A load balancer is a device that acts as a reverse proxy and distributes network or application traffic across a number of servers. Load balancers are used to increase capacity (concurrent users) and reliability of applications. They improve the overall performance of applications by decreasing the burden on servers associated with managing and maintaining application and network sessions, as well as by performing application-specific tasks.
Tim Holloway wrote:F5 is a brand of web load-balancing device. Literally, a "black box" that you jack into the network ahead of the appservers.
Thanks for the info. I did check out some load balancing devices but the budget wouldn't let me use any, so we used Apache HTTPD in the end.
Of course, what this might very well mean is that instead of using a pre-optimized solution with Apache inside, you did the same general thing and spent the money on your labor rather than on theirs. Aren't bean counters wonderful?
A lot of the appliance devices are like that. Cisco's famous IOS is actually built on top of a BSD Unix, IIRC. Many of the other routers are powered by Linux, most famously WRT LinkSys (Cisco) devices.
While the prices on some gadgets are definitely over the top, one of the benefits is that by using a common pre-configured bundle, you can get it supported by commodity technicians and (often) a CodeRanch style community. And sometimes even the vendor will support it. (I'm looking at you, Intuit!)
It can be ironic that the same companies that cheerfully shift out people with critical internal knowledge every few years won't spend money on products that minimize the amount of internal knowledge needed. Commodity employees work better with commodity systems.
To make it even worse, we are now testing a hardware based solution after all. We found out that our firewalls (SonicWALL) have their own built-in load balancing functionality (I wasn't aware of that, I'm not a network admin). Since we already have them they've decided to use them instead of HTTPD. Of course that involves moving the servers to a different VLAN. Well, as long as it works and I have to spend minimal time on it, I don't really care.
Good case in point. Rumor has it that SonicOS is really Red Hat Enterprise Linux under the covers. Probably not using HTTPD, though, unless they really needed feature-rich services. Most likely either one of the lighter-weight servers or something that they wrote themselves.
My brother works for SonicWALL and he regularly asked me questions about Linux and shell scripts, so I can confirm that it's at least based on some Linux distribution.
On a side note, our Avaya S8700 telephone system also runs on RHEL. Linux is just everywhere