24gb ram as a substitute for SSD?

[geofelt]

The new X58 motherboards will soon increase ram support 24gb. This will happen when 4gb sticks become available. In ddr2 form, they now cost $100, and the price should drop sometime.
If I spent $600 on 6 sticks to get 24gb of ram, what would be the effect? The $600 is what you could pay for a top end SSD.

I would need to upgrade to vista ultimate(or maybe business) because home premium support stops at 16gb.

Once booted, vista should keep anything it loads in ram for future use. With 24gb, that is lots of stuff. If you play a game regularly, 24gb should hold it in it's entirety.
You would eliminate many many reads.completely. Level loads should be instantaneous. It should be easier to manage than a 24gb SSD, because Vista will be keeping the most frequently used loaded data.
Instead of rebooting, I would use sleep, which keeps things loades, but reduces power on everything. Hibernate might be an option, but writing out 24gb might take longer than rebooting. I don't know about that.

Does anyone with 12gb or more out there have any thoughts on this?

 

[typerazor]

i have read of this, it loads the RAM with the OS and programs and such and when you shut down it writes it to the hdd
i believe its called virtual machine

but seriously, gigabyte made a pci board that did this before ssd came out but it was ddr2 and the board was a rip to begin with (300$)
also it had a battery that had to be charged up so like if you lost power for a week you lost your stuff

 

[mford66215]

Just because there's room to cache everything doesn't mean the system will automatically cache it for you. It's unlikely you'll see the drag accessing a pagefile causes though. If you already had the ram I'd suggest looking into a ramdisk for temp files, etc..., but I wouldn't invest that kind of money on the experiment myself.

IMHO, I think that overall you'd be better off getting the SSD for a boot disk, and having as much ram as you can afford after that.

 

[MRFS]

G.Skill have a 16GB kit with 4 x 4GB DIMMs, but those are DDR2.
We're looking at that kit as a way of reaching 16GB on a P45 chipset
e.g. ASUS P5Q Premium. That memory is in the QVL for the P5Q Premium.


I would recommend that you look into RamDisk Plus from www.superspeed.com :

http://www.superspeed.com/desktop/ramdisk.php

It now addresses unmanaged Windows memory on XP x32 systems.

And, there are versions for 32-bit and 64-bit Vista too, described above.


Here's one system development sequence to consider
(some of which you probably already know):

(1) populate all 6 Core i7 DIMM slots with 4GB modules (24GB total);

(2) install your OS to a very fast hard drive e.g. VelociRaptor or 15,000 rpm SAS drive;

(3) download and install RamDisk Plus version 9;

(4) configure a healthy ramdisk e.g. 16-20GB, leaving 4-8GB for the OS;

(5) assign an unused NFTS drive letter to that ramdisk;

(6) enable the option which saves and restores all ramdisk contents
between shutdowns and startups;

(7) re-boot and test your ramdisk with routine I/O
e.g. XCOPY a large dataset to that drive letter;

(8) install your application(s) to that ramdisk drive letter;

(9) test those applications thoroughly;

(10) if you are ambitious, play around with PAE mode
to see if it makes any difference; this option is enabled
by default when Data Execution Prevention is enabled
on XP 32-bit systems.


If all goes well, you can shutdown your system and
RamDisk Plus will save the entire contents of your ramdisk
to a rotating hard drive e.g. VelociRaptor. It may take a while
but the wait will definitely be worth it!

The Core i7 stock memory bandwidth of 25,000 Megabyte per second (25GB/sec)
will definitely accelerate routine file system I/O with such an advanced setup.


MRFS

 

[geofelt]

Based on the posts so far, I don't think I made my idea very clear.

My objective is to eliminate I/O, not do them faster.

If I were to develop an OS, one of the things I would do for content management would be to leave loaded modules in ram, after they were used. I would keep track of which modules are used most often, and which ones were the least recently referenced. If I needed to load a module from the hard drive, I would first look to see if there was a valid copy already in ram and reuse it. Otherwise, I would load it into the space that was occupied by the least recently used data in ram. This is how an OS does paging, and I would be very surprised if the microsoft developers did not do something like this. ON the assumption that they manage modules in ram well, then the 24gb will always hold the most useful data for the system. If the OS and your current favorite program fit entirely in 24gb, then you would never have to do a read I/O after the initial load.
Some data will naturally have to be written out for updates, but a fast hard drive like the Velociraptor is probably better than a SSD for updates.

There are several problems with ramdisks, and I have tried one in the past:
It worked, but I was not too confident of it's compatibility.
In the past, you would be hard pressed to have one much larger than 4gb.
You had to populate it with folders that you guessed would be useful, but were never sure.
Some modules or programs are highly used and some are not. It would be hard to separate those two out. I want simple maintenance.
A ram disk of 20gb would add about 20 seconds to shutdown times, and startup times. I assume that you have a good hard drive capable of sustaining a 100mb/sec transfer rate.

These 4gb ram modules are not yet available, and perhaps they will be excessively pricey. I am hoping that someone who has installed 12gb or 16gb might be able to offer some comments on the benefits of extra ram.

I am also hoping that there might be a vista developer out there that might give some insight on how vista might be managing ram.

 

[MRFS]

System and application software are all coded
to do READs and WRITEs -- logically speaking.

So, you are never going to "eliminate I/O".

I think you mean to eliminate READs and WRITEs
to and from relatively slow devices and replace them
with READs and WRITEs to and from RAM without
involving relatively slow peripherals devices
like rotating disk drives.

Least Recently Used ("LRU") algorithms have been around
for a long time, particularly in properly implemented
virtual memory systems.


These products might do what you want:

http://www.superspeed.com/desktop/supercache.php

http://www.superspeed.com/desktop/supervolume.php


MRFS

 

[bc4]

The programming is simply not close to that level yet. maybe in 10 years.

Many programs, need I/O to work. They can not simply load into ram and be done. many subroutines can not just manipulate data while loaded into ram. It must be moved, deleted and reloaded.

Think off it as loading your PC with unlimited RAM and then unplugging the hard drive... sure everything that is needed should be in ram but even if you could somehow disable all the warnings... you PC would crash w/o a HD.

So in short, you can not just eliminate the I/O. Your best bet is to try and make them faster.

edit: guess MRFS beat me to it

 

[JDocs]

The only way to truely eliminate I/O is to remove the memory and HDD. Memory is designed for I/O as well.

😛

 

[geofelt]

After doing some more research, it seems that the Vista "superfetch" feature will do exactly what I want. On smaller systems, like 2-4gb, it won't help. On systems with 8gb and over, it looks to be possibly very effective.
Not only does it cache programs and data in the extra space, it tries to anticipate your use of them and load them into the cache in advance of need, using low priority I/O. I am now thinking that 12 or 24gb would hold my typical usage, and never have to be replenished.

My only question now, is 12gb enough, or would 24gb be better? DDR2 is now available in 4gb modules, giving a capability of 16gb on current 775 motherboards. I would be interested in anyone's actual experience with >8gb.

 

[Nik_I]

there is a such thing as a ram disk. it's basically an enclosure with DIMMs in it. the read/write speeds are incredible. but the problem is that it always needs a power source or else the data would be erased.