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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?
You would still need a stable flow of juice to keep from losing everything in case of a blackout or something. I'll stick to the platters for now.
icksnay on hacking my boxsnay.
where's that Ralph "Jew Hater" Nader guy?
Not that I want to see him return, just wondering.
Slashdot, come for the goatse, stay for the trolls.
Huh? Unless I'm completely out to lunch, I don't see this....
Is my math wrong, or is Cliffs?
In fact, the Klan is the good nigger's best friend. If the nigger will devote his energies to becoming a better, more useful nigger, rather than the dupe of Northern interests who have caused him to misconstrue his social standing, he will reap the rewards of industry, instead of the disappointments of ambition unobtainable!
Southern whites, occupying that super-position assigned them by the Creator, are justifiably hostile to any race that attempts to drag them down to its own level! Therefore let the nigger be wise in leaving the ballot in the hands of a dominant sympathetic race, since he is far better off as a political eunuch in the house of his friends, than a voter rampant in the halls of his enemies!
Imagine the size/number of boards that would be needed to get 80 GB of storage. It may be quicker but engineering something that is feasible would quickly drive the cost up so that it wouldn't be that cheap. Further, the cost to modify existing controller technology or making a RAM drive fit the current controllers available. Then there's all kinds of other technical issues like power.
Of course we torture people, we need the information --Gen. Pinochet
Secondly, STFU with this "most boards won't support more than 2GB" bullshit. Yeah, sure, on your lame little x86 box. You can easily find 4GB x86 server boards, and this is assuming that you want to confine yourself to such a lame architecture. With the release of StarCat, Sun E10Ks will be dropping in price soon, and you can put 64GB of memory in those babies. Of course, with cheap 64GB IDE drives becoming more common and 64GB SCSI drives (i.e. real hardware) can be found for the right amount of money.
This story perfectly exemplifies the shitfucked asscrap that is Slashdot today. I hate you all.
--
I like to watch.
Given the plummeting price of high density/small footprint hard drives, you could have both the volatile drive and the nonvolatile drive in a single low price unit, with backup to/recovery from the nonvolatile drive occuring automatically on startup and shutdown.
It needs to be more often than startup/shutdown! Many of us don't shutdown for weeks at a time. You would want it to continually copy things to the disk when there is idle time. But then you're essentially using the RAM as a really big disk cache which is where we are already today.
As I read the article, the whole point is to shift to RAM and save money at the same time. If you're buying the hard disk anyhow then you're shifting to RAM but not saving any money. And you may not be improving performance much over a massive RAM cache either. So I find it hard to be enthusiastic about this idea of backing up the RAM to hard disk.
The slashdot crew over the past few days/weeks have been extremely out to lunch, has anyone else noticed this?
/. or Salon.
/. gets over 200 story submissions per day, and yet the average number of story postings has gone way down, now to about 10/day. What's going on here?
Example 1:
but RAM is now cheaper when it comes to memory-per-unitofcurrency than hard drives -- cliff
RAM is 30-40x more expensive than HDs, I don't know WHAT he was smoking when he thought that...
Example 2:
I suspect a fair number of people never try Linux or one of the BSDs because they're moderately happy with AOL as an ISP -- timothy
how many people do you know who would be running Linux if it wasn't for the fact that they were using AOL? (Let me rephrase, how many tech savvy people are using AOL (that aren't forced to)?)
And the anti-Microsoft hysteria has been especially harsh over the past few days. That article about File Extensions And Molopolies was so pathetic it didn't even qualify as satire. It should never have seen the light of day on either
And
If God gave us curiosity
There are two ways you can do this.
Way 1 -- Use a PCI card with 4GB of RAM on it as primary storage. At the end of the day, or week, or whatever, copy all of the data to more "permanent" storage. Like hard disks. This way a power loss (or battery failure) isn't too much of a nightmare.
The drawbacks are that you need special hardware and you could lose days of work.
Way 2 -- Cram your machine with as much RAM as possible. Which probably means 4GB. Configure your OS so that it uses about 95% of RAM as a buffer-cache.
Data will be loaded from disk initially on demand (which means slow startup) but will almost always stay memory resident thereafter. The OS will also commit dirty pages back to disk from time to time ensuring that you don't lose anything important.
This may be less doable with systems that insist on synchronous writes during file operations, but you can often disable these things if you want to take the risk.
The benefit of this approach is that you don't need special hardware and you're less likely to lose data than Way 1. Which basically means you can and have been experiencing this now.
If your system grinds disk consistently after several hours of use, it's a good indication that you should get more RAM considering how cheap it is.
Hopefully, this technology will still be made available to those of us who don't need a 100GB hard drive.
Unfortunately, that is very unlikely due to economies of scale, and price compression. Take a look at hard drive prices. Try to find a 10GB hard drive these days, and you are likely going to pay more for it than for a 40GB drive.
In the same line, look at the prices for currently manufactured drives, and processors. The price for the newest is astronomical. The price for older stuff drops, but not linearly. It slowly hits a plateau (it's nice that the whole curve seems to be lowering) currently near the $30 mark.
There just isn't a market for "slow" (less than 600MHz) processors or "small" (less than 20GB) hard drives. While I really like the idea of an UDMA100 4GB drive, (solid state would be even better), there just isn't a viable market for such devices.
What's the mtbf on Solid state drives?
Well, it can't be worse than the MTBF of IBM GXP drives..
