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Why Not Solid State Hard Drives?
waterlogged asks: "I was just wondering if anybody has heard of a cheap ram based network drive? Seems to me with the ram prices being at about US. $12.00 for 128 megs that someone hasn't developed a battery backup version of this to plug into a network or even a bus. A gig worth of 8ns seek time storage for $120 anyone? That would just about eliminate any wait in loading programs."
BigSlowTarget asks: "There are some previous articles on Slashdot about vendors selling solid state drives, but they all seem to be quite expensive - particularly given the slide in the cost of memory. Has anyone hacked together a solid state drive to take advantage of $60/GB memory prices? I'd really like to be able to boot and run at solid state speed without spending thousands."
Jah-Wren Ryel asks: "In case you haven't noticed, RAM is incredibly cheap, you can put a gigabyte of PC133 RAM into your machine for less than $60. A year ago, that would have cost more like $600. So now it is feasible for one to have a 10-15GB RAM disk, except for one thing - most motherboards won't support more than 2GB total (4 dimm slots x 512MB per dimm). It seems like it wouldn't be too hard to design a PCI card to hold 20-30 dimms and make that available through a hardware windowing scheme (like EMS/EMM back in the old 16-bit days). With the right drivers it could be used as a big RAM disk or for buffercache. Is there such a product out there? The closest I have seen are solid-state disks that sit on the other end of a scsi bus, are too expensive, and aren't anywhere near as fast as a PCI implementation could be."
So what technical details (and the issues of volatile data and price) may be preventing the construction of RAM based drives, and is there anything else that may be preventing some entrepreneurial soul from bringing such a thing to market?
RAM drives are a great idea, the problem is the IDE or SCSI bus. Seek times and retriveal times can be greatly reduced, but the total bandwidth is still a limitation.
Seagate had developed years ago a standard called IPI, I think. It was for the 30 and 40 megabyte RAM drives that had developed. I know it never took off, but it was specificlly for static RAM drives.
What would be really cool, would be RAM storage with an Infiniband interface. Its possible to use it for storage or for regular memory.
We had a Megastore (core memory!) on a PDP11/45 (which was used as the swapping drive, hence upping the category to 11/50, IIRC) back in the 70's. My Nikon Coolpix uses flashram as a formatted dist, something I'm certain other's have noticed. Flashram is able to store and retain with the power off, but doesn't appear to transfer very fast. Using SDRAM would be fast, but only so long as: A) you have a constant source of current B) you don't test/clear on rebooting the CPU. Certainly old ideas, but as long as you can set up a big ramdisk in your OS and put your large temp/workfiles there, do it.
A feeling of having made the same mistake before: Deja Foobar
Can't comment for other OS, but Linux tends to be pretty good at using all the RAM you've got to cache disk data. Even though I rarely use more than 256 MB, upgrading to 768 MB made a significant performance improvement for me, as Linux quickly fill the remaining 512 MB with disk cache, without me bothering with setting up a ramdrive.
Opus: the Swiss army knife of audio codec
The problem of how to maintain power to all that RAM indefinately is still pretty tricky, but how about this idea. Why not put enough SDRAM on your hard drive to buffer the whole thing? Whenever you read anything off the platters, hold it in RAM, and whenever anything is written, page it back to disk as usual. Thus as you use your system, the speed will continue to improve (up to a point) without tying up system RAM.
I think that you might need a RAID (or RAIM- M == memory :) for RAM in case one of those dimms decides to die on you. Buggered up platters can be rescued in some cases, but if RAM dies, there's no recovery.
/*drunk.. fix later*/
It shouldn't be that hard to rig up a UPS and a drive dump to store the data during periods of non use. So if you have 20Gb of solid state data, just have a set up that would back that up when it's not in use... so you still get the speed of the RAM but also have the reliability as well.
The net interprets censorship as damage and routes around it. -- John Gilmore
i have been very pleased with my sandisk flashdrives. basically they are IDE-interface drives with flash memory instead of spinning platters. 0 ms seek time is nice, so is -silent- and -very very low power- storage. not to mention if you don't have to treat it like an egg.
i've used both the flashdrive from sandisk, and the IDE flash drives from simpletech.
the sandisk flashdrives have sizes from very small (4 MB) to big enough for your MP3s (2 GB). of course they get expensive at the high end :) best things about them are (1) can get them semi-cheap from ebay and (2) standard IDE interface.
-samThe REAL sam_at_caveman_dot_org is user ID 13833.
