
Enthusiasts have an unwritten rule: Western Digital's WD1500 Raptor is the perfect desktop hard drive for those with performance ambitions. But the rule is difficult to follow for folks with budget restrictions, since most of us cannot afford $200 for a hard drive that stores a mere 150 GB. Is the Raptor still the best choice? Pricing hasn't changed for months, and you can easily get a 400 GB hard drive for half the money. Hence I believe it's time for RAID arrays to challenge the Raptor - again.
Hardware connoisseurs are very familiar with the Raptor, because it is the only 3.5" desktop hard drive that spins at 10,000 RPM. Most desktop drives rotate at 7,200 RPM and only expensive server hard drives run faster. The first WD Raptor at 36 and 74 GB was introduced three years ago. One year ago, the Western Digital Raptor-X was introduced, offering more performance and an optional clear cover, allowing enthusiasts to look inside the drive.
Ever since Western Digital released the Raptor, it has beaten all other 3.5" Serial ATA hard drives in the desktop space, despite originally being designed for entry-level servers. Please check out our Interactive 3.5" Hard Drive Charts to see how your hard drive stands against the Raptor drives.
The spindle speed of 10,000 RPM provides two significant advantages over slower drives. First, data transfer rates increase noticeably. While its maximum sequential read performance is no longer unmatched, the minimum transfer speed remains far superior to that of any 7,200 RPM drive. On the other hand, 10,000 RPM drives exhibit shorter rotational latencies, which means that the drive has to wait less time for data to pass the read/write heads once they were positioned.
The clear disadvantage of WD's Raptor is its hefty price tag of $200 or more - be ready to fork out $230 in retail stores. Other drawbacks are higher (although certainly not annoying) operating noise, and noticeably higher heat dissipation due to rotational friction. Real enthusiasts, however, will easily accept these drawbacks in exchange for maximum storage subsystem performance.
Consider the cost per gigabyte ratio, and the Raptor doesn't look that great anymore. $200+ will buy you at least two 400 GB hard drives, and gets you close to the $275 for a Seagate Barracuda 7,200.10 at 750 GB. At the low end you can get two 160 GB 7,200 RPM drives for $50 each, which will give you twice the capacity of a single Raptor at half the cost. Eventually, even hardcore enthusiasts have to ask themselves whether it still makes sense to purchase a WD Raptor, or if a RAID 0 setup with two 7,200 RPM drives is the better choice.
Though a RAID 0 array doesn't reduce access time, it does effectively double sequential transfer rates, because data is striped across both drives. The downside is an increased risk of a data loss, because one of the two hard drives failing will cause the whole array to be lost (although RAID recovery is possible). Many on-board storage controllers in upper mainstream and enthusiast class motherboards support RAID modes, which should make it very easy to set it up.
| Performance | Capacity | Data Safety | Cost | |
|---|---|---|---|---|
| Single Drive (7,200 RPM) | Good | Sufficient to Excellent | sufficient* | Low to high: $ 50 to $ 300 |
| 150 GB WD Raptor (10,000 RPM) | Excellent | Sufficient | sufficient* | High: $ 200+ |
| 2x 160 GB (7,200 RPM) | Very good to Excellent | Good to excellent | insufficient* | Low to high: $ 50+ per drive |
| 2x 150 GB WD Raptor (10,000 RPM) | Excellent | Good | insufficient* | High to very high: $ 200+ per drive |
* You should be well aware that every hard drive will die sooner or later; the technology is largely based on mechanical components, which have a limited life span. Manufacturers rate drive life span using MTBF numbers (Mean Time Between Failures). If you set up a RAID 0 hard drive with two 7,200 RPM drives you have to live with a twofold increase of losing data, because the whole RAID 0 array dies if either drive fails. Be sure to make regular backups of your important data, and you should even create an image of your operating system.
You can get 40 to 80 GB hard drives for very little money, and if you don't have any requirements for storage capacity these drives suffice even today. However, we recommend spending at least $50 to $70, because you can easily get 120 to 200 GB in this price range. We've already seen 250 and 320 GB hard drives for less than $100 as well. Spending the money for a 10,000 RPM WD Raptor will give you between 800 GB and 1 TG storage capacity in the form of 7,200 RPM drives.
If you do not require that much storage capacity, you can opt for entry-level 7,200 RPM drives. Two WD1600AAJS drives by Western Digital cost $55 each, and they will give you 320 GB storage capacity if configured in RAID 0 model. Hence you end up spending half the money, and getting double the capacity. But where do we cross the line between saving at the wrong end and reasonable cost savings?
7,200 Or 10,000 RPM? RAID 0 Or Raptor?
We decided to send all possible drive configurations through our benchmark suite. There is the single WD Raptor WD1500ADFD, the single WD4000KD, the Raptor in a RAID 0 setup and the WD4000 in a RAID 0 setup. We decided to use the 400 GB WD 7,200 RPM drive, since two of these match the cost of a single Raptor. Let's see if the "budget RAID" fades facing the Raptor, or if it holds up.

