Main:Servers
From Servers4Linux
Servers
It's hard to quantify what a "real" server is. It's gotten particularly fuzzy in recent years, with people selling PC hardware and calling it server hardware. Maybe an example would be helpful. This is a HP rp8400 16 socket server with 16X CPU PA-8700 875MHZ CPUs and 48GB RAM MEMORY for $2900 "Buy It Now" price. I've seen similar ones for less than $1000 recently with no bids.
This server is a real server. Servers like this have the following characteristics.
Real Serial Console
"Real" servers have "real" console ports. "Real" in this case is defined as "If desired, all output at all times can be (or is) directed to the designated console port". What does "all output" mean? Well, at boot time, before the OS starts, most hardware gives you some sort of BIOS setup dialogs. You see something like "Welcome to XYZ server model 123, press F10 to configure...". In the case of "fake" servers, this output can only be seen on the VGA video output port. They may have a serial port, and the OS might be able to use it (once it starts), but the initial dialogs are VGA only. This presents many problems, usually with remote access. There are times when it is desirable to easily configure a server remotely, and this "I'm too stupid to use anything but VGA" behavior is frustrating. Real servers have both serial and VGA (older ones maybe just serial), and the administrator can CHOOSE to use either serial or VGA as they see fit. PC hardware slapped into a rackmount case typically cannot do this.
Lights Out Management
One critical difference between "real servers" and wannabe servers is their "Light Out Management" capabilities. Real servers are really 2 servers in one cabinet. There's one little embedded server, termed the "service processor", "management processor", "LOM", or some such that's *ALWAYS* on if power is applied. These usually have their own dedicated network interface as well as serial port, KVM connection, etc. The LOM card supervises the main server. You can ask the LOM for main server status, tell the LOM to power off or power on the main server, tell the LOM to reboot the main server, etc. Newer LOM cards will "redirect" the console to a web based GUI in a browser so you can *SEE THE POWER ON AND BIOS DIALOGS* remotely from a browser. That's seriously cool. That also saves you serious money, because good LOM means you don't need to buy separate KVM switch infrastructure. If you've ever had to get up in the middle of the night when the pager went off, and then drive to work to reboot some server, you'll appreciate this.
64 Bit Powerful Elegant CPU Architecture
If you were to take a formal college level class in CPU architectures, you'd soon note that they don't spend much time on Intel or Intel like x86 CPUs. There's a reason for that. The x86 architecture is the end result of series of afterthoughts and add-ons, bolted on to a relatively inelegant architecture to begin with. To CPU snobs, it's butt ugly. Yes, I suppose it works. If you are free to choose a CPU architecture, then pick a pretty one. Pretty much ANYTHING but x86.
Multiple CPU Sockets, Multiple Core Capable
Real servers are meant for large work loads. That means they need more than one CPU. Bigger servers mean more CPU sockets, and CPU sockets that will take dual core, quad core (or even more core) CPUs. It's common to find quad socket boxes that will take dual core CPUs. That's 8 CPUs to tackle your workload.
Larger servers from all the common manufacturers will scale up to LOTS of sockets. I've seen 64 socket HP servers on eBay populated with 1 GHz CPUs and lots of RAM (say 64 GB) go for $1000. Yes, a couple thousand dollars. The people selling them don't know or don't care. New, these retailed for approaching a good part of a million dollars.
Support Large Quantities of Fast RAM
Servers like this take lots of fast RAM. They'll have 12, 24, 32 or more DIMM sockets. A 32 DIMM socket box fully loaded with 8GB DIMMs would be, uh, well you can do the math. (256GB RAM). Since it's easy for the know-nothing resellers to pull RAM out of a server and sell it separately, sadly it's sometimes hard to find good deals on lots of RAM.
Multiple Redundant, Hot-Swappable Components
The designers of servers like this tried very hard to build them with no single points of failure. The example rp8400 for instance, has 6 hot swappable power supplies. You can literally yank a power supply out of a running rp8400 and stick in a replacement. No one will notice. Same goes for a wide variety of components. Some of these higher end servers allow you to "down" (power off) one expansion slot, CPU socket, or RAM bank, and you can replace a PCI card, CPU or RAM *WHILE* the server is running. Kids, don't try this at home on your PC (or your "server" from Dell).
Easy to Service, Accessible Components
Everything in these is well laid out and easy to get to. Often there's large multicolored decals on the case that shows you specifically how to access and replace all the components. Later models usually allow you to replace pretty much all components with no tools required.
Rugged Construction
Servers like this are built like tanks. Yes, they are a bit big. That's OK. It makes things easy to get see, and easy to get to. I once had to Fed-Ex a HP D 390 to Guam in an emergency (they had a hurricane that flooded their data center). When they were done with it they sent it back. On the way back, FedEx abused it. The outside cardboard box was trashed, all tore up. It literally had rubber truck tires prints on it. The server inside had taken enough G's to dislodge a power connector, but other than that it was fine.
Obvious Attention to Cooling
Servers like this are big and roomy. One benefit of this is that they allow for massive air flow. They usually have (lots) of high volume fans (hot swappable, of course). All those fans are noisy. You probably don't want one of these on your desk. (Well, I do, for the same reason I like loud motorcycles).
Rack Mountable
Servers like this are intended to be in racks. When rack mounted, they'll slide out and let you work on them with ease. Get a rack, rack mount your servers. You can get a little shorty 1 meter rack if you don't want one that's 6 foot tall.
