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Serial ATA Technology Explained
Mike Parsons writes "Explosive Labs has an interesting article on Serial ATA . Here is a quote: 'In the rapidly moving computer industry, there are rarely the kinds of revolutionary changes like what is about to take place in secondary storage segment. Soon the hard drives and configuration methods that have existed since the origins of the personal computer will change forever. The basic IDE technology has been around for nearly twenty years. When the lifetimes of other computer components like CPUs and video are measured in months, twenty years ago seems like prehistory.'"
So...why don't we use firewire? Isn't it faster than SATA? And the upcomming Firewire IEE 1394b should double the firewire speed to ~800mb/s. And let's not forget the fact that there are firewire HDD-s and other perhipeals on the market (though they are generaly external) or maybe, could this have anything to do with INTEL's desire to controll all components? I don't see the price as a limiting factor either.
Live for the present, learn from the past, and dream of the future!
The author then goes on to note that the 'roadmap' calls for the 2006 version to run at 600mb/s, which fits nicely with my roadmap to world domination in 2005. ...Ummmm, yeah, we'll see.
Although looking at the list of upcoming products and the manufactures making them, I don't doubt we'll all be useing this in a few years.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
The whole point of it is to be at least as cheap as parallel ATA, even cheaper. The connectors will be smaller and cheaper for example. It should also make system design more flexible since you won't have parallel ATA's infuriating cable length limits.
For that matter, how long has the x86 architecture been defined? How many /. readers were even alive when the 8086 was released? I know I felt a few grey hairs pop out when a co-worker told me his first computer was a 286. Only superficial changes in computer architecture have happened during our lifetimes. The way we interact with computers is totally archaic, just like the way we interact with banks, cars, washing machines, and televisions is archaic. The world is dying for some clever person to come up with a way to make it just as easy to ask a machine to do something as it is to ask a person to do something.
On stereophonic equipment, the monaural sound obtained through multiple channels will enhance your listening pleasure.
"All of IDE's shortcomings are fixed by SCSI (except for a small degree of added complexity)."
Yeah, even if your statement were true. Price is a huge shortcoming in technology today, especialy when most people can't use the preformance hardware that they own.
I strongly support the development of IDE standards. There are many situations when you need lots of hard drive space without bleeding edge preformance. Try to find a solution for doing a small (350GB) backup server to add to a tape backup system, you find 200GB IDE drives for the price of a 18GB SCSI drive. A thousand people will try and explain why the SCSI is a better deal because its more reliable and faster, but backing up 350 gb on IDE costs about $650, and on SCSI costs aboyt $4000. I don't believe the demand is the reason for the premium price for SCSI, but the hardware... It's just more expencive to make.
Yawn.
All data goes through the PCI bus...and it's bandwidth is only 133MB/sec theoretical. So, what does 400/800/anything else greater than about 100MB/sec in a media interface get you? Not much!
Ever read the actual throughput specs on a drive? The media throughput is not much more than 40MB/sec!!! Read the data sheets, people!
Add this all up and what do you get? Ripped off is about it!
> You mean the oversized 40-conductor ribbon cables are solved by 68 conductor ones?
No, I'd guess the 80 pin ones that include power and configure the drive's ID, and allow you to just slap the drive in and let it go. IDE has NOTHING with that configurability.
> You are the first SCSI fanboy I've ever seen.
Now you've seen two.
Don't get me wrong - for home use, SCSI is overpowered. But if you're talking anything bigger than a desktop, make mine SCSI.
This sounds remarkably like the plugs we got for Rambus RDRAM: serial interface is better than parallel, first gen won't see real performance gains, stick with us kids, this is gonna be really good.
I see a decided lack of Sun, IBM, AMD, or HP listed in the adopters, which leads me to believe that this is much like the above. Sorry guys, I'm not riding the first wave of any new tech on my salary. I'll sit on the sidelines for awhile and see how this pans out.
Wu-Tang Name: Half-Cut Skeleton Get your own Wu-Na
For the time being, IDE isn't going anywhere.
NOISE & HEAT will tend to outweigh (relatively) minor performance gains in consumer systems. (Enterprise hardware is another matter entirely)
sigh....we need to start using those annoying javascripts that make people read the article BEFORE posting.
When in doubt, parenthesize. At the very least it will let some poor schmuck bounce on the % key in vi. (Larry Wall)
I've been waiting for Serial-ATA ever since reading about it. Faster speeds/bandwidth - which is actually finally needed in the IDE type world.
