with folder redirection enabled, but the differences in variation are a little more expressed.

The improvement in logon times over roaming profiles are significant for the medium and large profiles with the similarity in logon times across all three profiles types being down to the similar amount of data required to get the profile down and the desktop loaded (user registry and files immediately accessed). CPM will continue to stream the remainder of the profile down in the background, so perhaps initial application launch may be affected.

Measuring the Impact on File Server Load on Logon Performance

We’ve looked at different types of profile and folder redirection configurations which have produced reasonable results for logon performance, but each test was done with the file server hosting the user profile or the redirected folders in an idle state.

Let’s look at what happens if the file server is under 0% (idle), 80% and 99% CPU load. I’ve covered some common reasons for file server CPU load in my previous article, but as a refresher these could include AV scans, run away processes, servicing a large number of SMB requests, or CPU resource contention.

Logon Times of Different Profile Sizes and No Folder Redirection

With the first test, we’ll again use standard roaming user profiles and no folder redirection configured, so the entire profile is copied to the Windows desktop at logon.

Logon impact of profile sizes with roaming profiles and file server under load

This produces some interesting results – with a small roaming profile, there’s little impact on logon times when the file server CPU is at 80%, but for each of the remaining tests, we can see that file server CPU load, even at 80%, more than doubles the logon time.

When the file server effectively runs out of CPU resources (at 99%) the direct effect on the user experience is clearly visible. For the medium profile, there’s a 1200% increase in logon time and for the large profile, a 2071% increase! Don’t let your file server/s run out of CPU resources.

Logon Times of Different Profile Sizes with Folder Redirection Enabled

The same CPU load tests run again with folder redirection now enabled on the same user profiles. Folder redirection helps to even out the results when compared to the previous test.

Logon impact of profile sizes with folder redirection enabled and file server under load

Logon impact of profile sizes with folder redirection enabled and file server under load

At 80% load on the file server, there’s an impact on the logon. Users sensitive to changes in logon times will probably notice, but I suspect that the majority of users would not be affected.

However, looking at scenarios when the file server runs out of CPU resources (around 99%), it is just unable to service SMB requests in a reasonable time and the user logon times more than triple or quadruple.

Even though we’ve implemented folder redirection, by itself it’s not a silver bullet. It helps considerably for large profiles, but once the file serve is busy, users will see the impact on performance.

Logon Times of Different Profile Sizes with Citrix Profile Management

Let’s look again at the effectiveness of a streaming approach to profile and data access instead of folder redirection, while the file server is under load.

Logon impact of profile sizes with Citrix Profile Management and file server under load

Logon impact of profile sizes with Citrix Profile Management and file server under load

What’s interesting here, is that where folder redirection reduced the differences between the logon times of the different profiles sizes, Citrix Profile Management does not. This can be explained by the need to transfer additional file data locally. Files are streamed to the client as they are accessed, so it’s likely that more data is transferred than when using folder redirection.

This approach is still a significant improvement over roaming user profiles. So, if you combine folder redirection and profile management, you should get the best of both worlds to improve the logon experience.

But… don’t let your file server run out of CPU resources.

Conclusion

Based on these results, we can see the benefits of enabling folder redirection, especially if you’re using roaming user profiles. Combining folder redirection with 3rd party profile management solutions should further improve the logon experience.

For hosted desktop customers (Citrix XenApp, XenDesktop, VMware Horizon etc.) there are usually inbox solutions to profile management; however for physical desktops 3rd party licensing is often required (or UE-V is available as a part of MDOP).

Whatever the approach, these are only parts of the equation, as we’ve seen, file server performance is crucial to providing good user experience. More importantly, consistent file server performance is important.

Logon storms, transient environment issues and undersized file servers can have a direct impact on logon times.

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Long logon times makes users unhappy…

Visualizing the Impact of Folder Redirection – Logon and Application Launch

This is the second in a series of articles on folder redirection by Aaron Parker, Helge Klein and Shawn Bass.

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Vizualizing Impact on User Experience

In the previous article, Helge covered the under the hood details of folder redirection. Now let’s look at some possible scenarios that show the impact on the user experience with folder redirection enabled. In this article we’ll focus on the initial logon and application launch.

Test Environments

We performed several tests across three different environments on three continents. Nothing if not diverse. While we don’t have enterprise level hardware to test on in our own labs (well, maybe Shawn does), this has enabled us to ensure that we can replicate the results in different environments.

