Fast login means in virtual desktop deployment. We can control how many VMs to boot at the same time but difficult to control the number of simultaneous user login.  This makes fast login even more important.

During our 2000 seats vSphere and XenDesktop reference architecture, we tested a few cases and the goal is to login 2000 users within 30 minutes.

Scenario                                                                                             Result

• With NetApp FlashCache when the cache is warm                 Pass
• With NetApp FlashCache when the cache is cold                    Fail
• Without Citrix UPM exclusion rules                                         Fail
• With Citrix UPM exclusion rules                                               Pass

Flash Cache

The test result clears some misunderstanding on the importance of NetApp Flash Cache for Citrix PVS work load. PVS write cache is mostly writes and some may think Flash Cache read acceleration is not useful. During login, there is profile read/write IOs, vDisk read IO, and write cache write IOs. NetApp Flash Cache is important for user profile read acceleration.  For FAS 2000 series when you cannot use Flash Cache, Flash pool is recommended to accelerate read and write IO.

Citrix UPM 

To make sure that the user profiles and settings are preserved after the desktops are reprovisioned from the updated vDisk (as a result of desktop patch, update and so on), we leverage the profile management software like Citrix UPM to redirect the user profiles to the CIFS home directories.

• Desktop settings such as wallpaper and screen saver
• Shortcuts and Start menu setting
• Internet Explorer Favorites and Home Page
• Microsoft Outlook signature
• Printers

Some user settings and data can be redirected by means of folder redirection. However, if folder redirection is not used these settings are stored within the user profile.

Folder Exclusion

Adding a policy to exclude the redirected or unwanted folders from roaming or synchronization is very important to reduce IO during login.  Using Citrix Profile Management, you need to add all of the redirected folders to the folder exclusion list and you should also at a minimum add the following additional folders to the exclusion list: “AppData\Local”, “AppData\LocalLow”, and “Local Settings”. Check the screen shot of CVD on HVD policy, notice the exclusion list.

NetApp recommends using a profile management solution such as Citrix User Profile Management (UPM) to allow end users to customize their experience in a nonpersistent desktop environment.

NetApp Flash Cache/Flash Pool and Citrix UPM  are essential to lower user login IOPS and login time. Also for more information on how to set profile in XenDesktop deployment, check Dan Allen’s blog: http://blogs.citrix.com/2012/02/11/citrix-profile-management-and-vdi-doing-it-right/.