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Hard Drive of the Future: Ram Drive
benzick writes "3d Retreat has posted a hands on look at a 2gig ram drive called the Rocket Drive. Article blurb: Overall the rocket drive is the best in I/O performance I have seen. It outperforms U160 SCSI drives by almost a factor of two. Yet there are some drawbacks to the Rocket drive, foremost is the price, although listed at the end of the review is some alternative pricing options to make it less expensive. And the rocket drive can not act as a boot drive. Also, if you have some extra money to spend, you can use multiple rocket drives in parallel."
Fundamentally, you're always better just to use caching. Essentially, this amounts to a 2GB dedicated disk cache, except that the power supply ensures that the contents survive boots (though I don't know how it would do in a power failure). Anyway, how often do people reboot their machines nowadays? Stuff stays in my computer's cache for months at a time.
So, why not just add the 2GB to your main RAM? Then the OS could use it as a disk cache if it were so inclined (and you'd be right where you are with a ramdrive) or else the OS could use it as actual RAM if you needed it.
In short, RAM is just like a ramdrive except more flexible.
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
Here's some neat facts. No real solution though. Reply with one if you have it...
Ram = Fast
Cache = faster ram
On Board Cache = faster
1. Processors used to not have a quick way to get to ram so cache was created (faster and expensive ram) and put on a chip.
2. Cache proved to be too expensive so they put it off the chips (pII)'s. Celereon's even took off some of the Cache.
3. Now that ram drives will be created, it's just another link in the chain to the HD.
now it'll be:
HD->Ramdrive->Ram->off chip cache->onboard cache
Each one of those levels cost more as you move to the right. This just puts another link in the chain.
And here's why:
You can put a couple gigs of RAM on your motherboard, where the bandwidth to the CPU is at least 10x the fastest SCSI interface. Run any modern OS on there, and all of that main memory is going to be used a filesystem cache. Voila: all the benefits of a RAM disk (fast seek, throughput) and none of the drawbacks (no need for a separate disk backup).
If what you want is a TRUE ram disk, i.e. not backed by magnetic storage at all, then you can do this in Linux or FreeBSD by setting aside a chunk of main RAM as a file system. I don't know if you can do that in OSX or Windows...
But a RAM disk on the SCSI bus? What's the point?
The trick is not to put something on it that remains constant, but something that changes all the time. So instead of the actual browser, dump the cache on it. Tell your OS and software to use the drive for temporary storage(swapfile for example) and then you'll get the most out of it. Something the article does not specify but which my software driven Ramdrive allows me to do is to actually load a disk image into the drive on bootup, allowing you for example to permanently install an entire piece of software on it permanently which will then only have to be loaded from the harddrive once...
People replying to my sig annoy me. That's why I change it all the time.
Okay, fair enough, I didn't see the bit about it keeping the data on there using an external power supply.. but..
Most Slashdotters are the type who leave their PCs on 24/7 anyway, and run relatively stable operating systems. And if the power cuts out, you're going to lose the RAM drive anyway.
I can see the use of this RAM drive in video setups or on DVD encoding/production desks, but for regular Joe (or even a Slashdot user)? No.
mogorific carpentry experiments
That's an absurd price for what little there is to be gained from this. Clearly the cash would be better spent on a new MB with an extra 2 gig on it - it could be used as a ram disk if you really wanted, or as a cache, or for any number of uses beyond a silly-cone hard drive. Better to be able to deal with the memory as memory than memory pretending to be disk. And for a lot less money.
I'm an American. I love this country and the freedoms that we used to have.
The only justification I can come up with to purchase one of these cards is if you have already maxed out your motherboard system RAM.
Does anyone know if this maps in as a normal ATA or SCSI controller? Or do you need a special windows only driver?
If linux can recognize it as a normal block device, and I was rich enough to already have 4G of PC2700 on my mobo, then a mkswap/swapon on this device would become beneficial.
Also, can you install more then one in a system?
It appears Ockham lost his razor and grew a beard.
To be fair of course, DRAM drives do offer the following features and are used as "caches" in many large server farms (like google, ebay, etc):
1. DRAM drives suffer no penalty to random i/o workloads while disks even in RAID configurations do suffer penalties.
2. DRAM drives export a larger addressable cache area, extending main memory. Throw a couple of these 4 GB modules into your server, and you have essentially extended the cachable address space beyond the 4GB limit of 32-bit CPUs to 16GBs + 4 GB of main memory. For web farm servers this is a nice feature that can be cost effective.
