Drive redirection cache

This topic explains the Enable drive redirection cache option, which is available in a dialog where you configure RAS RD Session Host, VDI, Azure Virtual Desktop, or Remote PC agents. When the option is enabled, browsing folders on redirected drives becomes much faster thanks to the caching mechanism explained below.

Native RDP is not efficient for file and folder enumeration when using drive redirection, which results in slow and sluggish user experience. The Enable drive redirection cache option forces the session host to run the kernel-based driver (RasRdpFs). This optimizes how the communication is carried out compared to standard RDP and also adds caching of the folder structure on the session host (RDSH, VDI, or Azure Virtual Desktop). The driver starts as soon as the setting is pushed to the session host via Apply in the RAS Console. When this happens, all new sessions will have this functionality enabled. The existing sessions need to be reconnected to use this optimization.


  • A session host must run a 64-bit operating system.

  • The cache is per session and is paged into the driver memory.

  • On log off or disconnect, the cache is purged.

  • If the number of cached folders in the session exceeds the threshold, and the user accesses a new non-cached folder, then the oldest accessed folder is replaced in the cache.

  • When the option is switched off, all currently active user sessions will lose the cache (the driver is stopped and the cache is purged). This happens transparently to the user, but file and folder enumeration become slow.

  • When the option is switched on, all currently active user sessions will not automatically have the cache enabled. To use this functionality, the existing sessions will need to be reconnected.


  • The option is applicable only to sessions initiated by the following versions of Parallels Client:

    • Parallels Client for Windows versions 18 and later

    • Parallels Client for macOS versions 19 and later

  • Similar to native RDP changes made on the client side (in a remote session), requires manual refresh (F5) in a redirected folder on the server side.

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