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Slowness and Freezing experienced when theres lots of read/writes to file server

Have bumped into this problem a couple of times now and it is very difficult to troubleshoot.
I saw this recently after a new application went onto a Citrix server with 25 concurrent users.
They had number of applications that were reading and writing to a file share (Lotus Notes data in particular),and they were also using a redirected %appdata% to the file server which meant any apps that use the appdata folder for configuration information (most) were also reading and writing to the file server very frequently.
There is an OS limit of 50 concurrent outstanding network requests between a Server Message Block (SMB) client and server, which can be overrided by a couple of registry settings.

You can use the following performance counters to troubleshoot the issue:
Server\Files Open
Server\Server Sessions
Server\Work Item Shortages


Fix
Create the following DWORD registry keys if they are not already there and set the value to 2048. This should be more than enough for any Citrix Server.

On the file server:
HKLM\SYSTEM\CurrentControlSet\Services\LanamanServer\Parameters\MaxMpxCt

On the client/citrix server:
HKLM\SYSTEM\CurrentControlSet\Services\LanamanWorkstation\Parameters\MaxCmds

See the following MS articles for more info:
http://support.microsoft.com/kb/810886
http://support.microsoft.com/kb/232476


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