SCSI Lives! Quantum Atlas 10K II — THG.RU

SCSI Lives! Quantum’s Atlas 10K II Hard Drive

Only a few years ago, SCSI drives used to be far superior to IDE models. People who needed high data bandwidth, low access times and large capacities had to pay the SCSI-premium, because IDE-drives of were significantly slower and smaller.

Today the picture has changed. The advances in the IDE-sector have been so vast that nowadays the largest hard drive is an IDE-model and the fastest IDE-drives are only marginally slower than the fastest SCSI-drives.

It comes to no surprise that SCSI has finally disappeared from the home and office segment. IDE hard drives are offering excellent performance, large capacities at a very reasonalbe price. SCSI is a lot more expensive and complicated to set up, while hardly offering any benefit to the home or office user. Quality IDE or ATAPI components can easily live up to his expectations. IBM and Maxtor are shipping fast and huge UltraATA/100 drives, Plextor provides an excellent 12speed CD writer with buffer-underrun protection system, and IWill, Promise and others supply IDE RAID-controllers.

Still SCSI has still got its advantages over IDE. Large RAIDs are one example. Then you can connect 7 or 14 devices to the SCSI-adapter, like CDRWs, Scanners, of course hard drives and more. However, due to SCSI’s price premium most people will prefer USB-connections for scanners, IDE-RAIDs and even IDE-CDRWs today.

Times for SCSI are hard. Most hard drive manufacturers are focussing more and more on IDE drive development. It has become difficult to develop SCSI components that are significanty better than IDE products, especially if the developer wants to meet reasonable price points.

At this point we are seeing a clear split. SCSI has died out in home and office computers. However, it is still the one and only high-end storage platform. It offers best flexibility due to vast drive arrays, terabyte capacities, cache controllers and hot plugging capabilities. This cannot be provided by any IDE system … yet. SCSI is still able to provide a lot more than IDE — at astronomical prices.

Ultra160-SCSI

The latest SCSI-revision is able to provide up to 160 MB/s. Some people may wonder how this is supposed to work with a normal PCI-card, which has a bandwidth limitation of 133 MB/s. The answer is simple. Most Ultra160 cards are only available as 64 Bit PCI cards. A few Ultra160 cards are available as 32 Bit models.

Luckily, every 64 Bit card can also be used in 32 Bit PCI slots — as long as there is no component in the card’s way.

You may wonder what’s the use of a bandwidth of 160 MB/s when even the fastest SCSI hard drives can only supply a data stream of up to 40 MB/s. You’ve got to remember that SCSI is a bus system with which you can daisy-chain 7 or 14 devices. Those devices are all sharing the SCSI-bandwidth. Therefore 160 MB/s can easily be used up with a RAID that consists of four high-end hard drives. Adding more hard drives to this RAID would already require a higher bandwidth.

The performance of 160 MB/s is be achieved using a technology called ‘Double Transition Clocking’. It’s the same basic idea which is used with AGP2x, double data rate memory or the Athlon’s double-pumped system bus. Data is transferred at both the rising and the falling edge of a bus clock cycle, thus doubling the transfer performance without increasing the bus clock.

There are some other innovations that Ultra160 takes advantage of, which are making this standard faster and more secure than all prior versions. The explanation of those would go too far, so I decided to skip this part for the time being.

If you want to know more, please check at IBM’s website.

Similar information can also be found on Adaptec’s website.

SCSI vs. IDE

While IDE adapters can be found on every motherboard for many years, you will have to specially purchase a SCSI adapter in most cases. A few motherboards are available with integrated SCSI-chip however. Those fully featured motherboards are clearly cheaper than a standard motherboard plus a PCI SCSI adapter card, but you can easily exchange the card if you want to upgrade to a faster or better featured one (e.g. multi-channel cards, RAID adapters etc).

IDE was born in 1984 in order to introduce a cheap interface for hard disk drives. IDE means Integrated Disk Electronic, which explains the basic idea: The controller chip is on the disk drive, not on the adapter (like SCSI). First IDE drive generations had been rather expensive, but mass production made the prices drop far below the costs for SCSI drives. IDE standards are updated on a regular basis, starting with programmed-I/O modes (PIO) 1, 2, 3 and 4, UDMA33, UDMA66 and today UltraATA/100 is the state-of-the-art standard for up to 100 MB/s of bandwidth. It is still downward-compatible; thus you can use every old IDE drive as well.

