And now a few words about the cable length. SATA standard limits the maximum cable length as 1m. And all promotion materials present it as an advantage. But can you imagine my astonishment, when I opened the boxes with SATA controllers (regular ones and RAID ones) and saw the cable pieces of the common 45cm length. What a swindle!
- Compact connector.
Now all the big and broad PATA connectors will be replaced with a bigger number of compact SATA connectors.
Yes, the connector has become smaller. From the user’s point of view it means only one thing: it has become harder to plug the cable in. Especially is the PC has already been assembled. The cable connector plugs into the mainboard connector really easily (if you aimed well, of course :), however it quickly loosens the connection between the cable and the SATA device, which seemed so secure to you a minute ago. Since there is no lock on the connector, the rigid cable immediately distorts the connector, so that you need just to shake the PC during transportation, for instance, to lose the contact completely... In fact, the old bigger PATA-connectors provided a much more secure contact due to extra friction...
- HotSwap and HotPlug
The opportunity to connect and disconnect HDDs on the fly is a significant improvement. If you wanted to be able to do HotPlug with the ATA hard disk drives, you needed special mobile racks. Now the HDD connectors and electronics are designed to support “safe” HotPlug.
Well, I don’t have any arguments against this feature. The only trifling exception is the fact that the today’s operation systems hardly support the real HotPlug. All this is very relative.
SATA protocol guarantees that every byte of information will be transferred along the cable, unlike ATA/ATAPI6 standard, which provides the check sum only for the data and the commands are all transferred trusting to luck.
- High speed.
Another serious advantage of SATA interface is very high data transfer rate between the HDD and host-controller. With SATA we will finally be able to forget about the Master-Slave concept, so that each SATA device will not split the bus connecting it to the controller with any other device and will have its entire bandwidth at hand. And it is exactly 150MB/sec.
However, until SATA controllers get embedded into the chipset South Bridges, they will have to use the PCI bus to access the memory, which means that we will never get the desired 150MB/sec from the SATA HDD. Moreover, we will not squeeze the sacred 300MB/sec from two SATA drives working in RAID 0 array! Of course, there are mainboards with PCI32/66MHz bus but they are very few...
On the other hand, contemporary hard disk drives can transfer the data at this maximum speed for a pretty short time in a row: until their cache is empty. And as you understand, this will happen very quickly. So, we do not actually need 150MB/sec bandwidth nowadays, so you can regard this feature mostly as a good thing for future products.
Since we came to speak about the future.... If I haven’t yet scared you with all this discussion, I think it’s high time I slowed down with my anti-SATA arguments and cast a glance a few years ahead.
Imagine a computer of the end of 2005. A mainboard with an unbelievably powerful CPU. The processor bus frequency equal to twice the contemporary one, but the mainboard layout didn’t get any more complex, because the developers do not design 32 pins for each ATA connector (16 for data and 16 for control signals) any more. Now they are laying out only 4 signal lines for each SATA connector!
The HDDs have acquired new 2.5” form-factor. The interface used is SerialATA II, of course. The HDDs are no longer powered directly from the system PSU, but are connected to special plugs on the mainboard. This allows to same some power by shutting down the HDD motor if it is idling.
Hm, looks very attractive, don’t you think so? Well, since we are really anxious about it and are not used to keeping our hands in pockets, let’s try to find out what can we get from SATA interface today already:
- Thin servers will finally get a convenient way of using ATA HDDs;
- The users will finally get a relatively easy way of assembling HDD arrays of multiple drives;
- Chinese manufacturers of HotSwap mobile racks (which look more like portable coffins for HDDs) will lose their customers;
- The users will get theoretically faster drives (due to faster interface).
Well, this seems to be all I could think of so far.
Now let’s have a closer look at the new generation hard disk drive.