How about a standard Lithium Polymer rechargable battery? The battery would never need to be replaced, could be outfitted onto the solid state drives with little or no problems and could offer battery backup when the system is off or during a power outage.
Computers could also be designed to bypass the hard drives when the system power is off. I doubt a hard drive would utilize much energy.
Actually, there are a number of ways to ensure that the data is non-volatile. Flash or battery backed RAM come to mind. Bitmicro (www.bitmicro.com) is a vendor that currently sells non-volatile flash based drives. I checked them out a little while ago, but found that it was a bit too pricey for me still.
I'd suggest getting a smallish (1gb or so) flash drive for your windows/linux/amiga/whatever partition, and use some monstrous drive to store all your media files.
These are an example (they even have Linux drivers), but an 8GB unit is still over $20k (see CDW). It's going to be a while until this is affordable (2 orders of magnitude price reduction).
Can You Say Linux? I Knew That You Could.
Why would you bother with one of these?
According to their website, sustained data transfer rate is 80-100MB/s (umm, WHY would it vary if it's all solid state?). Add to the fact that the PCI bus is limited at 133MB/s and there's more than just 1 device using the PCI bus (and a lot of them aren't conservative when it comes to bus usage)...
Or, for 1/4 the price you can pack together 2x75GB drives in a raid 0 array, get 30x as much space AND get the same bandwidth.
No, right now there's not much point to solid state drives. Iff (sorry, math hangover, If and Only If) hard drive prices were to stay the same, and memory prices were to fall by an order of magnitude (lets say 10x) THEN I could see there being a market for this. But you'd also need to use either PCI-64 (533MB/s+) or get some other designed bus to support the much higher throughputs.
But then again this just begs the question, what do you need that much more speed for?
To take advantage of RAMdisks, you pretty much need to have your computer on all the time, or in standby mode when you're not using it. At this point, what do you need much higher disk bandwidth for?
Loading your mp3s or movies?
Loading office in 2s instead of 6s?
running your games (oh wait, that's CPU/GPU intensive not HD).
Quite frankly I don't see the technology or the market right now to create solid state HDs.
If God gave us curiosity
I seem to remember that there was a company working on the idea about 2 years ago of using the rewritable film of a CD-RW as memory.
- - - If the sun is a star, why can't I see it at night?
There is a company in Sweden developing technology that might make both RAM and HDD's obsolete.
:-):
6 01 2
:-)
;)
The swedish R&D site:
http://www.thinfilm.se/
The norwegian mothercompany:
http://www.opticomasa.com/
Article about it (in Swedish however
http://www.nyteknik.se/pub/pub26_3.asp?art_id=1
More material can be found by searching for Opticom, Plastic memory,thinfilm etc..
Interfaces should not be a big bootleneck. Whatever technology used to create the RAM disc. ATA-100 (100MB/s) and SCSI U160 (320MB/s) should be significant. U320 and U640 will come within years.
If the current number of RAM sockets are a limit.. one can always network some MB's stuffed with RAM.
pbRemove(a)ludd.NospamherEluth.RemovEthisse
Anyone in need of computer consulting with unix or programming btw?
You see solid-state disk drives used mainly in relational database management systems as a 'scratch pad' for highly-volatile data.
:D
In order to explain I'll have to do a quick primer on RDBMS' and how they handle memory management.
As you're probably aware, there are a multitude of different operations you can perform on a RDBMS; UPDATE, DELETE, SELECT, etc.
For more efficient queries the RDBMS will cache physical data structures in memory. It may cache parts of the index or recently accessed data. If the cache is full it will kick out the oldest, least used parts to make some room for the new stuff.
To make a long story short, most servers have way more disk space than RAM. As such, it will use a designated 'temp' or scratch area for some of those sorts (and temporary tables) if there are more important things in RAM or it cannot all fit. In Sybase / MS SQL you create a special database for this called 'tempDB'. I'm sure DB2 / Oracle have similar data structures.
Here is where solid-state disks enter the picture. You can buy a small solid-state disk (9GB or less) for cheap. You then 'create' tempDB on the solid state device. That way you can completely eliminate the relatively slow disk drive for things like sorting, temp tables, etc. and devote all of your RAM to caching database information.
To me, this seems a lot better than using solid-state devices exclusively as a storage medium. Initially when you start up your RDBMS the cache is clean. After people run a couple queries the important (and most hit) indexes and data are cached any way so you do not have to worry about touching the disk unless you perform a write. However in most OLTP (online transaction processing; a la web app) it's mostly selects so you wouldn't receive the benefit of the solid-state device unless it wasn't in the cache.