:)
... I could see easily wanting a tall tower (remember those?) and building a rock and roll back end storage system for personal use. Quick and cheap ... and now VERY EASY to do. Personal RAID-50 500G personal array anybody?
... even with el'crap-ola IDE no-warranty technology.
NO MORE RIBBON CABLE. My favorite Linux configuration is 1 whatever IDE drive for the OS, 1 IDE CDROM, and two (RAID-1) large IDE's for data and configurations. Quick and cheap for non-critical type functions/services. I rolled through a complete failure on the core OS drive, CD died -- while trying to roll up in size on the RAID-1 and hit *FOUR* defective WD drives...while never losing data _and_ configurations. IBM sits in there right now...
High end servers and workstations? Yeah, Serial-ATA is nice with the coming 40M/sec IDE type drives...but I'm also going to go after that 320M/sec SCSI technology too. Same IDE game, just a different connector basically.
NO MORE RIBBON CABLE.
Try stuffing four drives in a case. Not only is the IDE chain full, but cabling is a complete joke. Not anymore. Kind of like Firewire in the box, if you will. Except I think their screwing it up and keeping power separate where Firewire _can_ cary power to the devices.
So instead of tiny IDE connectors in the current Firewire and external type drives there will be tiny Serial-ATA hookups. So what. Now get inside a PC (and/or Mac) and do a little work.
With this and pricing for LARGE amounts of data
I could record so many hours of anything I wanted and never worry about losing it
Of course when I have a few extra thousand lying around (not likely any time soon with the current economy outlook) I'd love to try SCSI-320.
Now, IDE is rolling into ~40M/sec. Firewire *has* been ready for those speeds for a while. At least USB2 can keep up for a bit as well. Even faster drives is a must though. Firewire-2 is just around the corner (either 800 or 1.6Gbit's).
It's sad that your typical/standard Mac type network (1Gbit) is faster than the typical drive being hosted. Your typical Windows network at 100Mbit is pretty muched caqpped by the current typical drives top performance at 10M/sec.
Serial-ATA, oh yeah. One card (1Gbit) in the Linux box and I could saturate their bandwidth. Why not?
Microwho?
>I would like to say that the price of SCSI drives is not 10x more because nobody wants a SCSI drive, but because they are simply more complicated to manufacture and interface.
That was true in 1980. It isn't now. I mean, it costs no more to build a RAID card (witness Promise Ultra Hack) than it does to build an IDE card, and that's massively more complicated than SCSI.
In fact, since all the smarts are moved onto the controller (which is dead simple to make today -- I bought a cheap one for $35 CDN two years ago -- it was cheaper than a cheap IDE card!) the drive itself is less complicated.
>Also, the preformance hit you take going from 7200rpm SCSI to 7200rpm IDE is not noticable at most times, but I suppose i am tolerant because i can wait more than 3 ms seek.
Agreed, but there's more to it than that. IDE requires new interfaces every drive (unless you want to take the horrible performance hit master/slave arrangements incurr). SCSI doesn't. IDE cables can only be 18". SCSI can be quite a bit longer. IDE only works for hard drives and CD-ROMS (and one or two other things). SCSI is for anything. There's more reasons than this to support SCSI over IDE (at the same price), but I think these three would be enough to sway users at the right price.
>SCSI is loud and hot and expencive, just like all preformance computing componants, and thus will never be a consumer standard.
Only because no manufacturer thinks there's a good market if they slap a SCSI controller on their current consumer hard drives. I think there is, and I'd be game to buy one, if they existed, for my next upgrade.
If you could be told what you can see or read, then it follows that you could be told what to say or think - BoC
It's real simple, ribbon cables SUCK, they cost more to make then serial so PC makers hate them.
So, here's how it is...
Fibre Channel - 2Mb/s(10Mb coming very soon), 126 drives, 10+ mile range, better then SCSI.
S-ATA - 1.2Mb/s(2.4Mb in 2004), 18" range?, IDE protocols for all your write-only data needs.
S-ATA is the Ghetto FibreChannel, just like IDE is crappy SCSI, expect similar suckiness and low quality to go with the low price and cheaper cables (to make, to buy they will cost more I'm sure).
But again, this is all about the creaper cables, since lets face it 95%+ of the machines out there only have one drive anyway.