However, in no way should DRAM disks be confused with real drives, where persistence of data is truely important. For example, most RAM drives don't even bother with an external power cable.
Someone you trust is one of us.
HD->Ramdrive->Ram->off chip cache->onboard cache
Each one of those levels cost more as you move to the right. This just puts another link in the chain.
Sure about that? For the price of the Ramdrive, I could easily get 2GB of DDR. Hell, for the price of the Ramdrive I could get a motherboard that supported 64GB and fill a moderate chunk of it. That thing has lower speed and greater access time than main memory and costs more, so just using RAM as disk cache would appear to be more useful under the majority of circumstances.
If these guys had made this compatible with scsi, like emulating a scsi card and 1 device, so it could boot it would rock.
...
From power off to up and runnig in seconds !
This would be ideal to store an OS, even for a server, and have the HDs configured to copy the os back to the card and reboot in case it fails to boot from the card for some reason
Hook the power source to a ups and you can probably keep the info for more than a week without external power should you need. (i mean, how much juice can this need?)
What if you could boot from this drive? If it were Flash Ram then presumably you could store your operating system on a RAM Drive and get it to boot instantly cutting down on the boring and annoying wait for the computer to start up.
Another drive could be used for storing files and such like (if it were thought to be somewhat dangerous medium to *store*) but in anycase it would be lovely to get instantly booting computers.
In addition, rather than booting, couldn't these drives make possible a kind-of ghost-like save boot-up state. ie Copy into memory very quickly the state of the computer just following boot up. Now that would surely speed up the booting process.
And I know everyone might say, oh that doesn't matter, but even though I use a Powerbook which with OS X stays up almost forever - I *still* need to boot occassionally. And it is *painful* to wait for.
Once it is built into my laptop I will be well happy... I hate chugging drives... and silence is golden
---- The Open Source Record Label : : LOCARECORDS.COM
Most people complain about how this drive or RAM disks are completely wiped out by a power loss, but couldnt that also be used as a great security feature. If you have alot of data that you dont want someone (read: The Government) getting their hands on or taking as evidence, just keep it on a drive protected by a UPS, then if you need to wipe it out quickly and completely, just pull the plug. Or if a few lovely FBI agents come and take your computer, they do it for you.
"There's no way to rule innocent men. The only power any government has is the power to crack down on criminals."
Could one use this for swap space? Swap could be regenerated between power off (say when you move the machine). Then you could have a startup script see if this thing was configged on boot up and if it was, use the swap. If not, it could config it as swap and then reboot? Am I off base here? Swaps would be lightening fast and if you happen to lose swap when powered off it ain't no big deal.
Gorkman
n.
:)
Most modern Fighter jets use ramdrives exclusively because the high-G manuvers, shaking, ect would cause a normal drives heads to go smashing into the platters. I know the B2-stealth has some, so does the F-16.
When you're the goverment, and you want reliable killing machines, 250k for a 250meg ram drive back in 1987 isn't even an afterthought. It's a requirement. Now that it's dirt cheap to produce memory, it can finally trickle down in price enough to have become feasable for a civilian to afford one.
I know originally the early drives were used to hold map data for the HUD, which was basically just the data gained from our digital elevation modeling sattelites launched in the 80's. Given the advances in 3d modeling and sattelite map aquisition, I would guess whatever system they're using today probably contains terrabytes of map data.
I'm sure the old green vector graphic huds have been replaced with something a lot better to utilize the new data too. I'd suspect that in the actual control area there must be a LCD display, much like what you see on a modern 737.
It must be one helluva video game for them pilots
I've had the pleasure of playing with RAM based storage devices at work. They're a lot of fun. The particular models we used were external, SCSI, memory based, with a battery backup and internal disk for long-term storage.
The nice thing is that they can drive as many reads/writes as you can get out of the SCSI channel. Seek time isn't a factor at all. We're talking disk performance through the roof here! There are also UltraSCSI and other types that'll go even faster. But the only real limitation is the link between the drive and the computer.
