The Ramdisk -- more than a joke?

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Stuh505

Limp Gawd
Joined
Feb 15, 2004
Messages
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It seems more and more people are shifting to the model of installing OS and apps on a small fast drive, possibly with raid0, and then storing their data on some large cheap drives.

There are several good options for this, namely VelociRaptor and SSD. Lots of posts about these already. But they are expensive. Reliable SSD's are not cheap, and the technology is changing fast so it's not an attractive time to invest if you don't have tons of extra cash.

But RAM on the other hand is pretty cheap...for about $400 you can buy 24 GB of DDR3. Then I thought about this RamDisk software. It allows you to mount a portion of RAM as a virtual hard drive. You can opt to have this saved back to a physical disk before powering down. This is enough space to install an operating system on. Granted, you won't be able to claim ultra fast Boot speeds, but who turns off their computer anymore these days anyway?

I'm starting to think this might actually be a practical option for home use...with better performance and much lower cost than even the best SSD. The only complication seems to be in making things integrate well. For example, I could install my main OS on a physical drive, then load up the ram disk, then use VMware to run a 2nd OS off of the ram disk. This is a bit tedious though, and would result in some loss in performance by running in a VM, and also from the unused OS in the background.

I'm wondering if it might be possible to reconfigure the boot cycle so that I can bypass the "primary" OS -- basically, I would need a boot script that simply mounts the ram disk, then looks on that for the OS. When the OS powers down, it would also need to automatically save the state as an image to disk.

Any ideas? Is this feasible?
 
When I researched RAMDISK software a couple of months ago, none of them that I found allowed you to boot from the ramdisk.

I just did a quick search for an add in RAMDISK card and the only 1 I could find was called the Iram from Gigabyte. It is a PCI card, but it can only hold 4 gig of ram. Battery backup is only good for 12 hours also.

Looks like SSD is still the only viable alternative for a boot drive. You would think a memory manufacturer would be all over developing something like this to increase demand for memory modules.

Don
 
You won't find any software that will allow you to "boot" the host computer from the RAMdisk because the RAM contents get wiped in a cold/warm boot cycle, that is simply something you cannot get around due to architecture restrictions. It fucking sucks, and always has, because I was soft-booting from a RAMdisk in an Amiga 500 back in 1984... and there's never been another machine that could do it since. Go figure.

If you really wanted to get 24GB of RAM in a box and do something like that, here's the solution:

- Get the 24GB of RAM and slap it in the machine or build the box.

- Install a 64 bit OS.

- Install a RAMdisk (at the moment this only applies to pre-Windows 7 boxes as I haven't found a decent or seriously reliable RAMdisk just yet for it, still waiting on SuperSpeed.com to update RamDisk Plus for Windows 7) and give it 20GB.

- Install VirtualBox 64 bit (or VMWare if you must, I personally can't stand how big and bloated it is compared to VirtualBox - that's my personal opinion).

- Create a guest VM for the OS you want to run. Here's the kicker to this: you'll be creating a 12-16GB virtual hard drive that sits on the RAMdisk. Once that's created, finish out the VM and give it 2GB of RAM, or 4GB if you're adventurous.

- Install the guest OS into the guest VM you created, and it'll be entirely in RAM - the OS itself as well as the virtual hard drive it's installed upon.

- Use the new pure-RAM powered OS for whatever you want. Of course pure 3D functionality won't work as expected, and you can map out the physical drives as shared folders so they're accessed as easily as a host OS can do it.

From that point on, you're literally using a RAM-powered operating system and it'll be faster than anything else you can imagine. :)

I've done this many times, just not with so much RAM. In 8GB I can set aside 6GB for the RAMdisk, then set up a 4GB virtual hard drive for XP Pro x86 or even XP Pro x64 and still be able to let it use 1-2GB of RAM without issues.

An OS running from RAM... fun stuff, indeed. ;)
 
i researched something similar a while ago as well.

I'm sure it's possible, but it sounds tedious.
interesting thread
http://www.911cd.net/forums//index.php?showtopic=19056

a lot the articles i get focus on windows pe and xpe (i've honestly never played around with either, so i don't know if they can be setup on standard computers to act exactly like normal xp.)
http://technet.microsoft.com/en-us/magazine/2006.10.windowspe.aspx

proof that it's possible: (although through pxe booting...)
http://blog.wired.com/gadgets/2007/07/extreme-world-o.html
 
Stuh505 said:
Reliable SSD's are not cheap, and the technology is changing fast so it's not an attractive time to invest if you don't have tons of extra cash.
Click to expand...
Reliable SSDs simply don't exist, as far as I can tell.