- Adam L. Beberg - The Cosm Project - http://www.mithral.com/
You can stick a parallel to serial adapter on an IDE drive, reduce the cable size, but it's still a crappy IDE drive.
:)
... but assuming you could still use all your exiting hardware it would be about that exciting.
If IDE hardware developers read slashdot, here is a list of IDE problems I'd like to see fixed.
1. You can't HOTSWAP an IDE drive without risking blowing your drive, crontroller, or upsetting the powersupply.
2. You can't WARMSWAP an IDE drive, without risking blowing your drive, controller, or upsetting your powersupply.
3. IDE still only supports 2, yes 2 drivers per controller, which makes it impossible to do hardware RAID-5. That leaves us with software RAID-5 as our only option.
4. IDE cables can only stretch so far, so even if you could somehow manage to get 8 IDE controllers into a box, for a total of 16 drives, there would still be cable length issues. I think 1 m is max. We need differential IDE
5. IDE drives are just now able to verify data integrity, but thats good since we can start using IDE drives in servers that don't need 100% uptime.
6. ATA/100 Round IDE cables are already available. In fact I just ordered some that have a UV reflective coating for my next case mod which features a black light. Airflow isn't a big issue, in fact Compaq has been slicing up IDE cables for a long time now to increase airflow.
7. The SUSTAINED TRANSFER WRITE RATE of IDE drives is still not fast enough to store uncompressed NTSC video at 60 frames per second, or store high bandwidth Satellite streams.
8a. Size increase (GB's) are not keeping pace with read/write access speeds and simply adding cache RAM and tweaking seek algorithms isn't going to remedy this problem.
8b. As, internal volatile write caches grow larger, the risk of uncommitted writes being lost in a power outage or crash increases.
If serial ATA would let me connect 4 drives per controller, I might start getting excited. If I could start "hot swapping" IDE drives, I would get really excited.
However, going from "flat to round" and "parallel to serial" is about as exciting as Windows XP compared to Windows 2000. It does the same thing, only slightly different. Actually in the case of Windows XP, thats not true, since Windows XP is missing device drivers for older Digital Cameras, Scanners, Modems, Video Cards etc
...and one reason only:
To get rid of those damn ribbon cables.
Don't believe the marketing hype. SATA isn't about faster speeds, or more advanced features, or any of that crap. S-ATA is about cables.
IDE is crippleware. At some point in the past there was probably a need for a simpler, less expensive counterpart to scsi for desktop systems, but frankly that need is gone. The price distinction between IDE and SCSI has long been totally artificial. Drive manufacturers make a drive, and then slap on whatever control board they need, IDE or SCSI. Makes no difference to them, except that they get to mark up the SCSI version. Pure marketing: they need to stratisfy their technology so the enterprise guys don't feel like they're sullying their hands with the same tech as those Walmart PC-consumer lusers.
Frankly I wish SCSI had those neat little connectors (and they soon will, with Serial attached SCSI), and I hate ribbon cables as much as the next guy, but I'm not going to be fooled into thinking this is any real improvement over IDE.
But even as little as this is, it's long overdue. Those ribbon cables are the enemy of all that is good and just and true in the world.
Remember folks, SATA is only one letter away from SATAN. Q.E.D. Evil.
This seems to say something that I've never seen admitted about serial ATA: that it has DRM built in! If you want to buy hard drives that get to decide what you can and can't store on them, go ahead, but I'm not going to buy into any DRM technology. Extra speed and a smaller cable will not tempt me into doing it; I'll stock up on the last of the regular ATA drives as the serial ATA's replace them.
I'm an American. I love this country and the freedoms that we used to have.
Firewire 400Mb/sec
USB 2.0 480Mb/sec
SATA (I) 1.5Gb/sec
Best use for hard drive:
SATA
Firewire
USB 2.0
Why firewire over usb2, Firewire is designed for low latency applications such as streaming video or for using hard drives. USB 2.0 is not, as soon as you add another device to USB2 your drive suffers horribly.
1 device per interface is the way to go for high speed interfaces - you don't have signal reflections limiting the speed of the interface. It is like having multitaps on the cable TV - the more you have, the poorer pictures you'll get. Remember 1.5Gbps is the first stop. Having multiple drives with multiple 1.5Gbps links are nice.
1m is about the right length to go outside the white box PC into an external case for external drives. I would love to put all the drives in a well cooled case for extra reliability.