Still, the data rate doesn't approach what this PCI based solution has going. But what I use is a more 'enterprise' solution. You've got internal battery backup and disk backup. If the unit is off the mains, the battery kicks in. After 30 minutes, it stops all IO, dumps to disk, and shuts off. When power is restored, it loads back in from disk.
This PCI solution is way cheaper than the external drives that I've used. Just it doesn't appear to have the reliability... or the commodity standards that'll let it hook up to just about any type of system. Still, quite neat!
Something the article does not specify but which my software driven Ramdrive allows me to do is to actually load a disk image into the drive on bootup
:-)
You wouldn't be so kind as to reply with a link to said software ram drive?
I used this trick on my PowerMac 7100 back in the day, having loaded it up with 136MB ram, an insane amount for 1996... I used to run Marathon off the built-in System 7.5 software ramdisk.
Exactly. And by using it as a 'ram disk' you're giving up the huge advantage that ram has, while not decreasing the cost much. I mean, if this system used 70ns ram, it would be just as fast given bus limitations, but much cheaper... cheaper, that is, if anyone made 70ns ram any more. What it comes down to is that if we want radical ideas like this to be feasible (and this is a radical idea, in the sense that no one thought about it when deciding the current pc architecture), we need a lot more flexibility in how systems are designed. I was recently working on a random number generator in hardware for crypto purposes, and the pci bus simply didn't have enough bandwidth, so we ended up fitting an fpga into a memory slot, the exact opposite of what this ramdisk is doing. What we need is direct access to the memory bus itself through some connector (or better yet, to the hypertransport bus between the cpu and the memory controller), which would allow devices like the ram disk, or simply ram cards like you describe, to work with the current pc architecture. Timing on such a bus would be a bitch, but you could assume it remains unused except for systems with truly special needs.
I've had this sig for three days.
The point is that with the drives that I have used (SCSI-U2W through fibre channel) is that they used good old fashioned interfaces which meant that they were plug compatible with older hardware.
I mean, with this type of technology i believe any geek would feel a **bit** insecure, for if the power supply to those rams goes out, you are doomed. I believe that the only benefits of this type of technology right no are UBER fast seek imes and R/W times. IBM is about 2 years away from producing a fully functional MRAM drive (i believe that they do have sa coulpe of prototypes now that work but their R/W times are absolutley horrendous) that will need no power to store data (once it is written that is). The other alternative would be to have some sort of internal RAID HDD with each platter (or side of the platter) accting as one independent unit, i believe ths may have been tried before, but there have been some problems with synchronisation? (anyone knows more about hat one?)
Live for the present, learn from the past, and dream of the future!
If you're willing to fork out the money, there's several manufacturers who have been puttng out genuine static ram drives for a while. They have microsecond access times, sizes up to 80-ish GB last I saw, IDE and SCSI interfaces, and can have sustained bandwidths limited only by the bus speed. They also consume less power, generate less heat, and don't fail as often because there's no moving parts. They solved the limited write cycle problem by having the drive logic remap blocks of data to spread the write wear around the drive.
FOr a bleeding edge example, check out E-DISK's soon-to-be-available Ultra320 drive (they're released other similar drives before, just not at this performance level):
Size: up to 155GB
Access time: 33-48 us (microsecond)
IOPS: 9500 - 50000 per second
Burst data rate: 320 MBps
Sustained data rate: 230 MBps
Full Erase (Security feature, press a button): around 26 seconds.
ECC error correction, MTBF around 2 million hours, 10 year data integrity.
Write life-cycle of in excess of 100 years at 100 GB of writes per day.
11*43+456^2
At Comdex, a long time ago (maybe as much as 10 years), I stopped by a booth that had this wonderful new technology - an external hard drive which was made entirely of RAM! Current hard drive quantities of RAM(don't remember the exact capacity, but it was significant.) And it was only $15,000 (comparable drive space at the time was one tenth the price.) Wow! (Ok, sarcasm off)
:)
I asked that man what would happen if the power was lost. He said that the box had a battery and a hard drive of the RAM capacity inside. If the power was lost, the battery would power it long enough to write all the data to the hard drive. I asked what the advantage was over a regular hard drive. He said access speed and no moving parts. Ok, great benefit, but it didn't seem the value was there for 10x the cost of a drive itself. Anyone remember this?
