This topic includes information you need in order to accurately size your Shared Ethernet Adapter environment.
To plan for using Shared Ethernet Adapters, you must determine your network needs. This section gives overview information of what should be considered when sizing the Shared Ethernet Adapter environment. Sizing the Virtual I/O Server for the Shared Ethernet Adapter involves the following factors:
The primary consideration is determining the target bandwidth on the physical Ethernet adapter of the Virtual I/O Server. This will determine the rate that data can be transferred between the Virtual I/O Server and the client logical partitions. After the target rate is known, the correct type and number of network adapters can be selected. For example, Ethernet adapters of various speeds could be used. One or more adapters could be used on individual networks, or they could be combined using Link Aggregation (or EtherChannel).
The type of workload to be performed must be considered, whether it is streaming of data for workloads such as file transfer, data backup, or small transaction workloads, such as remote procedure calls. The streaming workload consists of large, full-sized network packets and associated small, TCP acknowledgment packets. Transaction workloads typically involve smaller packets or might involve small requests, such as a URL, and a larger response, such as a Web page. A Virtual I/O Server will need to frequently support streaming and small packet I/O during various periods of time. In that case, approach the sizing from both models.
The MTU size of the network adapters must also be considered. The standard Ethernet MTU is 1500 bytes. Gigabit Ethernet and 10 gigabit Ethernet can support 9000-byte MTU jumbo frames. Jumbo frames might reduce the processor cycles for the streaming types of workloads. However, for small workloads, the larger MTU size might not help reduce processor cycles.
Use threaded mode when virtual SCSI will be run on the same Virtual I/O Server logical partition as Shared Ethernet Adapter. Threaded mode helps ensure that virtual SCSI and the Shared Ethernet Adapter can share the processor resource appropriately. However, threading increases instruction-path length, which uses additional processor cycles. If the Virtual I/O Server logical partition will be dedicated to running shared Ethernet devices (and associated virtual Ethernet devices) only, the adapters should be configured with threading disabled. For more information, see Processor allocation.
Knowing the throughput capability of different Ethernet adapters can help you determine which adapters to use as Shared Ethernet Adapters and how many adapters to use. For more information, see Adapter selection.
You must determine how much processor power is required to move data through the adapters at the desired rate. Networking device drivers are typically processor-intensive. Small packets can come in at a faster rate and use more processor cycles than larger packet workloads. Larger packet workloads are typically limited by network wire bandwidth and come in at a slower rate, thus requiring less processor power than small packet workloads for the amount of data transferred.