So what is it?
Initially SATA (or Serial ATA) was designed as an internal or inside-the-box interface technology, bringing improved performance and new features to internal PC or consumer storage. With a faster interface and improved connectivity. Ingenious tech heads realised that this connectivity could be used in a similar manner to USB and Firewire (IEEE 1394) interfaces as an external connectivity, and could possibly be a budget alternative to SCSI for high-end storage.
They called the new external version eSATA, with up to 2m cable lengths and the opportunity for multiple connections to an external eSATA array. This would allow users to take advantage of the benefits the SATA interface without the space limitations of an internal only connectivity.
eSATA is now registered as an external standard, with specifically defined cables, connectors, and signal requirements published as a standard in mid-2004. eSATA provides more performance than existing solutions and is hot pluggable (units can be swapped easily without machine shutdown).
Port multiplication allows a single eSATA controller to control multiple drives, so large arrays of disks can be easily controlled from a single workstation.
Why choose eSATA?
For external connectivity of storage you have really only four choices:
USB 2.0/USB 1.0
Not designed as a large data transfer connectivity the USB 2.0 spec was tweaked to allow faster throughput but the underlying protocol used for data transfer is not as fast as its theoretical maximum. Good for an end user backing up - not good for streaming FS video however. USB 2.0 hard drives are cheap and somewhat reliable - bear in mind though USB was invented for keyboards, mice and printers not 44Mb/s data transfer! One of the reasons for this is the overhead from the conversion of ATA (the internal drive used) to the external interface.
Firewire was designed as a digital storage interface, designed from the ground up with the purpose of providing a great way to get data into your computer fast. Developed in part by Apple and Sony, Firewire is more reliable and provides better speed than USB 2.0 (even though its theoretical maximum transfer rate is less) for moving data around - however for full uncompressed video it can lag. One of the reasons for this again is the overhead from the conversion of ATA (the internal drive used) to the external interface.
SCSI - Small Computer Systems Interface
One of the earliest connectivities for storage SCSI has evolved as time has gone on, it still today provides an exceptional data transfer rate but at an enormous cost. Typically SCSI drives cost around 4 -5 times as much as SATA or IDE drives (used in Firewire and USB drives) and require an expensive PCI solution for the host adapter.
eSATA devices do not have such performance overheads as FireWire and USB, since the drives are running the same protocol as the card so no translation is required. This means that eSATA has a theoretical transfer rate of 1.5Gb/s (SATA I) or 3.0Gb/s (SATA II) - compared to Firewire (400Mb/s) and USB 2.0 (480Mb/s).
This means that data can be pushed and pulled more quickly and easily with incredible sustained speeds.
eSATA is becoming the external storage solution default for many video and audio specialists who require high transfer speeds but don't want to pay for SCSI.
eSATA enclosures use simple SATA internal drives to allow an almost infinite amount of additional storage. Enclosures such as the Fusion from Sonnet allow up to 5 drives to be connected to your machine in one convenient enclosure, and controlled from a single eSATA controller - a 4 port controller card can therefore control up to 20 drives! It is possible (with the right number of eSATA PCI cards and enclosures) to add a huge amount of storage for a fraction of the price of SCSI.
Using MacOS 10's RAID facility, you can easily create large, fast access storage; with SATA pricing video and audio professionals can now have performance on a budget.
eSATA gives you performance to burn! You'll get great performance from individual drives, but grouping up to eight Serial ATA hard drives in a RAID 0 (striped) array reveals the true prowess of this connectivity - exceptional speed. Astonishing sustained read/write performance numbers in excess of 545 MB/s are easily possible of the shelf - that's more than enough to capture and process uncompressed 10-bit High Definition video!
What hardware/software do I need to use it?
At MacUpgrades we supply a host of eSATA adapters, cables, enclosures and drives from industry leaders such as Sonnet Technologies and Hitachi.
eSATA does not come as standard on any Mac at the time of writing, so to take advantage of this new protocol you will need to fit an eSATA host controller into a PCI/PCI-X, PCI Express or ExpressCard slot. This means that at present only the PowerMac, Mac Pro and MacBook Pro ranges of Macs can use eSATA devices.
Click here for our eSATA host controllers, enclosures, drives and cables.
Mac eSATA system requirements
- MacOS 10.2 or later
- G3 Blue and white or later with free PCI/PCI-X/PCI-Express socket.