I started waiting years ago for someone to come up with a board where I could plug in all those 256k, 30 pin SIMMs that we took out of the Mac Plus' when we upgraded them to 4 MB of memory so I could use them for storage. Never happened (that I know). Now I'm waiting for the same thing for this ever mounting stack of 4, 8, 16 and even 32MB, 72 pin SIMMs.
Where is the real innovation? I mean, our favored OS here can run well on all this old hardware - 486 and the like, but where are the little trinkets for us cheap SOB's like me? I just want a 5 1/4 external case with a 25 pin D connector that will connect to my SCSI card. The board inside should have jillions of 72 pin SIMM sockets (in pairs is ok, multi-level board is ok) and a connector for an old ATAPI 2 or 3 Gig laptop drive. The case should have room for a little battery to do what that really expensive drive could do years ago to backup in case of a power failure. Hell, I'd even pay 50 bucks or so for it. Any takers?
I'm not an EE so I'm not up to making it myself, but someone out there would consider it a fun project...
You know, reuse, recycle, make the world a better place. I don't want to have to throw out all this memory or sell it for a quarter a stick. I guess I could use the dremel tool, drill little holes in them and make geek earrings, but I don't wanna have to do that either.
If anyone has any ideas, lemme know.
BTW, no need to call me a cheap SOB luddite, I already did that...
War is Peace. Freedom is Slavery. Ignorance is Strength. - George Orwell or George Bush?
Performance gains of "almost a factor of two?"
Does anyone else read that as an endorsement of the usefulness of buffering and other performance technologies applied to disk drives?
I'd imagine that applications in ruggedized systems or devices that need to be exposed to significant acceleration or zero gravity will be more important than the speed increases, but, I'm quite surprised that a 15krpm SCSI drive comes this close to a RAM device.
One other benchmark that would be useful, would be to compare the speed to the normal RAM in a given system. Is it a net gain to have your RAM on an expansion card? Or would a RAM drive on the regular memory space be better? Is this more or less expensive than system RAM?
-fb Everything not expressly forbidden is now mandatory.
That's interesting. I didn't know this. Does this mean that format option in the BIOS is no longer a low-level format?
Actually, yes. It's some sort of funky medium-level format, IIRC (and it may even screw up your IDE drives permanently). But then again, the true low-level format includes all sorts of special blocks that store tracking information and bad sector tables. You wouldn't want your BIOS to screw with that. I don't trust my BIOS farther than I can throw it! (And, btw, a 120G drive actually has 130G-150G of disk space... you just can't use it ;)
--TheOrangeSquid Is it any wonder things seem so awry? We swim in a sea of confusion and don't have to think to survive
So... would this mean there's no real way to do a secure wipe of files on modern drives? Pardon me if I sound ignorant on this subject, because I am frankly...
You're, of course, correct. *sigh* I just guess I haven't progressed much in my understanding of disk drives from the old 8-bit days when your BIOS was exactly the thing that was supposed to handle all that low-level stuff.
The Rocket Drive itself looks wonderfully impressive... thought the price may be a bit extreme. I noted two things from this article, however:
:)
1)The Rocket Drive only attaches through a regular 32-bit/33mhz PCI slot. You would expect at least a 64-bit/33mhz card... if not faster than that. The drive itself may not be able to transfer faster than 100 MB/s, but you must also consider the other devices attached through that PCI bus. This device can easily hog nearly all the bandwidth available. Not exactly an ideal situation.
2)The drive that is compared against the Rocket Drive is claimed to be a Ultra160 15,000rpm drive. This would not be a bad choice for comparison, since it is the fastest single type of drive available... and the Rocket Drives direct competition. However, how many 15,000rpm drives have you seen that average out with a 13.1ms latency, and cannot achieve an average throughput higher than 38 Mb/s? None that I know of. I happen to own a 36gig U160 10,000rpm Cheatah. My Cheatah, using the same synthetic benchmarks, can pull under 6 ms latency with an average throughput of 49 Mb/s.
No, I'm not trying to tout my drive's speed. I'm simply pointing out that the implementation of this device is a little strange for a device designed for extreme workstations and mid-range servers. And that the benchmark numbers of the comparison drive are at best waaaay skewed. They simply cannot be correct. A 15k rpm drive IS MUCH FASTER THAN THAT!
That being said... who wouldn't like a 4 gig ram-drive?!
/dev/random