Most SSDD have a battery-backup in them in case of power failure and are generally mated to a corresponding hard drive. When the SSDD is idle it will flush the writes to the HD to keep the HD up-to-date. On a power failure it will immediately dump changed data to the HD (also battery-powered).
For 'home' systems I can't imagine anyone using SSDD as their primary storage. It doesn't make sense - rarely does anyone perform anything that 'demanding' as to require solid-state drives. Plus, if you have a single memory error you would lose the entire thing (break one of your DIMMs and tell me what happens when you try and boot.)
Thanks,
--
Matt
With this trend to continue, OSs should be redesigned. The hard disk has the advantage of keeping the data with no power, but the ram has speed. New pcs could have 3GB of ram and a 40GB ide HD for storage. When the pc boots it would copy the data into its ram and then execute all programs from ram, sure this would take a long boot but with new os to be stable this should not be a problem.
We would have to do some serius os and user interface redesign. If the pc is used for video editing the samples could be kept in memory this would speed thing up a bit, but you would have to save the data to the HD eventualy.
Another great application for this would be chase servers, imagin a organization that does video editing and all the clients have gigabit ethernet, implement servers that have 1TB of ram before the data storage server at night they could sync the data.
Seriusly, we have to think about this, our current view on pc is that ram is way more that hd storage. Diskless clients could make a come back...
hmm... for fun I enjoy launching DDoS attacks against 127.87.42.5
As such, they are fairly old technology, and most of the problems have been ironed out. The problem with power can be solved in a number of ways, for example. You can have battery-backed RAM, or you can have the "RAM" non-volatile by using a design that does not decay rapidly with time. (Flash RAM works this way.)
Another problem has been the capacity of a solid-state hard-drive. This, as has been mentioned, has largely been overcome. I =STILL= believe that wafer-scale chips are the way to go, for this, though. You should be able to make wafers that are tens of terrabytes in capacity, by now.
(The problem with making wafers has always been the purity and the defect levels. Purity just requires you to use something better than skimming. Double distillation, or atomic mass seperation, would give you near 100% purity. You then just cool the resultant in a vaccuum flask, so that the defect rate is negligable.)
Getting back to the modern day, though - how to turn cheap RAM into quality solidisk. This involves making a card, with a whole load of RAM on it. Since you're using conventional RAM, you can't rely on modern-day core memory. This means the fall-back of using battery-backed RAM.
You want TWO batteries, for this. One will be in discharge/recharge mode, the other will be in operational mode. When the batteries switch over, you want the recharged one to be switched first, so that the batteries are in parallel, BEFORE switching over the other. That way, there's no loss of power.
When switching to discharge/recharge mode, the battery must be fully drained, to prevent "memory", where a rechargable battery fails to recharge correctly from a semi-charged state. Once drained, you recharge it to capacity.
The switch-over should happen on one of two events:
This guarantees that you have 175% - 200% of any one battery's lifetime, which should be ample for most purposes. The recharger should tap off the bus' power supply, with the batteries directly powering the RAM at all times. This avoids any problems of messy spikes somehow getting into the computer.
If you want "extra-long-life" SSD technology, you are probably best off using very low-power RAM for the main disk, and using higher-power fast RAM for the cache. The lower the power of the main disk, the better. Static RAM is worth a glance, for this - I think it's usually more efficient than dynamic.
Of course, the =ULTIMATE= solution is to go back to using core memory. (For those who never went to computer science classes, "core memory" is one of the earliest non-volatile digital storage systems. It was a form of magnetic storage, and used semi-permanent magnets to retain the data. Data could only be read by destroying the copy in storage, which mean that a read cycle also had a write cycle. It was slow, but when you had RAM that was guaranteed to retain data for over a century, who cared?)
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
You point is correct but the parent's point is correct as well. We may have 40GB drives, but we are only using a small amount at any given time. Using the strengths of RAM with the strengths of HD's we could see some really interesting hardware. It seems like the middle road (similar to what another poster mentioned) is to substancially boost the amount of RAM used as a disk cache. Add some pseudo-AI drivers and you end up with a situation like this.
User starts Word. As the application is loading and initializing and as the user is working, the hard drive is automatically loading all dictionaries, the other Office programs, the equation editor, the charting program, the clip art, the help files, all .docs you've ever edited, all .txt files, local .html files into your 2 GB RAM buffer on the hard drive. You may never, ever use Word to edit html files, but since RAM is so cheap it doesn't matter.