Stuh505 said:
But RAM on the other hand is pretty cheap...for about $400 you can buy 24 GB of DDR3.
Click to expand...
What motherboard supports 12 sticks of DDR3?

Stuh505 said:
Then I thought about this RamDisk software. It allows you to mount a portion of RAM as a virtual hard drive. You can opt to have this saved back to a physical disk before powering down.
Click to expand...
RAM drives can provide good performance in specific applications, but in general use I think you'd be better off leaving the memory for the OS to use for prefetch and file cache.
 
It's not actually necessary to boot from the ram disk. It doesn't matter what you boot from as long as you don't have to load a fully featured OS just to run the real OS in a virtual machine. VM's just have too many limitations to be practical for general use. What is needed is a modified bootstrap loader that can mount the ramdisk image. There's no fundamental reason why this couldn't be done by a company like SuperSpeed. I was looking over their product line and perhaps the best current solution is to use SuperVolume.
 
12GB of DDR3 is the only viable option now.
4GB DDR3 ram sticks that would allow you to go for 24GB cost 400$ a piece and for that price you should just go for Fusion IO and be done with it.
Seems like Ram disks are always one step behind being a viable option for the home enthusiast...
Maybe Dual Socket i7 mobos will have more slots... but that's a whole other type of system

I've setup 8GB ram Disk on my i7 and left 4GB for 64bit OS.
It is fast takes about 1sec to make a duplicate of an CD iso. But I've got jet to install something that would make it useful.

What does SuperVolume allow in regard to RamDisk?
 
@Joe and Don

Maybe im nuts, but this sounds like something that could be pulled off.

Ok with an XP disc when you load the reapair options it has them loaded in a small ramdisk.

Why could we not use "X"partition PE, and boot to that. On a standard HDD.
It then creates us a xGB Ramdisk.
Windows Installation gets copied from "Y" Partition on standard harddrive.
 
It won't work, and believe me, I've been trying for well over a decade to get a working Windows installation on a RAMdisk that you could boot from. Hundreds if not thousands of attempts, configurations, etc. - and WinPE is simply not a tenable solution since it's not a full blown version of XP and nothing anyone can do will change that. :)

If I had the knowledge, and the ability, I would have designed a true bootable RAMdisk device a long, long time ago. The Fusion IO "looks" good on paper but in reality I just don't think it'll do what it claims, and with all the problems it's still having and the fact that it's still not out yet, bleh... I wouldn't even want to use one for review purposes if they sent one my way... ;)
 
Fusion IO isn't viable; it has all the same problems that other FLASH systems have.
 
What does SuperVolume allow in regard to RamDisk?
Click to expand...

If nobody has written a boot loader to allow us to boot a primary OS that resides in a ramdisk image, then it seems SuperVolume offers the next best thing by allowing you to mirror the OS partition into RAM after booting up into your regular OS. After mirroring the partition into RAM, all reads are done in RAM, and all writes are buffered through ram.

It seems that this would have all the same benefits of running your OS purely on a RAm disk, except that booting up isn't faster. There's also some additional benefits, for example if you wanted you could load a different volume into Ram that perhaps wouldn't be able to fit in Ram when your OS was loaded. For example, lets say most of the time you want your OS to be loaded in ram, except sometimes you want to run a game that takes 8 GB of space...you could unmount the OS, re-mount the game which was stored in a RamDisk, and then play the game entirely in RAM.
 
Stuh505 said:
If nobody has written a boot loader to allow us to boot a primary OS that resides in a ramdisk image, then it seems SuperVolume offers the next best thing by allowing you to mirror the OS partition into RAM after booting up into your regular OS. After mirroring the partition into RAM, all reads are done in RAM, and all writes are buffered through ram.

