Fast and Inexpensive - Promise's FastTrak66 IDE RAID-Controller

Introduction

Promise, a company that is known for their dedication to IDE hard drive controllers since the days of 'EIDE' or 'enhanced IDE' had a pretty hard time when chipset makers as Intel or VIA started to integrate IDE-controllers into their chipsets. People simply didn't need an extra hard drive controller unless they wanted to use SCSI. Each time when a new IDE-specification had been released however, Promise was able to supply a product that would upgrade current systems to the latest IDE-standards. This was the case with 'ATA33', a IDE controller spec that offers up to 33 MB/s data transfer rate between the hard drive and the system, which was first introduced with Intel's good old 430TX-chipset in 1997. At that time, people who owned motherboards with 430FX/HX/VX chipsets (supporting only modes up to 22 MB/s) could upgrade their system with a Promise Ultra33 card, enabling ATA33 mode. Today, Intel's 8xx and VIA's latest chipsets support 'ATA66'. This spec requires new cables between the motherboard and the hard drives, and it's offering up to 66 MB/s data transfer rate. Motherboards with Intel's BX-chipset don't support ATA66 and so Promise could sell their 'Ultra66'-controller to owners of systems with those motherboards.

Now there's one important thing to remember though. Even the fastest IDE drives today can only supply data rates of 30 MB/s when reading the data directly from the disk. Only data that happens to reside in the dedicated read/write cache on the hard drive can be transferred at a higher speed. The same is valid for writes. Data can be transferred to the drive pretty fast, until the cache is full. Then the write speed rate is again limited by the physical abilities of the hard drive, which today is in the range of 20-30 MB/s. Thus you can hardly ever see any improvement when you switch from ATA33 to ATA66. Especially hard drives with small caches can take only little advantage of ATA66. This does of course not mean that the physical read/write rates of IDE hard drives won't skip the 33 MB/s limitation of ATA33 very soon, so ATA66 does make perfect sense as long as it doesn't come at a too high premium.

Besides the normal IDE-controller cards, Promise is also offering RAID-cards for IDE drives. This article will have a close look at Promise's RAID-controller card with ATA66-support, the 'FastTrak66'.

RAID

When the average computer user hears the term 'RAID', he either doesn't have a clue what it is altogether, or he might have heard about it in combination with large servers and security issues. Even normal workstations are rarely using RAID, so you might wonder why I am going on about it here.

I also used to put 'RAID' into the world of high-end servers and SCSI-systems, so that it sounded pretty weird to me, when I heard of IDE-RAID for the first time sometime in 1998. However, I finally had to find out that I had been wrong. Once RAID is affordable, it also makes sense in a lot of average systems.

The definition or 'invention' of RAID goes back some 12 years. In a 1988 publication, A Case for Redundant Arrays of Inexpensive Disks (RAID) , three University of California-Berkeley researchers (David Patterson, Randy Katz, and Garth Gibson) proposed guidelines for these arrays. The idea was to use 'inexpensive' hard drives to create a large, fast and reliable/secure mean of data storage. If you want to learn more about RAID, I would suggest to read the excellent white paper 'RAID Technology ' from Dell's website. I will only concentrate on the RAID levels offered by Promise's FastTrak66 controller, to keep this article at a reasonable length.