Articles :: Intel Developers Forum: Part 1 ::

Niso Levitas · 03-06-2002 · Category: Interviews

Serial ATA

We have been waiting to see Serial ATA on the market. Everything is ready(according to Intel) and chipset integration will be in the second half of 2003. Working disk samples are around, so I don't understand what they are waiting for. VIA added Ultra DMA 133 into their chipset but most of the disk manufacturers, except Maxtor, didn't buy the idea. We saw that a good UDMA 100 disk may toast Ultra DMA 133 disks. With cable standards, and all "single master"features, Serial ATA is the technology that I prefer, I guess I will have to wait.

Serial ATA is not only taking less space inside the case due to smaller cable sizes, but dramatically increases free space on the motherboard as well. Smaller and cheaper motherboards, fewer complications, mean fewer headaches for board designers and us.

We have been asking for 3 IDF's if Serial ATA would be a competitor of SCSI interface. Until this IDF we couldn't get any clear answer. This IDF it became clear. In the Serial ATA II Spec they added smart command queuing capability. This has been the biggest gun of the SCSI Interface for years. Devices using SCSI protocol are able to queue and execute requests up to 255 without any assistance from the CPU or chipset. Plus SCSI devices have the able to disconnect from their host system bus to execute pending tasks. If you give ATA the same gun, price tag will win.

There is one more thing; Serial ATA NAS (Network Attached Storage) devices are ready for the market. Hot swap capability of Serial ATA and cheaper prices made it very attractive for the NAS and JBOD (Just a Bunch Of Disks) market. Instead of expensive Fiber Channel or SCSI devices, RAID 5 and hot spare enabled IDE drives are really attractive. One of the advantages of Serial ATA is, you don't need ID numbers. If you hook it up to the first connector it is Disk no. 1 and if you hook it up to second connector it is disk no. 2. So it is really easy to configure a Raid 5 configuration. There was a working sample on the showcase.

For DAS (Direct Attached Storage) Serial ATA has solutions too. NAS solutions include CPU, Memory and a kind of OS. DAS is just drives. If you simply want to add external disks to your network without any CPU "iSCSI" solutions are waiting on the corner but Serial ATA is ready with Serial ATA Hubs. You can connect disk boxes directly to your system by Serial ATA Hubs. If you want more disk space you may add another simple and inexpensive disk box.

Serial ATA has made RAID on motherboard solutions easier too. This is important for server motherboard market. Xscale based Intel IOP321 solution looks like to serve this need.

If we sum up these solutions, Serial ATA looks very promising and it may wipe up the more expensive SCSI solutions. Fiber Channel for Enterprise needs will stay and take over some of the SCSI market. But Serial ATA will steal most of that market share. I added a graph from Dataquest. It is a forecast but it looks logical.

I wanted to add some Acronyms for our geek dictionary.


  • DAS. Direct Attached Storage
  • NAS. Network Attached Storage
  • ROMB. RAID on the Mother Board
  • SAN. Storage Area Network
  • SATA. Serial AT Attachment


  1. Technology: A Look 2 to 5 Years in the Future
  2. 3GIO: A PCI Killer
  3. BBUL (Bumpless Build-Up Layer) PACKAGING
  5. E7500 CHIPSET
  6. Serial ATA