Promise FastTrak S150 TX4 Raid Controller 21st July 2003

Feedback from our recent review of the Promise SX4000 RAID Controller card indicates that HDTach graphs are a little too confusing for most our readers who would like to see simpler graphs. We still believe HDTach provides the most comprehensive analysis of hard drives across their entire surface area but instead of detailed graphs we will now be providing sustained read and write scores (ignoring the effects of burst read and writes as well as random read/writes - we've never encountered a hard drive fragmented badly enough to come close to random read/write figures).

The card also has a lot of exciting features. Here's what you get.

Included are four S-ATA leads, a parallel lead and a two S-ATA power adaptors. As usual promise include everything needed except for the drives themselves. 

The card itself is quite small and has four Serial channels. The low number of surface components indicates a highly integrated design. Although four channels are present the controller will happily work with only one drive, making it a useful upgrade to S-ATA that allows for future headroom (just add more drives).

The four connectors are evenly spaced and give the impression of sparseness on the card. Comparing this to the TX4000 which is the parallel equivalent tells us that S-ATA is definitely the way to go to reduce clutter inside a PC case.

Here's a screen showing the configuration of the test system:

It should be noted that for testing purposes we managed to obtain 4 Maxtor S-ATA 250GB drives with 8MB cache and 7200rpm. These drives are aimed at the enterprise storage market and come with a 5-year warranty indicating the confidence Maxtor have in this product. For parallel drives we used 2 Maxtor ATA-133 160GB drives with 8MB cache and 7200rpm to match the specifications of the S-ATA drives as closely as possible. In practice, those purchasing this product may not be able to match as closely as this (or may not desire to if they want to purchase the fastest S-ATA drive possible) so readers will need to remember the basics of using RAID on non-matched drives. These basic rules stipulate that performance is limited to N times the speed of the slowest drive and total size is limited to N times the capacity of the smallest drive where N is the number of drives in the array. In practice these are theoretical maximums that may be limited by other factors.

Here are the 4 drives we managed to pull together showing the ease of connectivity to the card:

There's hardly any clutter of cables even with 4 drives.

Serial cables plug easily and securely into the card without blocking airflow.

The above picture clearly illustrates how little space is taken up by the connectors of S-ATA drives. The drives used are all Maxtor 250GB S-ATA 7200rpm 8MB cache ones (that's a Terra-byte of storage which may seem outrageous even by today's standards but then we remember Bill Gate's famous speech telling us we will never need more than 640K memory in our PCs and must remind ourselves that no one knows what future requirements will be). The drives with the black data connectors are plugged into the Promise controller and the ones with the red connectors are plugged into the onboard RAID controller.

For comparison we will use a HighPoint HPT372 and a Promise TX4000

Each test will be conducted at stripe sizes of 16K, 32K and 64K to see which is most efficient.

RAID1 (mirroring) testing will be conducted at default stripe size as we are not given the option of changing this parameter.

RAID0

Let's start with some HDTach graphs to show performance across the entire 500GB of each array.

The top graph is the S150 TX4, the middle one is a S150 TX2 and the bottom one a Silicon Image controller thrown in for comparison. All graphs show the results of RAID0 using two S-ATA drives. A full size graph can be obtained by clicking on them. OK, no more complicated graphs from here on.

The S150 TX4 leads in all configurations, hitting the PCI ceiling with only 2 drives.

The situation remains the same with the cards pressing the PCI ceiling more.

64K seems to be optimal and the S150 TX4 is well in front.

RAID1

This involves using half the drives to mirror the other half, duplicating all write operations but ensuring data integrity. If one of the drives fails it can be reconstructed from the mirroring drive.

As expected performance is lower but those looking at this option want data integrity first and performance second. In any case the results are not too bad. While write performances are roughly equal in most cases the read performance of using four S-ATA drive for mirroring is vastly superior to the other products.

Tips for Improving Performance

Some thought needs to go into planning a RAID array. Small stripe sizes favor large numbers of files being transferred while large sizes favor activities such as video editing etc. Generally a 16K stripe size works best for everyday use. To get the best performance it is necessary to format the Array using a cluster size that is a whole multiple of the stripe size. For example if the stripe size is 16K then it is best to use 16K or 32K as the cluster size. The reason for this is that Windows sends/requests data in blocks that are made up of the cluster size. The RAID controller allocates these to the first free drive in the array in sizes of the stripe size. So a 32K cluster would be split into 2 16K blocks and sent to 2 disks and this would be optimal for 2 or 4 disk Arrays. 4K clusters would have to be accumulated until 16K was ready and then sent to the first disk while the other(s) were waiting for data. In practice this is not too bad as the cache on modern drives compensates for this but the greater the number of drives in an array the greater the need to take such factors into consideration.

Conclusion

The Promise FastTrak S150 TX4 is the highest performing RAID Controller so far from Promise with a small footprint and easy installation it is an ideal way of jumping on the S-ATA bandwagon. Even if your motherboard has S-ATA there are no onboard RAID controllers that support 4 drives. In fact the best previous solution was Intel's ICH5R Southbridge which bypassed the PCI limitation but it does not support a 4-disk array. S-ATA is the way to go and the Promise S150 TX4 is the best 4-drive solution so far.

We give the Promise S150 TX2 Plus our Gold Award.

We would like to thank Promise Technology Inc. for the review sample.

All trademarks are the property of their respective owners.