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Where are the Large RAM Systems?
CaptCanuk asks: "I've been charged with finding a system with 16 GB of memory and have had a really hard time in acquiring one (especially with a PCIE 16x slot). Linux is at the forefront of these 'large system memory' systems and beyond beta versions of Windows XP, is the only OS that supports the 64 bit memory addressing required to use this much RAM. When I asked large beige box wholesalers, I'd get comments from 'Why do you want a 16GB harddrive...you want MEMORY? are you sure?' to 'No motherboard supports more than 4GB of memory; everyone knows that'. Where are these mythical large memory systems? Do you think such workstation configurations will become pervasive in the future? Will it take Microsoft's Windows XP 64 bit to legitimize their existence in larger quantities?"
... you want a 16 Gig RAM box and you expect to find it "in the offer" of some company ? Do you want to use it as a desktop or a server ? Why DO you need 16G RAM in a desktop ? Why do you expect to find a "server" at normal retailers ?
That being said, what stops you from buying the components YOU know exist that *can* support such a large memory and build the damn PC YOURSELF ?
By reading this signature you agree to not disagree with the post you just read.
Yeah, I know... it is not an answer... and it doesnt really matter... but out of raw curiosity... what are you doing that you need that much memory? Bilz
Or you could just write better software. Really, I gotta wonder, what the hell are you running that requires that many pages to be in memory at the same time. Obviously you need this kind of stuff if you're running a huge database or something, but a desktop machine? You're kiding right?
How we know is more important than what we know.
The Opteron systems I've seen that support > 8GB of RAM do so with registered ECC 2GB DIMMs. Until recently, it wasn't easy to find 2GB DIMMs. The cost is somewhere between $450 to $1200 per DIMM (for DDR333), and you'll need 8 of them. You can find some by Transcend on NewEgg. Crucial carries them at > $800/DIMM.
So even though there have been quite a few Opteron motherboards that have 16GB support on the datasheet, vendors haven't had 2GB DIMMs to fill them out readily.
Has anyone tried a 2GB DIMM in an Apple G5 system?
I think that would be implied by the requirement for a 16x pci express slot. As far as I'm aware, the only cards for these slots are video -- pci express raid & network cards do plenty with only a 1x pci express.
Poster should also keep in mind the heat, noise and power considerations of a box this size
Hell yeah. Monster UPS underneath, to hold up the servers, switches, blah blah in the event of power outage, also the server room lights and the aircon and the security thereof so you can maintain operation or at least gracefully shut down in the event of outage. It has to be in a decent room of its own - you don't want the sound of a jet taking off in the corner of your open-plan office.
And failover? if you're gonna go one-big-box, then you're in the single point of failure area (ooh, we're back to clustering again).
Of course you may just want an impressive box in the corner and not really worry enormously about 24x7 ops. If that's the motivation though, why not just buy an impressive case with a bunch of flashing lights?
Screw you all! I'm off to the pub
Q: Where are these mythical large memory systems?
A: They've existed for years in mainframe and scientific computing circles, just as 64 bit hardware has existed (Alpha chip, SPARCv9, MIPS) for years and OS's capable of dealing with 64 bits have existed for years.
Q: Do you think such workstation configurations will become pervasive in the future?
A: Yes.
Q: Will it take Microsoft's Windows XP 64 bit to legitimize their existence in larger quantities?
A: "Legitimize" is a word I don't like to use in the same sentence as Microsoft. But your intuition is correct. Once Microsoft brings out a reliable 64 bit OS that is backward compatible with its 32 bit offerings, you'll see more popularity and lower prices for systems with more than 4 GB of memory. Let's hope everyone's learned the Bad Way of Doing Things from the 16->32 bit Windows transition a dozen years ago. OTOH, I suspect glitches in the transition will be leveraged to encourage upgrading...
"Provided by the management for your protection."
I can see is in CASE tools. I already was forced up to 2GB of RAM and that won't be enough for very much longer.
If I had to model the Peoplesoft tools, well 4GB won't do that either.
On IA32, the limit exists on Linux as well as Windows. This is a hardware limitation of 32-bit addresses, as you pointed out. However, it's possible to "window" the higher memory into a fixed area under the 4 GB limit, similar to how XMM and EMM worked in the days of MS-DOS and extended memory managers.
As for memory being reserved for kernel space, that's a necessity in order for the kernel to be able to differentiate between user space and kernel space. It would be horrifically inefficient for the kernel to have to scan through a bunch of tables to figure out if a particular pointer is a kernel pointer or a user pointer. Setting an arbitrary boundary between kernel and user space lets the kernel do a simple test -- is this pointer greater than the kernel space limit? If so, it's a kernel pointer.
On Linux the boundary can be set at either 2 GB or 3 GB.
While true today, it won't be for much longer Windows Server 2003 x64 is scheduled for a first half 2005 delivery (next couple months) and the big apps (Exchange and SQL) each have an update coming to support it (2003 SP2 for Exchange and SQL2005 for SQL Server). Linux gets around it by allowing 64bit equipment with 40bit physical addressing to act like what it actually is, 64bit. The kernal and libraries have been updated for a long time and some major apps have been 64bit clean for a long time due to running on other UNIX platforms where 64bit has been standard for some time, and others have been updated since the Opteron was launched and 64bit became cheaper. But you are partly correct that under a standard x86 kernel your processes are limited to 2GB, or 3-3.5GB with optional switches.
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
I just bought a few 16GB Opterons a few months ago (and ordered more last week).
The 2GB DIMMs ran us around $880 each (registered ECC).
You can also get 4GB DIMMs now, but they'll run you about $2500 a pop. (yow!)
The company I'm dealing with (rackable.com) also offers a quad opteron system that has 16 slots, so you can get 16GB with 1GB DIMMs or 64GB with 4GB DIMMs (and 40 grand).
These systems are replacing a Sun V880 that previously provided our large memory support, and run the tools we have much faster.