For the purposes of this initial round of tests, we’ve stuck with Windows 7 and Windows Server 2008 R2, which at the time of writing, are the most common versions of Windows in enterprise environments. This means that all testing was completed with SMB 2.1.

What we’ve attempted to show is the impact on user experience when based on common user profile sizes, profile configuration options (e.g. roaming profiles and 3rd party solutions) and redirecting different sets of folders.

Each test environment is simulating or utilising RDS or VDI solutions to demonstrate the scenarios. This means that the desktop is close to the file server that is hosting the user’s profile, home drive or locations for folder redirection. In this initial round of testing, we haven’t focussed on physical desktops or desktop separated from file servers by a WAN connection.

Demos

I’ve embedded a number of videos below that demonstrate the user experience for logon an application launch under different profile and folder redirection configurations and transient conditions.

Baseline

To demonstrate a baseline, this first video shows what a normal logon looks like. In this specific video, the user account is configured with a roaming profile (2,334 files, 33.7 MB total in size) but no folder redirection. Additionally the file server (hosting the user profile) is idle.

As you can see, logon is quick and once logon is complete the system is quite responsive. The general user experience is exactly what a user would expect from a well performing system.

File Server Under 99% Load

Now, let’s make no changes to the user account configuration (using the same profile), but put the file server under load by stressing the CPU. CPU load on the file server can be a common occurrence for various reasons – AV scans, run away processes, servicing a large number of SMB requests, or perhaps even CPU resources are limited due to contention on shared platforms (i.e. a hypervisor).

As you can see in the video above, the logon process is extended from seconds to over 3 minutes! With the file server under CPU load, it doesn’t have the capacity to service requests to transfer the profile down to the client in a timely manner.

With a profile that has thousands of files in it, each file transfer requires an open file/transfer data/close file sequence, so a lot of file requests can take a long time to service. Imagine the knock on effects of a file server under load with multiple concurrent logons.

Folder Redirection Enabled with File Server Under 99% Load

In the next test, we still have a roaming profile; however now we’ve enabled folder redirection for all of the most common folders, including AppData, Desktop, Favourites and Documents etc. This reduces the data that needs to be copied in at logon, so we should expect logon to be quick, but what happens after logon?

Even with the file server under load, the logon is fast as we aren’t dragging data across the network; however you’ll notice a few things post-logon:

  • It takes time for the shortcuts on the desktop to display the icon associated with the shortcut (even though each shortcut is to the same application).
  • The Libraries in Explorer take a long time to show child folders.
  • Launching Adobe Reader takes an long time as the application requests files from AppData which is now on a network location.
  • Internet Explorer 11 launch is reasonable, but longer than with previous tests.
  • Microsoft Word takes a long tome to launch as it too is requesting files from AppData as we can see from the splash screen.

In this scenario, we’ve traded slower performance over the session for improved logon speed. Where as logon is (usually) a one time action, application launch and operation delays will have a cumulative effect over the working session. Depending on the user’s activity, this could add up to more time than was saved during logon.

Citrix Profile Management with Folder Redirection Not Enabled

The next test actually reverses the scenario bit – we again have no folder redirection, but have augmented or replaced the roaming profile with a profile managed by Citrix Profile Management.

This approach uses streaming to bring the profile down to the desktop as data is requested. Data transfer is extended over the length of the session, rather than copied down before the logon process is complete.

This test demonstrates the streaming approach to profiles that Citrix Profile Management uses – files are copied down in the background as they are requested. The effect is that some actions are slower, so logon is slower than with folder redirection, but as the profile is fleshed out locally, application launches are then what you would expect from roaming profiles (or even a local profile). No additional requests to the network are required, so file access is from the local disk.

Conclusion

Logon times receive top billing as time wasters for users, so we focus on getting logon times as low as possible.

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Don’t keep users waiting…

There’s nothing wrong with reducing logon times, it’s a noble pursuit, but the simplest and easiest method of doing so is to implement folder redirection. It gets data out of the profile, is built into Windows and is therefore a quick win. Everyone does it, so it must be good, right?

We’ve shown that it’s very easy to impact logon and application launch times with and without folder redirection, just by placing the file server under load. When a Windows desktop is integrated into an enterprise environment with roaming profiles, folder redirection, home drives and perhaps even Exchange mailboxes, performance of the desktop is dictated not just by the PC alone, but also the available resources of other components in a distributed network.

File server resource configuration must align with desktop requirements, but profiles and home directories grow organically, so sizing can be challenging. Monitoring and proactive management of file servers is essential.

Part Three

In the next article, Helge will cover the Windows Search and Start menu experience.