Performance
The MTP/IP networking technology that transports data for ExpeDat is designed to adapt to a wide variety of network circumstances. The default settings will allow you to use the full available resources of your network while still being fair to other traffic.
If you are not getting the perfomance you expect, read this section carefully or contact technical support.
Refer to DEI Tech Note 0003 for important tips on conducting accurate and meaningful performance tests. If you are considering use of a network emulator, see Tech Note 0022 for important information about emuluators.
Tech Note 0009 provides even more details about specific devices and factors which may degrade network performance.
The sections below summarize the network and data storage factors most likely to affect ExpeDat, and describe techniques for increasing or decreasing ExpeDat's speed.
Most Wide Area Network paths involve hundreds of different components, any one of which may be limiting your available bandwidth. Here are a few of the more common types to consider:
ExpeDat cannot move data faster than the slowest of these capacities. Rate-limiting devices, especially firewalls, emulators, and routers, may not be treating all traffic equally! So if performance is not meeting your expectations, check your systems for the types of limitations listed above. DEI Tech Note 0003 offers detailed advice on testing and finding network limitations.
In some environments, filesystem bottlenecks can severely limit performance. This is particularly true for network attached storage. Below are some tips for optimizing storage performance:
Any time the total network throughput may be faster than about 100 megabits per second or you are using any form of network attached storage, you should investigate your filesystem's I/O capabilities.
Normally MTP/IP makes an effort to allow other traffic on the network a fair share of available resources. If you want your ExpeDat data flows to achieve the absolute maximum speed, regardless of other users, you may do so by increasing the network "aggression" of MTP/IP.
Aggression affects relative performance compared to other data flows sharing the same network path. If there are no other data flows, or if the hardware is already operating at maximum capacity, then increasing aggression may have little or no effect.
Increasing aggression when hard-drive I/O is limiting performance may actually reduce throughput. If you suspect that your hard-drive is the bottle-neck, try a aggression setting of +2 or less.
Aggression is a value between -3 and +5 which determines how hard MTP/IP presses the limits of the underlying network hardware. Default values are in the range of 0 to 2 (depending on your license configuration) and try to strike a balance between speed and fairness. Setting a higher aggression level of 3, 4, or 5 may improve ExpeDat throughput, but it may also be disruptive to other users of the network.
Carefully read and understand the following paragraph before using aggression level 5.
Aggression level 5 should only be used if your entire network path fully supports large UDP datagrams (frame sizes over 1500 bytes). For example, if you are operating on a gigabit or faster ethernet LAN and have Jumbo MTU enabled, you may find that level 5 allows you to fully utilize the network while reducing your CPU load. However, if any component of the path does not properly implement IP fragmentation standards, this level of aggression may cause severe performance degradation or even a loss of connectivity.
Certain high-security encryption and VPN devices are known to misbehave in this way. Some consumer grade or low-speed DSL and cable modems also may have problems with high aggression. You should carefully test aggression settings above 2 prior to deployment.
Refer to each component's documentation for instructions on setting aggression.
For shared network environments, you may wish to limit ExpeDat's impact on other users even more than the default settings.
The most flexible way to give priority to other users is to reduce the aggression level described above. Values below 2 will limit the resources MTP/IP is willing to use, leaving more resources for other traffic flows. Note that on networks with inherently high-latency or packet loss (such as satellite or packet radio), lower aggression may reduce performance even when there is no other traffic.
Aggression affects relative performance compared to other data flows sharing the same network path. If there are no other data flows and the network path is "clean", decreasing aggression may not have an obvious effect on performance. But it will still cause performance to slow down in the presence of other data flows.
You can also set a specific bandwidth limits for ExpeDat. The MaxRate settings can be used to establish speed limits for both individual transactions and the server as a whole. If your data path has a fixed known capacity, you can set MaxRate to a value less than that to apportion the bandwidth between ExpeDat and other users. You can even combine this with increased aggression to make ExpeDat use exactly that amount of bandwidth.
If you have applications on your network which are sensitive to latency issues, such as voice or video over IP, you can set a specific latency ceiling for ExpeDat. The MaxRTT setting will cause MTP/IP to slow down whenever it observes latency above the given value.
MaxRate and MaxRTT work best in WAN environments. On LANs, or paths with latencies of only a few milliseconds or less, they may not be accurate.
Refer to the links above for details on how to set these values. Also see DEI Technical Note 0005 for general information about MTP/IP bandwidth management features.