QoS for Virtual Environments

Arthur Cole

Arthur Cole spoke with Ravi Chalaka, vice president of marketing, Neterion.


Cole: Providing QoS on the network level is a rather new concept. Can you explain what it means?
Chalaka: When we say QoS in a network environment, we're talking about the ability to provide different priorities to different workloads as a way of guaranteeing appropriate levels of bandwidth, availability and security. In the past, this was not an issue because you had a single server with only one application or major operating system. Now, in a virtual server, you may have Oracle, SAP, Exchange, etc., all in a mixed environment.


So far, the alternative has been a dedicated NIC card for a single VM when you want guaranteed service and availability. When you have two or three VMs, this is OK. But when you get past seven or eight-and some people are already planning on 40 or 50-this becomes a congestion problem because you have to put multiple adapters on multiple cables. How are you going to manage all that cabling?


Cole: Won't this problem go away with the new high-speed technology coming out?
Chalaka: Most 10 GbE systems have been about throughput and performance. This is important, but it doesn't solve the problem of quality. When you have seven or eight workloads and one is simple FTP data that is blocking the data path, more mission-critical applications may have to wait because of the first-in/first-out environment in most networks. So even though you have more bandwidth, you'll still see congestion, bottlenecks, degradation and poor overall responsiveness of mission-critical applications.


Cole: How does the IOQoS system address this?
Chalaka: IOQoS allows the adapter to reserve resources and allocate bandwidth by priority level. Higher-priority traffic automatically gets the maximum line rate. Switches and routers already do this, but the weak link has always been the adapter. We eliminate this problem at the I/O level so you can prioritize data flow within the server.


This also helps further I/O virtualization because you can treat a single adapter as a multi-adapter. If you have truly independent I/O channels within a single adapter, you can consolidate cabling, heat control, management and other elements into two adapters at most, depending on how many applications you are running.

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