IBM Virtual Desktop
Supplying users with virtual desktops addresses some issues
But there are some “gotchas” that you need to consider
By Budi Darmawan
Virtual Desktop Infrastructure is an attempt to provide enterprise wide employees a unified, managed environment for their workspace. The virtual desktop allows each employee to have his or her desktop system within the datacenter (i.e.: in the cloud), while they connect to it using a secure connection from their pervasive devices such as smart phone, tablet, laptop or home computer.
Virtual Desktop and Cloud
The virtual desktop infrastructure is quite similar to a cloud system. Both rely on virtualization of hardware and software and both will benefit from the sharing of resources in the datacenter and integrated management from the datacenter. However, due to their workload profile, there are significant differences.
The following lists the difference in the workload profile for virtual desktop against a more ‘traditional’ cloud or virtualization:
· Number of users: Virtual desktop is used by ALL employees; it is being used for the employee’s interactive day-to-day workload. Traditional virtualized cloud is mainly used as a special-purpose system, such as application servers, or test environments.
· Load type: Virtual desktop load is mainly interactive, made up of things like mouse clicks and screen refreshes, with occasional disk access, per user. These activities increase network load. Virtualized cloud for servers is mainly offline background work which puts the burden on CPU and memory.
· Active time: Virtual desktop is mainly active on prime shift when employees are working, so for a follow the sun operation, load sharing can be performed for different shifts and locations.
· Base system: Virtual desktops are usually more uniform than traditional test or server environments; corporate IT departments have standards on what employee can run.
Issues to consider
Virtual Desktop implementation on a standard cloud system would generate some issues due to the above load profiles.
· One of the main problems on early implementation of virtual desktop is disk access for multiple users. This access does not scale linearly. One of the measurements of this is called IOPS (Input-Output Operations per Second); as different users access different part of the physical disk, and each of the desktop environment can be hosted on different area of the same disk, they will eventually compete for disk access. The latency for this would increase exponentially as more contention arises between different users.
· Branch office users would generate network traffic for mouse movement and screen refreshes that competes with actual production (money-making) transactions. This eventually can present a bottleneck in the Wide Area Network (WAN) infrastructure of the enterprise.
· Idle capacity as the users leave their virtual desktop open (not switched off) but not being used. This creates a processing overhead that may impact system-wide performance.
Addressing the issues
Depending on the issues, several alternative methods have been developed to address them.
· Due to the uniform nature of the image, the number images for virtual desktops can be easily shrunk down to a small set of corporate images.
· Smart buffering of images in memory can significantly reduce the IO contention for high number of users. The buffering, coupled with the fact that there is a limited set of corporate images, allows (with enough resources) images to be completely stored in memory, reducing all read operations and batch performing the write operations.
· Creating branch-level servers which also cache the virtual desktop images, provides user interface operations locally. This will significantly remove the WAN network pressure.
· Detecting idle sessions and shutting them down in an automated fashion will help on alleviate overhead from systems that are not properly released after the employee disconnects.
Building the solution
Some significant requirements for the Virtual Desktop Infrastructure include:
· IO optimization
· Platform support (for the desktops)
· Secure access
IBM Virtual Desktop supplies the solution for the above requirements. It has uniquely designed storage optimization that allows most of the virtual desktop to run from a copy in memory. This reduces the desktop user IO requirements significantly. With the avoidance of IO needs, IBM Virtual Desktop provides significant scalability compared to having an individual, dedicated disk for each desktop user.
IBM Virtual Desktop supports both Windows and Linux based desktops and therefore allows portability between the different desktop platforms.
For more information on IBM Virtual Desktop, refer to:
Budi Darmawan is a Senior Technical Enablement Specialist with IBM Software Services for Tivoli. His areas of expertise include TSAM, ISDM and Smart Cloud Orchestrator. He has been with IBM since 1990 and has written more than 40 IBM Redbooks. He lives in Austin, Texas.