Ang, I did look at doing this but after reading the article it looks like its supported only during a migration phase or you need to be careful when managing settings for each server version. Ronnie Mixed farm. Mixed mode is not recommended by Citrix because of known and potential issues. For example, because XenApp 5 for Windows Server 2003 does not incorporate Preferential Load Balancing, all sessions are granted the same mid-range preference, whereas servers based on XenApp 5 for Windows Server 2008 can be configured to provide a range of preferences. Not all mixed mode scenarios can be tested, and so it is possible that an undesired impact will occur. If mixed mode is required, it should be used for the shortest reasonable period of time. Mixed mode requires that the administration of each version is performed by the respective consoles released with that version. As an example, if a farm consists of servers based on XenApp 5 for Windows Server 2003 and XenApp 5 for Windows Server 2008, a distinct set of consoles is required for administration because the configuration options differ for each version. This may add to the complexity of administering a server farm. Where HRP3 is installed on the XenApp 5 for Windows Server 2003 servers, this must be based on the installation order defined in the XenApp for Windows Server 2003 section. Where a mixed farm exists, a XenApp 5 for Windows Server 2003 server that has HRP3 installed should be designated with Data Collector functionality. http://www.thessi.com/citrix/xen/pdf/Technical_Guide_for_Upgrading_or_Mi grating_to_XenApp_5_10-23.pdf From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf Of Angela Smith Sent: 09 August 2011 09:23 To: thin@xxxxxxxxxxxxx Subject: [THIN] Mixed Windows OS's in 1 farm? Hi My current farm comprises of Windows 2003 R2 (x86) running XenApp 4.5. I need to add a Windows 2008 (x64) server to my existing Citrix farm. Are there any issues with mixing OS versions??? The Windows 2008 server will only be used to publish a single application. Will the 2008 server become a preferred ZDC due to newer OS version or can I safely mix OS's? Thanks Ang Visit our website : www.ltai.ie __________________________________________ Lufthansa Technik Airmotive Ireland Limited. Registered in Ireland. Reg. No. 45999. Registered Office: Naas Road, Rathcoole, Co.Dublin. Lufthansa Technik Airmotive Ireland Leasing Limited. Registered in Ireland. Reg. No. 140891. Registered Office: Naas Road, Rathcoole, Co.Dublin. __________________________________________ The information in this email and in any attachments is confidential and may be privileged. If you are not the intended recipient, please destroy this message, delete any copies held on your systems and notify the sender by return email. You should not read, retain, copy, disseminate, distribute, disclose or use this email or its contents in any way. Any such action is strictly prohibited. Thank you.