Buying pre-assembled servers is expensive. Often small operations like TheKats.com cannot afford high-priced servers from companies like IBM, HP, or Dell. There is, however, a lot of mileage to be gotten from building your own small servers. Low to moderate cost, only the features you need, and best of all, over the counter parts means that you are not beholden to a manufacturer to get a replacement (more expense.) The down-side, of course, is that you're on your own to provide support.
My thoughts in starting this discourse, is to build a foundation platform for servers that can operate as web servers, DNS servers, moderate-duty database servers... Additionally, since TheKats.com runs Windows 2000 servers, I'm not looking at the support for LINUX/BSD on these platforms (is all the hardware supported by LINUX/BSD), though that makes the most sense cost-wise. Hopefully, someone will contact me with information or alternatives to my platform to be more LINUX and/or BSD friendly.
A case, motherboard, CPU, memory, video, LAN, hard drives. That's the basic collection of things that are needed. We'll expand that a little bit as we discuss each one.
What about a floppy disk and CD/DVD-ROM? USB attached floppies, CD-ROMs, and hard drives can get your O/S loaded and your server on the net. Leave floppies in the dark ages where they belong.DVD-RWs, particularly the dual layer (DL) variety are perhaps worth the little bit of money to incorporate as they can be used as an in-server backup device if your content is less than 8GB.
Frequently, this is one of the hardest decisions to make. It, as much as anything is predicated on the server's role and environmental requirements.
First, will this server be rack-mounted? If "yes", then we've racheted up the cost and the constraints. (This is the configuration we're going to look at.) All of the parts for a rack-mount case will work in a standard tower or desktop case. If space doesn't dictate that a rack mount case is a requirement, then you can save some money here.
Rack mount cases are designated in U's (rack units.) One (1) rack unit is 1¾" in height. The number of U's tall your case is will largely determine how much "stuff" you can put in it. The smaller the number of U's the less space each server will consume.
1U cases are cool, but have significant issues. First, is that they don't hold much stuff. They also require special power supplies (expensive) and CPU coolers (expensive.) You also have to be very careful of the thermal issues. Most of these cases are going to require a battery of 40mm fans, making them loud.
2U cases are ideal for my situation. My web servers don't need a lot of fancy storage, so the limitations on how many disks can go in these cases isn't an issue. (Although with 500GB SATA drives, you can put a lot of storage in 2 drives!) I have enough servers that jumping to 4U is a bit painful. They take standard power supplies and the retail heatsink/fan combos from AMD and Intel fit just fine. At 3½" tall, they allow me to have room to add more in the future. One of the downsides of 2U servers is that standard PCI cards will not go in their standard vertical positions. 2U cases come with a riser card to accomodate 2-3 PCI cards; rarely AGP. This pushes the desire for an integrated (VGA and Ethernet, hopefully RAID, included) motherboard.
3U cases are an odd duck. Few manufacturers make them and therefore, they tend to be expensive. Personally, I wish this wasn't true as it seems the perfect size for me. It is the smallest case that PCI cards go in their normal orientation. But the expense dictates 2U or 4U.
4U cases are probably ideal for most people. The least expensive of the rack mount cases, they take PCI cards in their standard orientation so you can use any motherboard. Potentially more room for storage, but you have to be careful. Some of the least expensive ones actually have very poor layouts and little room for storage. Go for this size if you have more storage needs or a more challenging thermal situation.
Larger? There are quite a few larger cases, or ones with integral hot-swap bays for SATA or SCSI. You can easily spend a lot of time making a case decision. Just remember the more features there are the more they cost.
Here's is the path to less expense. If you have the room to use a standard tower (mini-, mid-, full) or a desktop case, they can be had for much less money. Just try to determine the storage or expansion needs ahead of time. Mostly this comes down to how many hard drives you want to put in it.
Since I'm targeting a 2U case, I'm interested in an integrated motherboard to make life easier.
Since video performance isn't an issue with a server, we could go with a non-integrated board and a PCI video card in the riser. Checking eBay showed over 1000 hits when searching for "PCI" and "video". Some for as little as a penny. The same is true for network cards, and we'll revist that topic further down.
Personally, if an integrated board is available, I like to use that. Fewer parts, sometimes an integrated mobo/video driver, less to interfere with the airflow through the box.
There are "server" motherboards. These boards often have the video and 2 LAN connections built in. They sometimes add a 2nd CPU socket, SCSI, RAID, and advanced health monitoring. These are all cool, but have a price. Usually greater than $200 just for the motherboard.
I like AMD CPUs. When you compare price and performance they appear to be the smart choice. Add in the fact that 64-bit potential is there in the Athlon 64 and is there anything more you could want? Some people are committed to Intel. No problem. We'll look a little at those, too.
There are two (2) basics to matching CPUs and motherboards: socket type and bus speed. Get these right and usually your combination will work fine. Of course checking the motherboard manufacturers website for a CPU combatibility list is recommended.
Currently, you have a choice of the AMD Sempron (32-bit) and AMD Athlon 64 and X2 (64-bit) processors. Ok, so there's Opteron, too, but we're looking at low-cost, and Opteron's require higher priced server motherboards and are only an advantage in multiple CPU configurations. Since AMD came out with the Athlon 64/X2 processors going dual Opteron has become less attractive. Price eliminates it from our consideration.
Ok, I've got too admit that Intel has me confused. How many different processor types do you need?