As we have already mentioned several times in our reviews, IDE RAID controllers are getting more and more popular. In the first place it has to de with the fact that more and more users appear unsatisfied with the performance provided by IDE HDDs or their reliability (or even both simultaneously).

Recently the mainboard manufacturers have been working on two versions of their mainboards in most cases: one without the integrated RAID controller and one with it. And depending on what the market wants they produce this or that models in mass quantities. However, the today's IDE RAID controllers have a very limited features set. Usually they can implement very few RAID levels: RAID 0 (striping), RAID 1 (mirroring) and any of their possible combinations. In fact, an ordinary user may hardly need anything else. We dare state with a pretty great probability that the majority of home RAID systems are made of two hard disk drives. However, with only two HDDs at our disposal we could create an array, which would either provide an increase in the disk subsystem performance (RAID 0), or ensure higher reliability and protection for the stored data (RAID 1). In order to combine high performance with high reliability we will need two more HDDs, which far not every user can afford. A different thing is the low-cost servers, which also require higher speed and reliability, but do not care that much about the pricing issue. It is exactly the place for RAID 01 and RAID 10 to be used.

If you are unfamiliar with the RAID terminology and want to know a bit more about the differences between the RAID levels, please see our ATA/100 RAID Controllers Roundup for more information.

01 and 10 RAID arrays provide both: high performance and reliability, however, not forever. If any of the 4 HDDs breaks down, RAID 01 will degrade into RAID 1 and RAID 10 - into RAID 0. In other words, the system will keep working but will either slow down considerably or no longer guarantee the data on the drives is as safe and sound as it used to be. Of course, if the server is located not too far away from the operator, then he will be able to eliminate the problem pretty fast (in case he has a spare HDD at hand analogous to those used in the array, of course). And if the server is located quite a while away and the status-quo needs to be restored as soon as possible? In case of a SCSI controller, you can have one more spare hard disk drive in the PC, which simply isn't included into the array (it is called "hot-spare"). Just the same way the drivers usually have a spare wheel in their car trunk :-)

In case the problem is encountered by one of the array members, the controller can disable the damaged HDD and connect the hot-spare one instead, which will allow restoring the array as it was. This way things really do happen in case of the "right" SCSI controllers.

But what about the ordinary IDE RAID controllers? In fact, in case of RAID 01 array by a controller like Promise FastTrak or AMI HyperDisk, or any other one of the kind, all the IDE ports appear occupied. Where should we connect a spare hard drive then? Unfortunately, the simplest IDE RAID controllers do not allow adding a hot-spare HDD in case of RAID 01 or RAID 10 arrays. However, the today's market offers some more modern solutions, which let you forget about this problem. First of all, there is promise SuperTrak capable of working with 6 HDDs simultaneously (4 of them can be united into an array and the other two appointed to be hot-spare ones). Secondly, there are some controllers, which support not only RAID 0, 1, 0+1, but also RAID 5 (see this article for details on RAID 5).

Well, this article is devoted to a comparative testing of three IDE RAID controllers, which can boast a bit more than just RAID 0, 1 and 0+1. They are 3ware Escalade 6400, Adaptec AAA-UDMA and Promise SuperTrak100. From the very beginning we would like to draw your attention to the fact that we do not intend this article to be regarded as a complete investigation, because even after a month's work we didn't manage to check all the modes and combinations of parameters. However, we did our best to give you a really good idea of what these controllers are capable of and where they can be successfully used.

Closer Look

3ware Escalade 6400

At first, let's take a closer look at the package:

The box is quite big, we should say. However, the card is also not a small one. It is a full-size card with the built-in fastening handle. See the black square handle on the right side? In good cases it fits into a special hole to prevent the card from sagging.

The card looks very simple: you can notice only three large chips on the PCB. The main chip is responsible for the data transfer via PCI bus and manages the functioning of the entire device, while the other two are working with two IDE channels each providing contact with the HDDs in the array. Having removed beautiful stickers, we found out the following:

DiskSwitch

AccelerATA

These were the chips by a well-known Xilinx Company. They are also known as PLIC (Programmable Logic Integrated Circuits), i.e. the chips with programmable logic. These chips consist of some simple primary gates, which can be combined differently (just like the LEGO game) to create any kind of architecture. There are only two major restrictions: the number of gates used and the working frequency of the end chip.

The main advantage for the users here is the opportunity to correct or improve the device architecture composed of the chips like that via software. Which we actually had to do in our case, of course. The controller we got hold of, was unable to create RAID 5. To eliminate this drawback we downloaded new firmware for this controller from 3ware web-site (the set included an updated version for DiskSwitch as well as for AccelerATA) and reflashed it into the controller. The whole thing took no more than three minutes and hardly differed from the regular BIOS reflashing. Although if the power got suddenly switched off when the process was in full swing, then… god knows what could have happened.

Besides, the card is also equipped with the memory chips and 4 different IDE connectors. The connectors are located very inconveniently, so that the cables create a great mess inside the PC case.

Well, enough for visual inspection, let's pass over to the main specifications of 3ware Escalade 6400:

In this controller 3ware implemented two interesting technologies: StorSwitch and TwinStor.

3ware's patented StorSwitch architecture applies the principles of switched networking to servers, workstations and storage subsystems. The StorSwitch architecture employs a packet-switching design to give each disk a dedicated data channel and full drive bandwidth to the host PCI bus through a high-speed non-blocking switch fabric.

