Where are the Large RAM Systems? 185
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?"
I'm a bit confused... (Score:1, Interesting)
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 ?
I gotta ask (Score:2, Interesting)
Re:It will take time (Score:3, Interesting)
Re:I gotta ask (Score:3, Interesting)
Spec sheet vs. reality (Score:3, Interesting)
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?
Re:It will take time (Score:2, Interesting)
Re:Open your eyes... (Score:3, Interesting)
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?
Answers (Score:4, Interesting)
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...
One use (Score:3, Interesting)
If I had to model the Peoplesoft tools, well 4GB won't do that either.
Re:Windows 4GB process limit (Score:3, Interesting)
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.
Re:Windows 4GB process limit (Score:3, Interesting)
Spec sheet vs. reality (Score:3, Interesting)
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.