A complete directory of all files is also stored in the drive's RAM buffer. Searches become instananeous.
As you save files, the saved files are mirrored back to the platter to ensure against power failures, but they are also saved in RAM (with a battery backup) to ensure against head crashes.
Now that the hard drive has memory to burn (so to speak) it stops being a mere storage device and becomes a "autonomous storage unit" that has it's own CPU to assist the computer in it's search for information. Seagate, Maxtor, and all the other drive manufacturers who are about to declare banckrupcy start marketing "ASU : Storage for the 22nd Century" in partnership with the struggling memory companies (who would love to have another market for the slower / cheaper memory technologies).
The technology companies are saved thanks to my idea (until, of course, we find out that Rambus actually owns the patent on ASU's and they start sueing everyone ;-)
Waltz, nymph, for quick jigs vex Bud.
This is exactly what AGP was designed for -- high-bandwidth I/O to main memory, without blocking the PCI bus. Plus, the AGP GART can do most of the address translation you would need. All modern PC (and even Apple) chipsets have an AGP interface, which is wasted on a headless server. . . until now. AGP even provdes extra power (even the obscene AGP PRO), so that an onboard battery/HDD could be used to backup.
> To take advantage of RAMdisks, you pretty much need to have your computer on all the time, or in standby mode when you're not using it.
This is true. *or* you could have your computer net-boot from a a server with one of these. Even 100megabit transferring from memory will feel faster than a local hard disk. And gigabit over copper is becoming very affordabl these days.
A solid-state disk drive with, essentially, zero *seek* time makes this not just a more pleasant experience, but possible. (Okay, so that's an overstatement, we hadn't planned on using SS drives, but the idea does warrant examination!) Remember, there's data transfer rate as well as seek times to worry about, and, to the best of my knowledge, disk drives currently for sale do not max out the available transfer bandwidth. So, with a SS drive, we'd win on seek time and transfer rate, despite the various bus limitations.
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
--
:)), one machine could replace them 10 with only that little step up. Thing is I can't afford 10 machines and the drive subsystem, nor current SSD solutions.
To take advantage of RAMdisks, you pretty much need to have your computer on all the time, or in standby mode when you're not using it. At this point, what do you need much higher disk bandwidth for?
Loading your mp3s or movies?
Loading office in 2s instead of 6s?
running your games (oh wait, that's CPU/GPU intensive not HD).
--
FORGET ABOUT HOME USE, think a bit.
There are limiting factors with hard drives, mainly LATENCY issues, this might not be a problem for you or any home users, but for some specific scenarios, it is, and a BIG one. I give you a specific case where I could benefit from such a system:
Without going in too much details, I work with a lot of files, my workstation generates over 200,000+ files for a single simulation, no it can't be put in a database for now, it has to be accessed from different software with no database support, every other part of the software is optimised to know exactly which file to open, using the maximum of memory, cropping useless data, etc etc... everything is maximized to a more than good level. The only bottleneck I have in my system right now is the drive's latency issue, and beleive me, if I could go down from the milliseconds to nanoseconds or microseconds, it would be over a tenfold increase in speed and I wouldn't need 10 machines running in parralel to do the job in one day (which unfortunately I don't have
Most application are bandwidth hungry, but there are some stuff out there requiring LOW LATENCY, and heck, if there wasn't a need for that, you wouldn't see solid state drives for 60,000$ out there. There's a need, but sometimes you're limited by your R&D budget and you'd gladly take an emmerging technology or home-made stuff if it means saving 80% of the cost of the equivalent part, and increasing your effeciency by a factor 10.
I'll see your answer "if you need it, and it slows down you r&d, buy it, for the sake of the company" sometimes it doesn't work like that for cashflow reasons and you have to work with what you can get in your specific budget, the issue here (and title of this forum) is about cheap storage that would have a low latency and High bandwidth solution (with loads of storage). I'm sure I am not the only one that would GLADLY grab a 30GB solid state drive for a fraction of what it would cost me with the current systems (which are way overpriced considering the price of ram right now).
There's a need for Solid State, while I understand that the gap between a home user and a workstation/server class machine is blending more and more, it's not because a home user wouldn't benefit from such a device, that it's not needed for corporate or R&d levels. Current solutions wouldn't be selling for 50K$+ if there wasn't a need for them... heck, they wouldn't exist.
