Slashdot Mirror
Can My Desktop Make It in the Big Leagues?
bionic-john wonders: "I work in an environment where the dollar is more than almighty (who doesn't?). One of my cost savings plans is to use desktop computers as servers. They cost much less, the parts are readily available and/or interchangeable - as opposed to waiting for overnight proprietary or obscure parts from a vendor, and so on. I understand that servers have redundancy on disk and power - but this can be emulated for a fraction of the cost, as well. Is there a performance difference between a desktop and a server with the same specs? Chipsets are chipsets, motherboards are motherboard, and memory is memory -- is there something special about a server other than looking at the rack of blades and feeling special?"
If you don't have much space to spare, I would go with rackmount servers anyway. Some also provide remote administration capability separate from the OS, meaning you can reboot it and such.
US businesses that currently accept chip and PIN/signature
- Disks fail. When you stick a server in a rack and leave it running for 5 or 6 years (unlike your average /.'ers desktop which probably gets a shake-up far more often), you won't regret being able to hot-swap a failed drive on your RAID array with a spare.
- Power supplies fail... To be honset, this isn't nearly as big a deal in the hot-swap arena as the hard drives. However, having 2 power supplies in a server machine means that things are significantly less bad when or if one of them happens to fail.
- Vendor commitment. From those old Compaq Proliants to the new Dell Poweredge machines, they were built to be stuffed in a rack and left untouched (unless something fails... see above). They'll come with hardware that those vendors usually stake their reputation on or even had a hand in building. Even the management software isn't always bad....
Bits of experience form my days of administrating a heterogenous network of desktops-as-servers in an ISV shop (disclaimer: I am professional software developer, I did administration because I was most knowledgeable OS geek). Several reasons why you don't want dektops to be servers: * Power supplies. Beleive me, PSUs DO fail. And more hosts you have the higher probability of failure you get. Even if you keep a stock of PSUs in the closet. It still takes you about 20 mins to get desktop/server up and running again, and night failure is far worse. * Rack mounting is not a vendor trick to charge you more money. If you have more than trivial infrastructure, wiring on desktops and "floor-tops" is going to be your favourite nightmare. * SCSI and SCSI raids are just a waste of money on a desktop but it is must have for intense, parallel access of many users to their homes, mailboxes, whatever on server. * not last and not least: having someone working on a server is probably most stupid idea in the whole IT. Whatever OS you use, beleive me, users will find a way to devour 98% CPU time and 99% of memory. That leaves for server applications.. well .. do the math :)
There are many other things, I just came up with whatever came into my mind right now.
my sstream of consciousness
What makes this guy a server? I'm no expert, but here's what I see:
- Lots of RAM. Came pre-configured with 1GB, and could handle many times that.
- There's only two 32-bit PCI slots, but four 64-bit slots. Handy if you want to add RAID or Fibre support, a nuisance if you want the more ordinary kind of add-in.
- No built-in sound card.
- No AGP interface. Instead, there's a basic 4MB video interface on the motherboard.
- Massive fans.
Anyway, bionic-john is correct in thinking that a workstation will do as a server, provided only that you don't demand more of it than it's designed to do. (Which is always a question anyway.) I work for a hosting/colocation provider, and I see all kinds of stuff pressed into service as servers: cheap white boxes, Sun and Apple workstations, even an X-Box or two. Ultimately, all computers are interchangable. Specialized computers are just a matter of convenience and cost-effectiveness.Reliability is the only difference between a desktop and a server system. If you can tolerate an outage every few weeks, go ahead and use desktops. If you need 100% uptime, get a real server, it will pay for itself many times over.
What if a hard drive dies? In a server, you pull it out, pop in a new one, and the RAID array fixes itself. The users don't notice a thing. In a desktop machine, you have to turn it off, unplug everything, open the case, unscrew the screws, unplug the cables, remove the drive, put in the new drive, put everything back together, restore the array manually, and hope you didn't lose some data. And all while you do this, the server is down and nobody can do anything.
Just keep one thing in mind. If you pay too much, nothing will happen. If you get a crappy system, you will get fired.
Buy quality parts, and everything should be OK. Don't expect a $300 emachine to last out the year.
A few tips:That said, dual CPUs and rackmount cases are a luxury, and if cost is that important, you can skip them. And make sure there is a process in place to check on the health of the server. Even waving your hand behind the box once a week to check how hot the PSU exhaust is can save the business a lot of headache. (Hint: if no air is blowing, replace the PSU, and check the HDDs to make sure they're both still working.)
Also, be wary of Dell. They use non-standard power supplies, so if your PSU goes out, you can't hop down to the local computer store and buy a replacement.
RAID 0 is striping. RAID 1 is mirroring.
This is how most IT departments start, and it's a normal process of evolution.
... or it may not. I have seen a couple of
In the beginning, there isn't much money available, so most places cobble together 'servers' from spare desktop components, and throw them up in a closet somewhere. That generally works okay, and the company realizes that they like having servers, so over time, the installation grows.
As it gets bigger, the lower reliability of desktop components will start to become apparent; servers will go down, hard drives will fail. It's just statistics; given enough samples, the lower quality of the cheaper components will start to make itself felt.
