Serial ATA (SATA) is a point to point connection. Each SATA port can connect to one and only one drive. The whole concept of master/slave kind of goes out the window. Most SATA controllers will maintain software compatibility by emulating the ATA task file interface. The normal 4 drives can be supported without any special drivers, even though all the drives will be considered masters.
Yes, the current media rates are much slower that the interface rates. This is a much better situation than the other way around. Three years from now, when the drives are even faster, you'll be glad that the interface is that fast.
Internal buffer (cache) sizes in the drives are also getting larger. While this does not help sustained performance, you can really get a nice speed improvement if the data you want is in the cache on the drive.
There are several new things happening in the SCSI world. U320 is the latest available option in the parallel SCSI world, providing a theoretical 320MB/s on the SCSI bus. Adapters and drives are starting to become available now.
Recently, T10, the SCSI standards organization, has accepted the Serial Attached SCSI protocol into its fold. Like SATA, it is a serial interface to disks. It offers several advantages over SATA, including:
Support for the SCSI protocol
Support for tagged queueing, allowing the drive to multitask. The standard ATA and SATA protocols do not support this yet.
A single port can connect to multiple drives through an expander (similar to a switch). Currently, SATA is a strict point to point connection.
Multiple adapters can talk to the same drives.
Backward compatible support for SATA drives using a tunneled protocol that even allows multiple adapters to talk to the same SATA drive.
Initial speeds of 1.5 Gb/s and 3Gb/s per port, compared to SATA's 1.5Gb/s per port
Expect Serial Attached SCSI to be targeted at the server market. SATA will be targeted more at the desktop and low end servers where performance and reliability aren't as critical, but cost is.
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Serial ATA (SATA) is a point to point connection. Each SATA port can connect to one and only one drive. The whole concept of master/slave kind of goes out the window. Most SATA controllers will maintain software compatibility by emulating the ATA task file interface. The normal 4 drives can be supported without any special drivers, even though all the drives will be considered masters.
Yes, the current media rates are much slower that the interface rates. This is a much better situation than the other way around. Three years from now, when the drives are even faster, you'll be glad that the interface is that fast.
Internal buffer (cache) sizes in the drives are also getting larger. While this does not help sustained performance, you can really get a nice speed improvement if the data you want is in the cache on the drive.
- Support for the SCSI protocol
- Support for tagged queueing, allowing the drive to multitask. The standard ATA and SATA protocols do not support this yet.
- A single port can connect to multiple drives through an expander (similar to a switch). Currently, SATA is a strict point to point connection.
- Multiple adapters can talk to the same drives.
- Backward compatible support for SATA drives using a tunneled protocol that even allows multiple adapters to talk to the same SATA drive.
- Initial speeds of 1.5 Gb/s and 3Gb/s per port, compared to SATA's 1.5Gb/s per port
Expect Serial Attached SCSI to be targeted at the server market. SATA will be targeted more at the desktop and low end servers where performance and reliability aren't as critical, but cost is.