Plus, it's pretty much a given that MTBF(device_with_moving_parts) is less than MTBF(device_with_no_moving_parts). You probably had more hard drives fail on you than memory chips, right?
So I think the only problem regarding reliability is solving the power issue to the satisfaction of the average induhvidual.
I think 10 more years max, and then it's the way of the dodo for our spinning friends.
Yan
I think this line's only filler
If you're updating the platters in the background, then you're using the memory as a write-behind cache.
Now explain to me how this is different from using main memory as a VM cache in unix?
Ben "You have your mind on computers, it seems."
look at the stats idiot!
80-100MB/s sustained data output.
Which is what 2 or 3 HDs on a software controlled raid can give you for MUCH MUCH cheaper.
If God gave us curiosity
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.
That may be better for some applications. No amount of RAID magic though can reduce the latency though (seek time). So this might be good for some database apps, but a RAID would be better for streaming the data. Though, I can't think of very many apps that require a single 80MB/s stream.
Trees can't go dancing
So do them a big favor
Pretend dancing stinks!
- Ram is so expensive that having it sit idle is a waste of money and time.
- Operating systems do an excellent job of keeping most recently used (and hence most likely to be used again) data in memory
- Keeping files on a ram disk prevents the operating system from using it
To learn this initially, I took a machine with 512mb of ram and made a 100mb ram disk partition on Win2k. I needed to speed up my compile times (>45 minutes) when using a bad cross compiler to the Nintendo Game Cube and a lot of templated C++ code (I didn't write it). After moving all the source code and object output files and executables to the ram disk volume, it turned out that it went even slower than before. This is because less ram was available, so it swapped out more frequently. Same principle applies when just adding more ram. The less you hit the hard drive, the faster your machine runs.The only reasonable purpose I can think of for a fast ram disk is if you can get some relatively slow ram on that device, which is cheap, but won't fit on your motherboard due to it requiring faster/more expensive ram, such as RDRAM or other exotica like ECC Registered SDRAM. But it's still cheaper to get a few hard drives.
Any connection between your reality and mine is purely coincidental.
I see some people debating ram disks.
The way I see it, the kernel is smart enough to use ram for buffering when it can - certainly smarter than a user creating a ram disk.
If you need more performance, give your system more ram and let the kernel decide how much of that ram should go to a ram disk.
I can't think of very many apps that require a single 80MB/s stream
Neither can I, which is why you're not going to notice much of a difference by using a RAMdrive quite yet, and as I worked out it's actually 50x more expensive (per MB) than a 4x75GB HD + HPT 380 Raid controller solution, and the only benefit it gives is less latency.
If God gave us curiosity
is basically how caching works. It's already done.. it's not something new. Linux does it. Every OS does it.. even windows...
The only difference is things aren't cached until they are loaded the first time.
If your computer had 80GB of memory, you would invariably end up with most of your HD (at least, what you were using) cached.
While I really like the idea of an UDMA100 4GB drive, (solid state would be even better), there just isn't a viable market for such devices.
That's only considering a total replacement of one technology for another. In the same way that hard drives didn't make tape drives obsolete I doubt that solid state would make something else less desirable. For example, a 4 Gig solid state drive would be plenty for the vast majority of users to load their software onto. Data could then go to the old platter style hard drive. With a combination of the two you would see some truly astounding system performance increases.
The good news is that the Unix directory structure already provides a great deal of seperation between user data and the programs that access it. The bad news is that Windows does no such thing across the board. Whether you care about Windows or not, it is the OS that's driving the majority of the hardware market out there.
I'm no fan of Apple, but they may be the only folks out there that might pull something like this off. Assuming OSX utilizes a similar seperation between software and data, they have the hardware and software ability to work something like this.
The line must be drawn here. This far. No further.
All you people who keep talking about power loss, think rechargeable battery...
Magnetic storage can sit (unconnected to any power source) for years and years and still maintain data integrity. Keeping several GB of RAM powered reliably and cheaply for that long may not be as practical.
Faster? Flash is hideously slow for random access, because it's impossible to set a bit to '1' without setting the whole 16k chunk (or whatever segment size you have) to all 1s
You must be king idiot then
I'm sorry but you really need to go back to drive technology 101
Idiots like you shouldn't talk out there ass so much...
You must be one of those who
I'd call you stupid names back in return, but I don't stoop that low. Anybody who needs to do that (a) needs a lot more fiber in their diet and (b) needs to lighten up.
I HAVE a 4x75GB IDE RAID 0 array, and can get a max of 98MB/sec read off of it, and a good 75MB/sec sustained. Off of a single drive I can get 45MB/sec max, 25MB/sec sustained.
And I was implying that there are very few applications that need the use of that specific RAM disk over a much cheaper IDE raid array. If you had 4GB RAM on the mainboard, or 8GB or 16, then you would see a few more apps that would benefit from that performance. However just about any home user, and the vast majority of corporate users wouldn't benefit one bit from the use of that. There are very few uses that would benefit from a sustained 90MB/sec, however the very low latency is a big help.
So I wasn't "talking out of my ass". Go shove your nasty attitude up someone elses ass. Like we don't have enough problems to stress over as it is. Lighten up.
If God gave us curiosity
Noise Pollution
You could just use a "ram drive" as a cache to reads off a hard drive and as a small buffer to write to the drive. With a good ups and shutdown software you could get the stuff written to disk before any major problems.
-- Tim
TKrabec Pahh