Gradually, as IT departments grow, they tend to migrate towards better and better hardware. The really big outfits tend to use Dell and Compaq. Compaq in particular sells very, very expensive machines, which are very well engineered and hardly ever break. But you pay through the NOSE for this kind of service.
So how do you know how much to spend on your servers? When you gain the ability to numerically measure how much it costs you when they fail. When your department and company mature to the point that you can accurately measure costs of downtime, then with management's decision on acceptable risk levels, you'll have a pretty good idea of what you should be spending on servers. Many big companies find that the cost of downtime is appalling, when they actually are able to measure it, and that the cost of even very expensive servers is minimal in comparison, so they buy the best stuff they can find.
But until you can measure it, IMO you're fine with desktop components, as long as you buy GOOD ONES. Don't skimp on your drives, and make sure you have good cooling for them. Buy server cases; you can get good ones for a couple hundred bucks that will hold a billion drives, and then make sure to buy good cooling; you may want the boxes that mount 3.5" disks in 5.25" slots, with fans and hotswappability. I usually buy PC Power and Cooling power supplies for servers; even the Silencers are fairly loud, but they are very robust and well-built. Many of them are dual supplies in one box, which improves reliability even more. That's a lot of fans in each machine, so you may want to pick up a spare or two with each machine you buy. (Tape them inside the case). And the noise level, particularly once you get a number of them, will be high... but think of it as the sound of reliability and you won't mind it too much. Also note that when you get past a few machines, or if you spend a lot of time in server rooms, you should wear ear protection. I have worked in big colo facilities that were absolutely deafening, to the point that things sounded muffled when I left. That kind of noise DOES DO DAMAGE, and you want earplugs.
Make sure you understand exactly what onboard network chipset you are buying: you most likely want an Nforce3 or an Intel, um, 865 or better, I think it is... where the network card is directly on the northbridge, so you can get the true gigabit speeds. When they are on the Southbridge, and look like they are PCI devices, you can't run gigabit full out. And never buy a motherboard that uses Realtek 8139 networking, they are garbage. They make the CPU work way too hard, and are NOT good for server machines.
What you will end up with is a whole room full of Frankenclones, but if you've been smart and spent your money on good stuff, it'll be almost as reliable as the Dell/HP/Compaq/IBM clusters for a tiny fraction of the price. And you'll be able to get replacement parts anywhere. But you probably WON'T have spare parts on hand to fix things, unless you've been unusually clever in your design, because each new generation of machines will be different than that last, and you won't be able to use the same replacement parts interchangeably.
Someday, when you find out what downtime costs you, the extra cost of the big label servers may suddenly look wonderful
There is no distinct line between server hardware and desktop hardware. A lower end server is easily build from decent desktop components. The bottom line is: buy good hardware.
Don't skimp on the harddrives, but go for reliable ones. SATA Raptors are as reliable as many SCSI drives, and go in any modern desktop. RAID5 them. RAID5 in software isn't much of a CPU hog in modern machines. RAID5 in hardware is faster, but more expensive. Fit to budget.
Hotplugging SATA is not really supported (tested) in Linux, but expect it to mature. When a drive fails at this moment, downtime is unavoidable. In the near future, expect this to improve.
As for the mobo, memory, network, case. Get quality stuff, but don't go overboard. Onboard vga is fine for your purposes: it will act as a server.
Depending on your needs, backup media need to be considered. Put DVD burners in the server. Backup often. When you need more storage, portable harddrives are great. You need more than one.
Most important: (stress)test your equipment before putting it to use. Most broken hardware is broken from the beginning. Failing hardware is much less likely. The biggest difference between so called server hardware, and desktop hardware is the amount of checking it had before it leaves the factory. So do that yourself.
the pun is mightier than the sword
RAID-1, you mean; RAID-0 is striping (hence 0 redundancy). And yes, anything even vaguely important should be on a RAID array in addition to backups. RAID doesn't help much when your controller freaks out or you hit a fs or user error.
Unless you're willing to trade off warranty, latency and quality against sequential transfer rate and storage, this means go SCSI.
Buy decent fans (twin ball bearing or so?) and monitor them. If noise isn't a concern, this might be a good application for Delta's more extreme fans
On a 1U rackmount, your case fans will most likely be your CPU fans too. Pair of Opterons? Fit passive heatsinks and a bunch of 15kRPM case fans, should be sorted.
Do they make those in 64GB versions now? No? I'll just use another RAID array then, thanks.
Depends what your files are and how you're accessing them; do you want to have to hit disk for every access? With a lot of clients (which is kind of the point with a file server), a lot of memory is practically a requirement.
A good kernel should avoid this, and HTT can help, but when you can get a well kitted-out 1U dual 1.4GHz PIII for under £500, why not?
My local computer store doesn't sell 1U PSU's. Dell do however support redundant ones; I'll take that over downtime while I replace a single one, however cheap/available.
Guess which ones pick up more chicks?
If they are bragging about their computers, I'm guessing neither.
Glonoinha the MebiByte Slayer