The big sucking sound caused by graphics

This is the fifth in a series of newsletters that is exploring our premise that we are returning to a new era of mainframe computing. The last newsletter began the discussion of the impact that desktop virtualization will have on the WAN. This newsletter will continue that discussion and begin our discussion of the new generation of mainframe computers.

Our last newsletter pointed out that a number of protocols have been developed to support transmitting graphics and 3D images over the WAN. One example of that new generation of protocols is the PC-over-IP (PCoIP) protocol from Teradici.

PCoIP is the display protocol used by the recently introduced VMware View 4 VDI product, which also supports RDP (Remote Desktop Protocol). A recently published document stated that, "To support the lower bandwidth typically available over a WAN, the minimum peak bandwidth required for a PCoIP connection has been reduced to 1Mbps." 

While the 1Mbps required by PCoIP to support a single user represents a worst-case situation, it does underscore the fact that a significant amount of WAN bandwidth can be required to support desktop virtualization. This means that in the worst case, a branch office that had 50 users who were using PCoIP for graphics, would require a 50Mbps WAN link. As noted, this is a worst case estimate and probably not likely to happen in many situations. It does, however, further emphasize that the WAN needed to support desktop virtualization is notably different than the WAN that supported the original era of mainframe computing.

It can be difficult to talk about the processing power of a mainframe computer of the 1960s or 1970s when today's typical desktop computer has more processing power than did those mainframes. Hence, it is important to not focus on raw processing power, but on the general characteristics of a mainframe computer. One characteristic is that as is the case with any general purpose computer, the mainframe could perform just about any task that you asked it. Unfortunately, it did not do any particular task very well. A good example of that was processing computationally intensive, communications processing such as terminating the WAN links. To make up for that deficiency, vendors implemented devices called a Front End Processor (FEP). The role of a FEP was to offload this processing from the mainframe and allow the mainframe to do what it was designed for – process transactions.

In the new era of mainframe computing, the FEP is an application delivery controller. It offloads computationally intensive tasks from servers and optimizes transmitting data over the Internet. As we will explore in subsequent newsletters, the role of the ADC is likely to increase as the dynamic movement of virtual machines becomes more mainstream.

Our next newsletter will be the last in this series. It will examine an example of the emerging generation of mainframe computer. The newsletter will also refer back to the first newsletter in this series which referenced Snow White and the seven dwarfs and will show that the new environment is likely to be populated by four behemoths who are beginning to really dislike each other.

Copyright © 2010 IDG Communications, Inc.

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