--- Metamoderating abusive downgraders since my 300th post.
This can be done, in a usable way, with a steganographic filesystem (one that doesn't just encrypt the files, but encrypts everything, so you can't tell if there are files (or a partition table, etc)).
The other (slightly less secure) way is to use a network filesystem for storage, of encrypted files, and decrypt the files in memory on the diskless desktop computer as you were using them. That way the decrypted files couldn't be written out in swap, or any of the other common problems. Once the power was turned off, it'd all be gone. But unlike most systems, the decryption would all be done locally, preventing clear-text from ever being transmitted.
Ideally your BIOS's POST routines would involve multiple writes to RAM, of patterns and psuedo-random data. So you'd just hit RESET and it'd perform a thorough wipe. (Theoretically data can be recovered from RAM once the computer is off.)
Even 20% speed increase in compilation time is worth it for me...
;P)
Would it be? How long does a compile take? Do you do anything else during compile time that would take away time from the other parts of your day (like, oh, reading slashdot
My full compiles take about 10 minutes for my module, and I do them maybe 5 times a day, max 10. Saving 2 minutes per compile will save me 10-20 minutes a day, which is nothing. I also do many spot compiles of individual files which take very little time at all.
And during those 10 minutes I read my slashdot, I go to the can, I gab with some coworkers and impact their performance, I surf the web, I gab with my boss, I keep happy. I'm very HAPPY to be given a good excuse for many 10 minute breaks a day, I dunno about you =)
If God gave us curiosity
Agreed - we aren't there yet and I doubt that we ever will be. Platter disks are still lots more expensive than RAM. Quick check of my favorites shows PC 133 SDRAM at $.07-$.9 cents per MB and big IDE drives at $.002-$.004 per MB. That is roughly a 20X-40X spread. This is an order of magnitude improvement from the 300X or so spread mid-90's when memory was $100/MB and disk was about $350/GB.
So hybrid RAM/disk solutions are desirable. But RAM does not automatically equal performance. I had an interesting conversation circa 1995 where Mike Karels (of BSD fame) talked about how you were lucky if hard drive caches didn't slow down the drive. The real performance of real file systems is a very complex problem. Subsequent to this we did some random benchmarking at the time and found about a 50/50 split where disabling the read cacheing would speed up rather than slow down real I/O performance. Part of the issue is that many drives embedded processors were not very fast so the hit of maintaining the cache was worse (since the disk to interface data path was usually a seperate fast path but cache would hit the embedded CPU).
In most OS/Filesystem combinations a file open/inital access is very expensive - lots of little I/Os to chase directories and file allocation chains until you finally get the data - then maybe a big read-ahead for you buffer cache that may or may not get used. Most filesystems are better at some things at the expense of others. So whether some amount of caching saves you any real elapsed time on an actual I/O operation is highly variable. There's also been discussion about how many filesystems (like UFS) were originally designed to try to factor in optimizations to deal with things like rotational latency and transfer speed based on rotation - that all goes out the window with any modern hard drive using zone recording/constant angular velocity (see http://www.isi.edu/netstation/zcav/zcav.html).
Right now transfer speed of the interface is a big limiting factor, as drive density goes up more and more drives can fill the pipe-at least on the outside tracks. So without new - and incompatible - interfaces you are likely to see less and less performance wins from a RAM based disk versus platter based.
IMHO - I think real wins in storage performance need to come from greater abstractions in the storage model. Imagine a device that you gave a complete path to and it then gave you a byte stream - let it manage the consistency, metadata etc. In some ways this is happening. Look at NAS versus SANs.
Network attached storage is better performance using interfaces with higher and higher bandwidths (GigE, USB 2, Firewire, Infiniband) so that it gets closer to performance with local storage.
Meanwhile local storage looks more and more like a network and has more and more features than simple block read/write (look at Storage Area Networks) - so the convergence is close in many ways.
I think real persistant storage will be using platters for a long time - until some new paradigm comes along. Look how long it's been since the venerable "Winchester" drives replaced drums, tapes, cards, etc. The RAM will be used where it's used today - as memory for CPUs to provide more intelligence and caching.
Here is a reality check on the practicality/feasibility of large capacity solid state storage...
