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Serial ATA Coming
John Doe writes "Heatseekerz.net Has a new article dedicated to Serial ATA @ Cebit 2002. This technology will be here sooner then you think!" The article is a little thin, but I haven't heard
a lot about what looks to be a very common standard in the not so distant future.
Firewire is so cool, they should just use it for hard drives also.
Integrate the controller on the motherboard if you have to.
to compete with the firewire (and upcoming gigawire) "standard" and the usb 1.x and 2.x "standards". oh and we have ata/133/100/66 "standards". scsi 1/2/3/4/5/ultra/wide/thin/mega-super-fun "standards" too.
how come none of my "standard" devices talk to each other very well?
well three cheers for the latest "standard". by the time it's on everyone's hardware it will be superceeded a dozen times or so.
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Other than the touted 600Mb data rate versus 400Mb for FireWire, I don't see any real advantages to this new standard. FireWire (aka IEEE 1394 is already planned for use in internal devices, and it looks like a competition footrace may emerge between SATA and FireWire. Because of Apple's noted efforts in founding the FireWire project, It will be interesting to see what side Microsoft will support the strongest.
Ok, let's see here:
For 1), I have heard that, indeed, power and data are together in a single connection, or at least it is tandardized to make hotswap feasible.
2) This is completely false, one of the main points of *serial* ATA was to increase the chain lengths to SCSI level capacities. The focus is on software compatibility, not transparent hardware compatibility. They say in the beginning, they expect motherboards that have Serial ATA to also have Parallel ATA on the same motherboard...
3) Why is it not usable for external devices? For one, they have extended cable length to three feet between points on the chain. No where near SCSI capability, but three feet from an interface card isn't bad. I suspect you could at the very least have SCSI solutions in ATA with this.
You are right that FireWire or USB2 might be worth a second look, but at the current rate, no one wants to bother scrapping everything they have based on ATA to pursue such a dream. I would much rather have Serial ATA than our current ATA. Of course, I have to wonder if the industry will even see this move as worth it. Even if from a software perspective it behaves similarly to ATA, I would think the hardware implementers have been holdig back. ATA is seen to meet the demands of home users, and SCSI supplies advanced features to businesses that need it. Hardware vendors have a vested interest in maintaining that dicotomy, since they can charge a huge premium for SCSI without problems coming up in the Desktop market...
XML is like violence. If it doesn't solve the problem, use more.
From 1, you can't hot swap with a cable. Hot-swap requires a backplane. How you get power to the backplane is up to you. They have two connector styles. One standardizes the location of the old style power connectors, then they provide a single connector for power/signal, just like SCSI did, but they do not run power off of the adapter card and into the signal cable. If you are designing a backplane for drives, then you'd use the same connector, but that is different from the same cable.
2. This is incorrect, the signalling is shorter, and sATA does not want to compete with SCSI, in the future, SCSI and sATA will use the same interconnect and you choose based on how much money you want to spend. SCSI runs 25 meters point to point while sATA is 1m.
3. Nope, the distance is still 1m. No extra length. It is possible to change the spec a bit and give distance, but what would you run it to. Since it is point-to-point, and the software stacks can't handle more than two devices on a bus, what would you connect but one drive, or possibly two with a special chip?
SCSI is offering a compatible solution at http://www.serialattachedscsi.com
It is important to remember that products cost as much as the consumer is willing to pay. SCSI costs more because it still has a performance advantage and people are willing to pay it.
ATA is cheap because a lot of it is sold, and it isn't as high performance.
FC is still very expinsive because only a few larger organizations want it, and it is difficult to administrate, but it serves a purpose.
sATA will probably steal a bit of share from SCSI in the low end server/workstation market where only 1-2 drives are used. But these servers would still benefit from SCSI, the value add though is not enough to justify the higher costs. But since SCSI past U-640 will be compatible with sATA using Serial Attached SCSI, the cost of SCSI may come down comparably.
Adaptec has a press release concerning their new Serial ATA ASIC/controller here. I'm sure many other manufacturers have similar news as well.
This is one new standard I'm willing to accept. In fact, I'm a bit surprised by the number of people here scoffing at Serial ATA. With performance of some parallel ATA drives matching mainstream SCSI drives for months now, with capacities closing in, and with SCSI manufacturers continuing to slowly drop production of SCSI optical drives, I think the end of SCSI is near. I never thought I'd say that, but I really think it is.
So to all you people saying that this just introduces a new standard to a "mess", I think you're wrong. This will end the division between desktop storage and mid-level server storage. Firewire and USB will stick around - but only as the external storage interface options they should be.
One of the current limitations of the ATA standard is that maximum drive size is 137.4GB. While we're not quite there yet, it seems like this could become a problem at least by mid-2003.
I'm surprised that the opportunity was missed to address this with the introduction of Serial ATA.
For the curious, the limit comes about since only 28bits are used for the sector number in the ATA protocol. (2^28 * 512 bytes = 137.4Gb).
This is straying dangerously off topic now, but its quite amusing to look at the history of arbitrary hard disk size limits: (from The Storage Review)
PC/XT Parameter (10.4 MiB / 10.9 MB) Barrier
FAT12 Partition Size (16 MiB / 16.7 MB) Barrier
DOS 3 (32 MiB / 33.6 MB) Barrier
The 1,024 Cylinder (504 MiB / 528 MB) Barrier
The 4,096 Cylinder (1.97 GiB / 2.11 GB) Barrier
The FAT16 Partition Size (2.00 GiB / 2.15 GB) Barrier
The 6,322 Cylinder (3.04 GiB / 3.26 GB) Barrier
The Phoenix BIOS 4.03 / 4.04 Bug (3.05 GiB / 3.28 GB) Barrier
The 8,192 Cylinder (3.94 GiB / 4.22 GB) Barrier
The 240 Head Int 13 Interface (7.38 GiB / 7.93 GB) Barrier
The Int 13 Interface (7.88 GiB / 8.46 GB) Barrier
The Windows 95 Limit (29.8 GiB / 32.0 GB) Barrier
The 65,536 Cylinder (31.5 GiB / 33.8 GB) Barrier
The ATA Interface Limit (128 GiB / 137 GB) Barrier
And only four of them are due to Microsoft...
...if you're willing to live with the four-device limitation of Serial ATA...
...eventually see the equivalent of ATA-300 and ATA-600 speeds, which far surpasses even the current Ultra-Wide SCSI 160
...SCSI is still pretty expensive...
Many of us simply can't live with the four-device limitation. SCSI and Fiber Channel shine when scalability is needed. There are many applications for multi-controller multi-drive RAID devices that ATA simply isn't cut out for. It is also nice to just be able to add another device when needed--SCSI is very convenient.
This is comparing something that doesn't exist to something that does. Also, Ultra320 SCSI is just around the corner.
Third, Serial ATA--unlike SCSI--doesn't require you to load device drivers out of the wazoo to support devices on the bus.
This is untrue. One SCSI driver allows me to connect any SCSI device: hard disks, ZIP drives, scanners, etc. The only additional drivers are those needed for non-SCSI devices, such as the parallel port or a modem.
Not in the long-term. Good system administrators are more expensive than SCSI controllers, and the time and frustration saved more than pays for the SCSI controllers.
And in the home, SCSI really never had a foot-hold, so Serial ATA changes nothing.
In short, ATA never really competed with SCSI and never will. As long as ATA is crippled to be useful only in personal computers, it will never appear in big computers, multi-user computers, or high-performance workstations. These are not niche markets, either.
Healthcare article at Kuro5hin