CONCLUSION

BackHome!/ADSM is able to take advantage of new hardware to achieve high throughput rates for backups over TCP/IP.

Aggregate data rates in excess of 5 gigabytes per hour are possible using the appropriate hardware and software setup.

Recommended configurations

The best BackHome!/ADSM configuration depends on many factors, including machine size and type and network topology. Here are a few recommended configurations:

• For backups, try to use dedicated hardware (CPU, network card) to run the ADSM Requestors and the TCP/IP stack. Sharing the network (specially on non-switched Ethernet) will badly degrade the performance;
• Always use as many requestors as possible, up to 4 in one single CPU. Try not to overload the CPU. Putting too many requestors in one CPU that does not have the available capacity will actually decrease performance. Watch the CPU queue length, it should be as low as possible.
• If you have only one controller card and you have sufficient CPU capacity (in one CPU), you are better off running all the requestors in the same CPU than split them onto many CPUs.
• You will want to split requestors when you run a machine that is either very slow or a machine that has high CPU usage for other tasks. Another case where splitting is better is when you have separate hardware available on each CPU (see later).
• Try to use compression as much as possible, especially if you are using a very fast machine, such as an S-70000;

Further increasing throughput

The Tandem architecture scales very well. It is very easy to add processors and network controllers. You could easily double the throughput rates given in this document (at least from a client perspective) by doubling the hardware resources allocated to the backup task. For example, you could run 4 requestors in one CPU with one network card and another group of 4 requestors in another CPU that runs its own TCP/IP stack and network controller.

Of course this holds true if neither the network nor the ADSM Server is a bottleneck. One way to ensure that is to use 100BaseTX or ATM networks and, if possible, independent ADSM Servers. In such a setup, ADSM Server migration features could then be used to consolidate the data once the backups are complete.