***Performance: People here seem to be underestimating the performance of caching technologies. There are a number of cache levels on your PC (hard disk cache -> system ram -> L2 -> L1), and each one does a pretty decent job. Don't believe me? Create a large RAM disk and fill it with some typical applications, then start playing around. Your OS does a good job at keeping large areas of relevant data in system memory. You won't notice a huge boost in performance in everyday computing, except in limited circumstances. Granted, some of those "limited circumstances" are quite useful... You would, for example, be able to copy 1GB of multimedia files on the order of seconds instead of 1-2 minutes.
The key advantage of solid state storage is latency, not raw transfer rate... Latency plays a big role in overall system performance, and the near-instantaneous access time of an "SDRAM disk" could spell large performance gains in certain classes of applications, but it is NOT the end-all solution for increased PC performance.
***Power consumption & volatility: A number of people have posted that SDRAM is volatile. Well, duh, "just put a battery backup on it." Unfortunately, a number of issues come up when you try to do this. In the old days of DRAM, the DRAM controller or chipset would have to refresh the DRAM array on the order of 10-100 times per second. Remember, DRAM is capacitor-based storage, not transistor-based like SRAM or caches. Constantly refreshing these old chips requires constant power, and a lot of it.
Now the picture is somewhat brighter... Modern SDRAM chips have relatively low-power (8mW per chip), self-refresh modes which allow them to hold their contents without an external controller -- you literally just keep power supplied to the chip, and it will retain its contents.
Getting back to the point... Consider a 10 GB SDRAM disk. The largest volume-production SDRAM chips have 256mbit (32 megabyte) densities, and thus your 10GB drive requires 312 SDRAM chips. The number of chips itself may become a board integration problem. Also, good luck maintaining signal integrity at 100-133 MHz when your traces are 5 inches.
But for now assume these problems are solved... The real problem is power consumption in a "computer is off, my data is staying put" mode. Typical 256 mbit SDRAM chips consume about 2.5 milliamps during self-refresh, and so if your computer was off you would need 780 milliamps (2.5 *watts*) of continuous current simply to keep the memory contents intact! This would eat a $200, high-capacity 56 watt-hour LiIon laptop battery in a matter of 10-20 hours, so what would it do to some AA's from radio shack?
There *are* lower power SDRAM chips hitting the market (micron has some "battery friendly" SDRAM chips that draw much less than 2.5 mA in self-refresh mode, but they are FAR more expensive), but the issue remains.
So, in reality you need a hard disk that complements your SDRAM-based storage which keeps a copy of the data at all times.
***Reliability: Another issue is SDRAM soft errors... As SDRAM densities have skyrocketed and we move to 0.13 micron (and lower) fabrication processes, alpha particles hitting the die are becoming a problem. So, error correction is obviously a problem, and this would need to be solved (increasing costs and feasibility) in order for SDRAM-based storage to be as reliable as hard disks.
***Cost: Just because DRAM is unbelievably cheap now, don't assume it will stay that way. DRAM manufacturers are taking huge loses just to stay above water. My prediction -- once (if?) the economy recovers, you will NOT be seeing 1 GB of SDRAM for ~$60 anymore.
And even now, SDRAM-based disks could have their niche applications, but as long as hard disks stay so far ahead of RAM in terms of cost ($60 buys you ~40GB of disk, 1GB of RAM), I cannot see them becoming mainstream.
-Mel Tsai
They've got two main product lines:
Their devices are supported on Sun/AIX/HP *and* Linux *and* FreeBSD, which makes it great for anyone who wants more speed from session caches and database logs.
Another issue that has been overlooked is the size of the resulting RAMdrive. You can buy 3.5" drives at 75 gigs. All of the current products that I have seen are at least full sized PCI cards, or a PCI card controller connected to a seperate RAMdrive frame.
The amazing thing about this is, the spinning storage is smaller that RAM drives. This is quite counter intuitive, but I believe that it demonstrates what engineering marvels a state of the art disk drive really is.
I do believe that RAM drive/ RAM storage technology can achieve mich higher packaging densities, but not using today's off the shelf memory chips.
-tpg.
I remember way back some of the guys I worked with at DEC Research had an Evil Plan(tm) to try to buy a bunch of RAM that had been culled at a fab plant. Apparently there were plenty of chips that "almost" worked but weren't fast enough (e.g. 100ns RAM that didn't work at 100ns but worked fine at 300ns...) or didn't store all the bits - the idea was to run them slower and keep parity for lossage. Interesting idea, anyhow, though I bet it'd be hard to get a microprocessor maker to sell their "seconds" - since they're "garbage" at that point, though, you could get 'em cheap, in theory. ;)
mjr.