It seems that this would have all the same benefits of running your OS purely on a RAM disk, except that booting up isn't faster. There's also some additional benefits, for example if you wanted you could load a different volume into Ram that perhaps wouldn't be able to fit in Ram when your OS was loaded. For example, lets say most of the time you want your OS to be loaded in ram, except sometimes you want to run a game that takes 8 GB of space...you could unmount the OS, re-mount the game which was stored in a RamDisk, and then play the game entirely in RAM.
Click to expand...

Hmm that sounds pretty interesting.
How does it tell the hdd OS to switch to use its clone on Ram disk?? Sounds rather unusual. Looks like you wouldhave to boot for the second time, like VM, no?
 
Yea but SuperVolume only works on XP, which sucks cause I like Vista/7 better.
 
When I went to 8GB I setup a 6GB ramdisk and loaded a not-quite complete copy of supreme commander in it. I then proceeded to get pissed that it didnt seem to load any faster. :( Maybe if it was installed to the ramdisk, maybe it loaded from the HDD, despite loading the .exe directly. :shrug: You could try that with 12GB, but not enough space for OS needs +install of supcom in 8GB.

My dream machine includes a 4 way R0 of SSDs plus a 16GB ramdisk. Each game gets installed to the ramdisk and then archived to the R0. Want to play? Wipe the ram and transfer to the ramdisk at 1GB/s for loading levels and textures with. Would only need some basic scripts for the file copy operations. Emphasis on on dream machine, there.
 
GLSauron,
That is odd that you didn't notice a speed improvement when playing the game on HD vs. Ramdisk. Maybe that game didn't use enough textures and 3d models for disk access to be a bottleneck. As soon as my motherboard arrives, I'll be doing some tests...and if all goes well, I think I'll be doing the same thing as you suggested...installing each game into a separate ramdisk archive that I mount before playing.

nitrobass, I was wondering about that because it didn't specifically list Vista/7...oh well, they will probably come out with a new version sometime
 
mikeblas said:
Reliable SSDs simply don't exist, as far as I can tell.
Click to expand...
what are you talking about? I haven't seen any issues with SSDs being unreliable, only some problems with stuttering on the ones that use J Micron controllers and some reports of diminished write performance over time, which isn't a big deal since they still smoke any HDD
weren't you spewing this crap in another thread? or was that someone else?
 
Joe Average said:
If I had the knowledge, and the ability, I would have designed a true bootable RAMdisk device a long, long time ago.
Click to expand...
that's a big if :)
how about you just concentrate on putting together a ramdisk guide?
 
All things considered (this is [H] after all), 16g DDR2/800 is not that expensive (~ $450-500 shipped). Using Vista that gives you 12-14g of space to play with on a RAMDisk.

Getting Windows to boot to a RAMDisk will be (more or less) impossible without Redmond's help and consent.

You can (in theory) setup Linux to boot into a RAMDisk. It would involve setting up a read-only bootstrap that brought everything up enough to build the ramdisk filesystem and copy the file structure to it. Your boot times would suck, a lot, but you could do it. I believe that this is how some of the USB flash based Live "CDs" work.
 
I don't really care about boot time as I never turn my computer off.
Boot times suck anyways if you have a raid controller or other hardware that needs to be initialized
 
I have a file server but I like raid on my workstation.
Shortstroked multiboot
Fast sequential for my bluray ripping and remuxing
Doing that on a single disc would blow ass
 
drgnfang said:
You can (in theory) setup Linux to boot into a RAMDisk. It would involve setting up a read-only bootstrap that brought everything up enough to build the ramdisk filesystem and copy the file structure to it. Your boot times would suck, a lot, but you could do it. I believe that this is how some of the USB flash based Live "CDs" work.
Click to expand...
not theory, you can. Yes, a lot of the live cd's give you that option straight off. I have a knoppix cd lying around somewhere, and you can boot it to ramdisk. It takes a while, but boy is the OS snappy once you get it loaded. Plus you can take the cd out at that point.
 
The theory comes in when you actually setup a working OS that can write back to the disk at periodic intervals. It's not so much whether can or can't do it (you can), but there isn't any out of the box solutions for this that I am aware of. Everything I've seen is custom written by whoever is using it.
 
drgnfang said:
The theory comes in when you actually setup a working OS that can write back to the disk at periodic intervals. It's not so much whether can or can't do it (you can), but there isn't any out of the box solutions for this that I am aware of. Everything I've seen is custom written by whoever is using it.
Click to expand...
true that.... double true.
 
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