Proto Balance can perform between 1500 and 3000 new connections per second per CPU Gigahertz on all supported hardware platforms. Therefore to calculate the low bound, simply take the real CPU clock speed in GHz and multiple it by 1500.

Proto Balance can perform between 5000 and 8000 HTTP 1.1 requests per second per CPU Gigahertz on all supported hardware platforms. Therefore to calculate the low bound, simply take the real CPU clock speed in GHz and multiple it by 5000.

On x86 64-bit Unix systems (like AMD64 and Intel Core2 64-bit and later), Proto Balance SSL can perform about 400 new SSL negotiations per second per CPU Gigahertz.

On x86 64-bit Windows XP x64 Professional, Proto Balance SSL can perform about 400 new SSL negotiations per second per CPU Gigahertz.

On SPARC 64 platforms Proto Balance SSL can perform about 200 new SSL negotiations per second per CPU Gigahertz.

HP-UX PARISC 2.0 64-bit has performance in a similar range.

Proto Balance can handle 10000 concurrent connections using under 512 megabytes of RAM. Proto Balance consumes only a few megabytes of disk space.

There is none. You can have hundreds of back-end servers.

There is none. Thousands of concurrent clients may connect. There are no traffic or connection-rate limits.

The Proto Balance license is a once-off purchase that allows you to install Proto Balance on a single machine with an unlimited number of back-end servers and an unlimited number of clients. See the section "Licensing Terms".

Please contact us. We can provide bulk or organization-wide licensing on request.

Hot deployments are software deployments that incur no downtime for the client users. With Proto Balance it is easy to switch from one back-end server to another. So you can re-deploy your server machines in sequence without ever having a moment of total unavailability. The redeployment is completely transparent to the client users.

Yes. With Proto Balance you can add and remove back-end server machines even during peek load.

Yes. Proto Balance starts many concurrent threads/processes, so these will be distributed to different processor cores.

A hardware load balancer is a dedicated network appliance that performs packet routing at the Ethernet or IP level. Proto Balance is more suitable than a hardware load balance for most applications because it provides more comprehensive and controlled monitoring of the boxes in your cluster. Proto Balance also runs on all popular platforms, which are easy to upgrade, or replace in the event of failure.

Proto Balance is available for the following systems:

Contact us to request support for other platforms.

Any service running on a box should receive or send at least one byte of data before closing the connection. If a connection error or close occurs before 1 byte of data has been transferred, then the box is deemed to have failed.

Note that HTTP protocols (included "Soap", "Web Services" and ordinary web) return "500 Internal Server Error" and "503 Service Unavailable" when the server is overloaded or undergoing maintenance. In this case the client is NOT redirected to another box. (For Proto Balance to redirect would require that it cache the entire HTTP request - which could be large - and resubmit it to another box.) The client is served the 500 or 503 error as any ordinary web page. The 500 or 503 error is however detected by Proto Balance and Proto Balance fails that box. The box traffic light goes to red status immediately. The "Last fallover" message in the box configuration will show this HTTP error message.

If you get the error "No such file or directory" when trying to run the installer, and you are using a 64-bit distribution of Linux (such as Ubuntu-x86_64) then you need to install the 32-bit compatibility libraries. The Ubuntu/Debian package is "ia32-libs". Simply type "apt-get install ia32-libs".

The Nagle Algorithm queues short TCP packets and merges them before sending. This can increase communication latency and is inappropriate for a load balancer. Proto Balance disables the Nagle Algorithm.

See the section "Multiple Clusters".

Proto Balance has no limit to the number of clusters, and should scale to thousands of clusters. However, testing has only been done with a small number of clusters hence please proceed with caution.

There is no limit to the number of boxes that you can create per cluster. However, testing has only been done with a moderate number of boxes. Proceed with caution over 200 boxes in total.

Proto Balance has no known bugs, memory leaks, or other resource leaks. It should run indefinitely under all the platforms on which it is supported, provided that its operation does not exceed configurable or inherent OS limits. The MTTF is therefore that of the hardware and OS platform under which it is running.

See the section "X-Forwarded-For HTTP header" under "Advanced Options".

This refers to the feature "remembering the client IP4/IP6 address" as used on Unix systems. With this feature enabled, Proto Balance has memory space for recording the access of 1.5 million clients. Versions of Proto Balance before 200 do not expire these entries. If you expect more than say, 1 million, unique IP addresses visiting your site then do not enable this feature. Instead, see the section "Box affinity" in the user manual, and enable "Box determined by hashing the client address" - this will have a similar affect and ensure that clients do connect to the same physical machine each time.

Versions of Proto Balance after 200 (Proto Balance Advanced and Proto Balance SSL) expire the oldest clients from memory according to configurable parameters. See the Info tab in the configuration web page.

You may also increase shmmax over 128 megabytes, see "System Settings for High Performance" in the user manual. A value of 134217728 is recommended, but can be increased to 268435456 or 536870912 if your operating system allows it, and if your machine has sufficient physical memory. Remember that you need at least twice the physical memory as the value of shmmax.

Note that the option "-pthread" does not use shared memory, therefore has no such limitation. Also, the option "-shared mmap" is limited by other parameters.

The shared memory keys are from 27920 (0x6D10 in hex) to 27936 (0X6D20 in hex). The semaphore lock key is 49565 (0xC19D in hex) to 49571 (0XC1A3 in hex). These are not configurable.

You should NEVER terminate Proto Balance with signal 9 (KILL or SIGKILL). Termination can be done with any proper terminating signal such as TERM, QUIT or INT (SIGTERM/SIGQUIT/SIGINT). Alternatively, go to the "Info" tab of the Proto Balance configuration web page and click on "Force balancer to shutdown".

Proto Balance makes efficient use of your OS, however operating systems vary in performance. Proto Balance should saturate your network interface if it is at all possible to do so in user-space for your hardware+OS combination.

At very large numbers of concurrent connections, Proto Balance total throughput will be degraded. This can be quite pronounced on certain operating systems.

This means either that Proto Balance is already running, or that another application is listening on this port. If there is another application using port 8080, you will have to stop it first. Try un-installing any Web Service, Oracle, and application-server software.

Otherwise you can use the -configport option as explained in the Proto Balance top-level window.

You are running out of certain TCP resources. Follow the instructions under "System Settings for High Performance with Your Operating System".

None. Proto Balance is an ordinary user-space executable.

Besides the performance testing above, Proto Balance has been run for hundreds of hours continuously at network-saturation load. Proto Balance has been verified under memory profiling tools such as Valgrind and Purify. Proto Balance incurred no errors or warnings by either of these tools and had flat OS resource consumption.

The Proto Co Networking team uses an internally developed TCP-scenario automated test harness, and on-site hardware for all supported platforms.

Proto Balance is self-monitoring with over 750 different internal consistency tests.

This product includes software developed by the University of California, Berkeley and its contributors.