In order to keep up compatibility, the principle has never been changed. Two drives can be operated from one IDE channel. One is the ‘master’ drive, the other will be ‘slave’. With the introduction of the ATAPI standard, CD-ROM drives could also be operated from IDE controllers. Therefore a second IDE channel became common, as attaching one hard drive and the CD-ROM would not have left any room for future upgrades.

The SCSI bus is both more complex and more flexible. Every device gets assigned a SCSI-ID number. It can either be set directly on the devices (using jumpers), or the host adapter assigns them. The most important advantage is the amount of supported drives: 8 devices can be in a SCSI chain, with one of the devices being the host adapter. Each end of the SCSI chain has to be ‘closed’ with a terminator to prevent signal reflexions.

All devices can also be operated externally. Some drives (e.g. Iomega Jaz) can be obtained as external SCSI versions. There are also special SCSI cases available where you can place hard drives, CD drives, streamers or other hardware. Also SCSI scanners are very popular due to the higher bus performance compared to USB or the parallel port.

Thanks to complex controller chips, SCSI is able to access all drives almost simultaneously, which is still not possible with IDE. Decent SCSI-adapters have its own processor and are able to do bus mastering, so that SCSI-bus tranfers don’t cost any significant CPU performance.

Drive Details

More Information can be found in the product datasheet.

Here you can see the Atlas 10K II (left) and a IBM DTLA drive. The SCSI drive has a height of 1.6″ whilst IBM’s DeskStar model has 1″.

This high-end model is the first hard drive I know that comes with a BGA chip.

Looking at the back side you can see the 68-pin connector and the black ribs which are meant to improve the heat dissipation.

Test Setup

SCSI-Adapter: Tekram DC-390U3D

The Tekram DC-390U3D is a 64 Bit dual-channel Ultra160-adapter. Both ports can also be used externally, making this controller an excellent choice for external multi-drive solutions. Tekram includes two cables as well as two active terminators and an adapter for external 8 Bit devices.

Benchmarks: Data Transfer Performance

You can clearly see the Quantum high-end drive breaking the barrier of 40 MB/s. I guess it’s interesting for many of you to see that the drive is as «slow» as the IDE models if you fill the drive completely. ‘At the end’ of the drive, only 20.5 MB/s are provided.

Benchmarks: Disk Access Time

Thanks to the high revolution speed of 10,000 rpm the Quantum Atlas 10K II is clearly faster than today’s 7,200 rpm drives.

Benchmarks: WinBench 99

Here is a little disappointment for everybody who thought that a super-fast hard drive will speed up all kind of applications. The WinMark test simulates the disk accesses which take place in the WinStone run (Business or Highend).

Disc Operating Noise

Usually I start the graphics at zero. In this case, I wanted the difference to look bigger due to the nature of the results. The Decibel-Scale is exponential which means that 10 dB(A) more is double the noise!

Due to the high rotation speed the Atlas 10K II is acustically always present with a high frequency whistle, disqualifying the drive for desktop use. The disk access noise is quite cracky.

Disc Operating Temperature

As expected the 10,000 rpm drive becomes clearly hotter than usual 7,200 rpm models. Thus I would clearly advise against running such a hard drive without a dedicated fan. We measured the temperature of 57 (C after one hour. I guess if it is properly installed in a computer case, the temperature will easily reach 70 degrees if you don’t cool the drive.

Overheating always means data loss and a reduction of the drive’s life span, so don’t forget to cool high-performance drives.

Conclusion

After several reviews of IDE hard drives, this article is the first review of a professional SCSI hard drive. At prices of $ 1000 and more (73.4 GB), those models are very expensive and not particularly suitable for home users.

The drive is made for workstations or servers and will mostly be found in stripe sets or other types of disk arrays. 8 MB cache memory are not provided by any of the two most important competitors: IBM’s Ultrastar 36LZX comes with 4 MB cache whilst Seagate’s Cheetah 73 series is available either with 4 or 16 (!) MB buffer.

The biggest advantage of a 10,000 rpm drive is not primarily the better transfer speed, but the clearly shorter access times. Those are of major importance for database or web servers, which might be the primary area where those kind of hard drives are used.

Even if money was not important I would never want to use such a hard drive in a desktop computer. Games do not require such fast hard drives. Applications like Adobe Premiere, Photoshop and others will of course benefit from the high performance drive, but both the access and the standby noise will stress you out.