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LTSR1912 CU1 slow file reads from redirected network drives



one of our .dotNet based application running on LTSR1912 CU1 Windows 2019 VDA suffers from very slow file reads through redirected network drives and ICA channels.  Even files as small as 1-2 megabyte take longer than default 100 .dotNet seconds http library timeout resulting in failed file uploads.  The application is published in US based datacenter and the issue affects mostly users in Europe with network drives mapped to file servers located in Europe datacenter.   ICA latency and ICA RTT as reported in Director do not exceed 100 ms with 200 Mbps bandwidth.


The same user from the same location running exact same application on XenApp 6.5 RP7 Windows 2008 R2 works just fine with only few larger files fail uploads due to taking longer than 100 seconds to complete transfer. 


The VDAs have been optimized by running and applying CitrixOptimizer 2.7 Windows Server 2019 build 1809 from Citrix (Recommended) OS optimizations. 

Disabling bandwidth throttling, enforcing Use Asynchronous writes and increasing outbuffers didn't help.


Is anyone aware of OS or VDA specific tweaks that may help resolve slow reads issue in my scenario ?


Any help with this will be highly appreciated.


Thank you. 



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Try setting the Read & Write Cache on the VDA:

     Set-ItemProperty -Path 'HKLM:System\CurrentControlSet\Services\PicAdm\Parameters' -Name EnableCcReadCache -Value 1

     Set-ItemProperty -Path 'HKLM:System\CurrentControlSet\Services\PicAdm\Parameters' -Name EnableCcWriteCache -Value 1


You can also change the Packet Integrity Checks per CTX231205 but we didn't need to mess with that to fix our slow transfers. 


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