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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?"
- 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....
More details here.
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.well - it turns out that one of my white box servers crapped out on me moments after this article! I do not feel bad, nor do I feel like it should have been a 'server' quality machine. The machine was in fact a 1996 PII, it may have even been a cyrix. $200 later and a couple hours, I rolled out a new PIII-1000..the downside was working on SAT.
The load that these machines take are not much more that what that PII could handle (in fact I think that load handled everything great other than its nightly data mirror)..and the 'MISSION CRITICALITY' -- well that is debateable - I agree with the other poster that 2 for the price of one is a great deal (rough cost estimates, but it is close)
I can see a couple servers in the organization that are mission critical (web/mail) - but for some of the print/file servers - like I said, these little white boxes kick ass running a hybrid linux distro.
Yes - there have been times where PSU's died - but that was probably my own fault - maybe I should replace them yearly? In fact - a couple of the boxes have over a year of uptime - they just crank.
I appreciate your input on all this
PS = a lot of talk about RAID - dont forget there are some great IDE and SATA RAID cards out there - I use a few myself.
I've been running cheap desktop units as servers for email, http and win shares for 5 years. No problems. Just buy decent power supplies, check that all the fans are turning once in a while, and change out the hard disks every year or two.
"Eve of Destruction", it's not just for old hippies anymore...
It's not officially a Good Idea, but is fine for some environments.
Just take into account that server and desktop hardware are designed with different goals in mind. Server hardware is meant for 100% uptime, even in the case of most hardware failures, and have good scalability under high loads, while desktop hardware aims to give you the best bang for your buck, understanding that your data is typically much less valuable.
I'm guessing you'll be using IDE drives.
Some of the more expensive (usually scsi) hard disks and controllers have a battery backed cache that can ensure that your writes are preserved in the event of a power loss. The lack of this requires you to sacrifice a great deal of write performance if you wish to ensure integrity. The sacrifice is a bit less if the hard disk preserves write order, which ensures integrity to the extent that the filesystem is capable, though you'll still lose data. Combining a desktop ups with a desktop server, set up to power down safely before the ups runs out and come back up afterwards, is sometimes enough to let you sleep some nights.
The mtbf (mean time between failure) ratings for hard drives intended for desktop and server use are calculated differently. For servers, a consistent high load is assumed. For desktops, a low load and lots of sleep time are assumed. So a 1 million hour server HD might be equivalent to a 2 million hour desktop HD, and most desktop HD's are rated at like 300000 hours.
Also, mtbf is not an estimate of how long a hard disk will last, just the chances of a fairly new drive going out unexpectedly. Like if they tested new hard disks for 500 hours to weed out the duds, then took 1000 of the survivors and tested them for another 1000 hours, and 4 went dead, they could claim an mtbf of 1000*1000/4=250000 hours AFAIK. But you can be sure most of them won't last that long, that's almost 30 years at full load. Like saying if 4 kids in 1000 die between ages 5 and 15, you can claim humans have an mean time between failure of 10*1000/4=2500 years. The real estimated lifetime of a hard disk may be roughly proportional how long the manufacturer is willing to warranty it for. Hard disks intended for server use tend to be warranteed for much longer.
If you use a desktop, max out the ram to minimize disk use and schedule very regular incremental backups, as full backups will also greatly increase disk use. A desktop server will last the longest if it almost only touches the hard disk to perform necessary writes. And be aware that cheap desktops have a high lemon rate.
If you buy a Dell PowerEdge 400sc, their cheapest line of servers, you're actually getting low end desktop hardware in an easy-access case for the about same price as their similar desktops, plus integrated gigabit. So using a desktop as a server isn't too horrible, if it's not vital.
A good raid 5 file server with scsi drives, plenty of ecc ram, and a reduntant power supply can live almost forever without maintenance. They've been accidentally sealed behind walls without anyone noticing until many years later.
I've seen some of the hardware google uses and it's not fancy name brand redundant everything servers. In fact their setups might shock some IT traditionalists. They seem to use standard mother boards mounted on open shelfs(no case), with a psu and an IDE hard drive.
From what I've read about google their philosophy is it's better to have a number of redundant servers, then one critical server.
we just bought five new 2u Dell Power Edge 2850's for 2k each!. That included two 2.8 Intel Xeons, three 36 gb seagate scsi 10K RPM drives (can have 6 total) with a 256MB RAID controlller , dual power supplies, dual gig ethernet, and no OS installed. Thats the price you just paid for a decent workstation. It's a bad idea.