TwinStor technology is used in case of Mirror arrays and serves to improve fault tolerance and performance. In case of every new request the controller works with two mirrored drives simultaneously, thus increasing the read rate to its maximum.

Adaptec AAA-UDMA

Adaptec Company, which is very well-known due to its high-quality SCSI controllers also decided to put in a word in the rapidly developing IDE RAID controller market. And as we actually expected from a serious company like Adaptec, they launched not a Simple RAID 0, 1 controller, but a much more complex model called Adaptec AAA-UDMA.

The controller is shipped in a nicely looking box, and according to the package contents we concluded that Adaptec regards its newcomer as a really serious product: the manual in 4 European languages, the drivers for different operation systems, a CD-disk with Adaptec CI/O Management software, and each IDE cable packed into a separate plastic bag. This made a really good impression, guys :-)

Just look at the controller card. Unlike the one from 3ware, which we have just introduced to you, there is hardly any room left for at least a small chip on it. And mostly the chips are not that simple…

The chip responsible for the bus interface was made by Intel, while the IDE channels are again operated by a programmable chip. In fact, the use of chips like that is quite justified. You know that Adaptec has a huge experience working with SCSI controllers. And who may prevent the guys from integrating a SCSI-to-IDE Bridge chip into their SCSI controller? As far as we understood so far, Adaptec did exactly the thing.

AIC-7890 stands for high-level SCSI protocol, and AIC -7815G (the so called RAID co-processor) is busy working with the cache and fulfilling XOR-operations in RAID 5.

The cache represents a removable EDO DIMM module.

The controller is shipped with a 2MB module (as default), however it supports up to 64MB modules.

As for the interesting features typical of this controller we would like to mention the fact that the array should be created and managed not from the controller BIOS but with the help of a special Adaptec ARRAYCONFIG UDMA program, which starts after booting from a floppy disk.

Promise SuperTrak100

Promise SuperTrak100 controller card is shipped in a traditional orange box:

As you can see, we have all the accompanying stuff lying in front of the box here. The package is pretty traditional: user's manual, diskettes and CD-disks with software. The only missing thing on this picture is the cables. We didn't put them there on purpose. If we did it, you would never see anything else, because there are six cables in the package. Not four, but six, since this controller can work with six HDDs at a time. On the next photo you can see all 6 IDE connectors:

The controller is equipped with three promise PDC20265 chips.

You should be very familiar with these chips already because they are integrated onto a great lot of different mainboards and are also used on Promise Ultra100 UDMA100 IDE card.

The operation of all chips on this controller card is managed by Intel i960 (RD66):

Cache memory in this case is designed as a removable DIMM FPM module.

The controller chip woks at 66MHz and is quite happy with the performance provided by a regular PC66 FPM module.

As default the controller goes with a 16MB cache memory module made of the chips produced by some Tonicom Company, which we haven't heard of before, actually. Officially controller supports up to 128MB memory modules, so there is room for improvement.

Unlike the previously considered controller cards, this one is equipped with the built-in indicators:

When the controller is working, the red lights keep blinking very nicely. However, unfortunately you can enjoy this blinking only if the PC case is open or if you turn it with the rear side to the font.

And here you can see all the cables connected to the card. Now you understand why we didn't want them on the general picture: there is a real lot of them:

The specs of Promise SuperTrak100 look as follows:

Testbed

Some time ago we assembled a special testbed for HDDs testing and today we are happy to introduce it to you:

When we decided on a PC case for it we were guided mostly by the following two reasons. Firstly, the case had to possess removable HDD holders and secondly, it had to provide easy access to all the insides. SuperMicro 601 was exactly the case that met all our requirements that's why we chose it. Although we didn't leave it as it was but still introduced a couple of changes. First of all we replaced the power supply unit, because the one available had too few power connectors, which were not enough for all our hard disk drives:

We preferred PowerMaster unit with 7 power supply connectors.

Then we had to add a bit more coolers into the system. One cooler was fastened from the inside to the rear panel of the PC case. Then two more coolers were put onto each of the two HDD holders. Unfortunately, only one holder of the two was equipped with a special mechanism for proper cooler fastening. However, we didn't give in and simply resorted to the help of thermal glue. To stick the cooler to the second HDD holder like this:

After all these manipulations we assembled the following test system:

• Intel Coppermine 600MHz CPU;
• ASUS CUBX-E mainboard 1007A BIOS;
• 2 x 128MB PC133 SDRAM by Hyundai;
• WD Caviar 200BB HDD;
• 6 x IBM DTLA 307015 HDD;
• Matrox Millennium 4MB graphics card;
• Windows 2000 Pro.

Since all the controllers support only one hard disk drive per channel we set all drives as Master-units. Here we would like to point out that all the controller cards were provided with their own UDMA cables, which are the only suitable ones for them. You can't use a standard cable with any controller. Moreover, the cables taken from one controller of the three tested, do not fit for the other one. That is why there should be no problems with the cables.

We ran all the tests under Win2000 Professional. We used FAT32 and NTFS file systems to format each of the hard disk drives as one logical drive of the maximum size with the default cluster. All the tests were run 4 times and then the average results were taken for the diagrams. The HDDs didn't rest for cooling down between the tests.

Here are the benchmarks used:

• WinBench 99 1.2
• HDTach 2.61
• Drive 1.0
• IOMeter 1999.10.20

For the controller cards the following driver versions were taken:

• 3ware Escalade 6400: driver version 1.09.00.015;
• Adaptec AAA-UDMA: driver version 4.40.09;
• Promise SuperTrak100: driver version 1.10 (build 22).