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BP1018 Sizing and Best Practices for Citrix XenDesktop with Dell EqualLogic Storage 38
7.4.2 Write cache recommendations
Storing write cache on the target devices (virtual desktops) is recommended for better performance
because the file creation is local to the target and not streamed to any servers, which avoids additional
network traffic.
Restarting virtual desktops clears the cache file and it is highly recommended to restart the desktops at
least once per day or more frequently if possible. This clears the write cache area which is very critical
for optimal performance of virtual desktops.
7.4.3 Optimizing the Windows 7 master image
Because we are using provisioning servers to stream the single vDisk to all virtual desktops, proper
design and optimization of the master OS image is very critical for better user experience. There are
specific system settings and configurations which enable faster logons, reduce unnecessary prompts,
create quicker screen updates, and other conveniences. Also, Windows 7 includes many services by
default. When using provisioning services, these services do not provide any value. Provisioning
Service actually resets the virtual desktops to the original state upon reboot, so input into the services
is lost after each reboot.
We recommend using the Windows 7 optimization settings described in the following Citrix article:
http://support.citrix.com/servlet/KbServlet/download/25161-102-649933/XD%20-
%20Windows%207%20Optimization%20Guide.pdf
7.4.4 Allocate more RAM on PVS servers
It is always recommended to allocate slightly more memory to provisioning servers RAM than the base
vDisk image. The vDisk attached to the PVS servers will cache to the memory, which results in vDisk
being streamed from memory rather than from SAN. Memory access is always faster than the disk.
This approach will help to:
- Reduce the overall read IOPS on the underlying storage array.
- Allow very fast access to the master disk image which results in better user experience.
7.5 Storage
Detailed storage performance and capacity sizing guidelines are presented in section 5. Additional
recommendations are listed below.
7.5.1 Volumes and datastores
It is recommended to create at least three or more volumes on a single EqualLogic member for better
performance. Using multiple volumes helps by enabling parallel I/O from the controllers which in turn
results in better performance and manageability. These volumes host the vDisk and desktop write
cache.
7.5.2 Storage array characteristics
We recommend using EqualLogic PS6010XVS hybrid arrays which consist of eight SSD drives and eight
15K SAS drives for hosting the performance critical components such as vDisk and write cache. The
other components such as user profile information can be stored on high capacity arrays such as
PS6510E.