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.
Besides that, if you don't have a specific vendor that you are required to order from, you can often find rackmount "server" machines for a fraction of the cost of an IBM, HP, or Dell. We use several 1U and 3U servers where I work that we purchased from 8anet. Aside from the cases (check out the chenbro ones, very nice hot-swap features) and power supplies being more expensive, and motherboards having better management features (go with Supermicro, they have very nice network monitoring utilities, for things like fan speed, power, and temps, as well as expansion for hardware-based monitoring) and the fact that you will probably want registered DRAMs, there is no real difference between a server and a common tower workstation. All of those features which add to the price (hot-swap drives, redundant power supplies, high-end motherboards, and registered memory) are features that are really, REALLY, worth it when you are talking about machines that must be available when you need them.
I believe we paid around $4500 for our 3U P4 2.8GHz 2GB RAM 2.4TB SATA RAID-5 NAS machine with N+1 redundant power supplies, about the same for our 3U Dual Xeon 2.8GHz 4GB RAM 52GB (6 15K rpm 18GB drives total) SCSI U320 RAID-10 database machines with N+1 redundant power supplies, and our 1U P4 2.8GHz 2GB RAM 80GB SATA RAID-1 web servers each run around $1400 (no redundant power supplies). Point is, there ARE other options, you don't have to use low-end hardware just because you can't afford IBM. Besides, why pay for servers from IBM, HP, or Dell, when you can buy two of the same caliber machine for the same amount of money or less. With two machines, you can do things like load balancing, increasing performance and adding redundancy at the same time.
--That's the point of being root, you can do anything you want, even if it's stupid.
Oh, yeah, and if you're looking to save money, blades are DEFINITELY not what you want. Blades are not meant to be cheap, they're meant to save space, for when space is worth more than money. Even in that case, though, I would look into the half-depth 1U rackmounts before going to blades, unless you're talking about maintaining a very large number of machines, since they are much cheaper (case and power supply $389 from 8anet, can fit 2 in each unit).
--That's the point of being root, you can do anything you want, even if it's stupid.
You know, you should never post without at least *seeing* both sides of what you're talking about. Your post is uninformed and you will probably see that when you buy and use your first real server.
You are not considering the actual cost of owning and running these machines, only the initial cost of hardware. If you learn how to do a proper analysis of the costs associated with each machine over a 3-5 year period, the typical server lifespan, you will find that purchasing an entry level server will be far less expensive. Better memory (ECC), server chipsets (Intel 7xxx vs Intel 865 for example), and chassis designed to provide adequate airflow for a server is a bargain compared to downtime while you fix your Dimension "server" every couple of months.
You can do a 1U P4 3.0 with mirrored Enterprise quality SATA disks and 1GB of ECC RAM for well under $2000. Take a look at the Intel SR1325TP1-E server platform. It's the server chassis with proper cooling with an Intel TP1 board installed. The board has dual onboard nics and the chassis has about five fans. Very nice, and runs $500. Add the CPU for about $200, memory, and disks (SATA, CD, floppy) and you are done.
I assume USB is to make it removable, but for that to do any good, you need to actually remove it, which means having at least one other USB drive to swap in when the one is off-site. If the budget doesn't allow for that, and you're just going to leave the backup there on top of the server all the time, then save yourself some money and mount an IDE drive in the case, and take advantage of the better speed to get daily backups done more effectively. Alternatively, do on-site daily backups across the network to an old machine otherwise destined for recycling but with a new large hard drive; that'll give you better disaster recovery ability if the main server dies and takes its drives with it.
If you don't need a UPS, make sure you at least have a surge supressor.
Please ignore that comment. You do need a UPS. Skimp on the specs and buy whatever's on sale with rebates at Best Buy this week if you must, but any machine you're going to call a "server" needs at least a few minutes of battery power to protect its data from sudden power outages and its electronics from power slumps.
http://alternatives.rzero.com/
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.
This works great for google because they have a stateless HTTP-based application.
Joe LAN Admin is usually dealing with fileserver and database applications that use long-lasting connections and lots of server state. (Even many HTTP apps make heavy use of server-side sessions.) There simply aren't cheap fail-over solutions for these apps. So it makes a lot more sense to buy a box that can maintain the uptime by itself.
Whenever I hear the word 'Innovation', I reach for my pistol.
I can't speak to other brands of machine, because we only have Dells, but insist on proper monitorability.