IDE RAID Comparison

by Matthew Witheiler on June 18, 2001 4:31 AM EST

Conclusion

There is little question that RAID is making its way into the world of home computers. Once reserved only for servers and high end workstations, the increasing power of the CPU and the decreasing price of hard drives both made the proliferation of RAID possible. There is, however, quite a bit of misunderstanding regarding RAID and its features.

The pages above should have helped straighten out the technology and principles behind RAID and, at the same time, given the reader a good idea of what kind of performance to expect out of a RAID array. Software RAID chips like the ones tested here are found integrated on a variety of motherboards. In addition, PCI software RAID cards have been falling in price for some time now and can be purchased for a rather good price.

There is no question that a software RAID 0 IDE array will make your computer run faster, as the Content Creation Winstone 2001 scores clearly showed. Performance gains on the order of 13% are not negligible Just be sure that your software RAID chip is set to use its optimal stripe size, which we found in previous sections. The difference between a good stripe size for your card and a bad one can mean the difference between being faster than a single IDE drive or being slower than it.

Don't let the speed increase that comes with a RAID 0 array fool you into thinking that you can use older drives and get the same performance. The fact of the matter is that unless your IDE drives in the array are fast, the array simply won't perform well. The same can be said with mixing fast drives and slow drives: the performance of the array will go down.

For those not interested in speed, there are two solutions for you: RAID 1 and RAID 5. We found that mirroring, or RAID 1, provides a good way to maintain data integrity without a major loss of speed. Performance of our RAID 1 arrays were nearly identical to the performance of the single IDE drive we tested.

RAID 5 solutions should be reserved only for those who need it. We saw that a RAID 5 array can really decrease the performance of a set of drives, enough so that no home user will likely opt for this solution. RAID 5 is good in situations where data integrity is extremely important as well as in situations where the CPU is constantly under extreme load and disk access occurs on a regular basis. In these situations, the cons of RAID 5 are offset by the advantages of a very reliable data structure as well as very low CPU usage.

Of the three software RAID cards tested, the Iwill SIDE RAID100 and its Highpoint HPT370A chip provided the best RAID 0 performance, offering a bit more speed than the competing chips. On the RAID 1 side, it was the MegaRAID 100 and the AMI MG80649 chip that resulted in the best array performance. Finally, when it came to hardware RAID 5, both cards performed similarly in real-world tests. We would recommend the Promise SuperTrak100 over the Adaptec AAA-UDMA for a few reasons, including the larger standard cache size and extra drive capabilities.

Complete Performance: RAID 1
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  • kburrows - Thursday, December 4, 2003 - link

    Have you run any tests on any onboard RAID solutions for RAID 0 & 1? I would love to see the results posted for the new SATA RAID on the Intel 875 boards.
  • Anonymous User - Sunday, August 17, 2003 - link

    In adressing the performance of an raid array with different stripe sizes, you miss an important factor, namely the accestime of an disk. This wait time has two main couses. First the head positioning and second the rotational latency (the heads track the right trace, but position where the read start has not passed under the head). You may have to wait from 0 to (in the worst case) a full cycle.
    Since the disks move independently You can calculate that the average latency to get an small file is minimal when the stripe size is about an full cycle of an disk in the array (aprox. 250kB today). All other factors I do know do not reduce this. (controller overhead, transport,...)
    So I think that today a minimum stripe size of 256kB should be used.

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