The WD4000KD comes with 16 MB of cache and a Serial ATA/150 interface. The major differences compared to the 10,000 RPM WD Raptor are the drive's performance and capacity. The Raptor suffers heavy defeat in the cost per gigabyte category, as it is at least six times more expensive per gigabyte than the 400 GB WD4000KD. The benchmarks will show what the performance differences are like.
10,000 RPM WD1500ADFD Raptor

The Raptor is the undisputed champion in the desktop hard drive arena, but it also is the most expensive drive. The WD1500 Raptor only uses a Serial ATA/150 interface, which is still enough. If you have a look at our Interactive Hard Drive Charts you will notice that no other drive outperforms the Raptor, although more and more products run a 300 MB/s SATA interface. Clearly, SATA interface speed should not have an influence on your purchasing decision.

This setup resembles the ultimate challenge for the WD1500 Raptor. Will two WD4000KD drives in RAID 0 outperform the Raptor in every benchmark?
State-of-the-Art: 10,000 RPM RAID 0

Although this scenario is by far the most expensive - it requires two WD Raptor drives - it certainly is the most desirable as well. Two 10,000 RPM Raptors in a RAID 0 setup should blow everything else away easily.
RAID 0
Performance Expectations
In theory, RAID 0 promises to be an ideal performance array, as the sequential transfer performance multiplies almost linearly with the number of drives added to the array. Files are distributed block by block across all drives, which allows the RAID controller to write data onto all drives almost simultaneously. Transfer performance measurably and noticeably increases for almost all application scenarios, though access times cannot be shortened. In real life, access times usually suffer from a marginal increase in RAID 0 setups. This is no reason for worry, as we're talking about half a millisecond, which is nothing you will ever notice.
The storage controller may in fact become a bottleneck if you set up a RAID array with multiple drives. PCI devices max out at 133 MB/s, which even two hard drives reach easily today. Serial ATA controllers that are part of a motherboard chipset usually provide much stronger backbones and typically don't limit RAID performance.
We measured up to 350 MB/s using four 10,000 RPM WD Raptor drives and Intel's ICH7 or ICH8 chipset components. This is an excellent result, as it almost matches the added throughput of four single drives. At the same time, Nvidia's nForce 680 chipset somehow showed a 110 MB/s bottleneck, which we still couldn't overcome. It shows that not every integrated controller is suitable of hosting a high-performance RAID 0, despite technically supporting it.
We have to point out that RAID 0 does not really incorporate the key idea behind RAID, which stands for Redundant Arrays of Independent/Inexpensive Drives. Redundant refers to storing data at least twice, so the array will still hold an intact data set in case one hard drive of the array should die. RAID 1, for example, mirrors data on a second drive in real time, so if one of the drives fail, you'll only notice because your RAID controller tells you about it. RAID 5 is the more sophisticated, professional option. It works like a RAID 0, distributing data blocks across hard drives, but it includes a stripe set with parity data. Therefore, the net capacity of a RAID 5 equals the total capacity of all drives minus one drive. The parity data is not written onto a single drive (which would be a RAID 3), but rather is distributed across all drives to avoid creating a performance bottleneck when reading or writing parity data from a single drive. RAID 5 requires at least three hard drives.
Risks And Side Effects
RAID 0 is vulnerable to faulty hard drives, as one broken drive will kill the entire array. This is why chances of a hardware failure multiply with the number of RAID 0 drives: using three drives, you have three times the probability that your RAID partition may fail due to a broken hard drive. This is why RAID 0 is not an option for users who insist on a reliable system and cannot afford system downtime.
Even if you pick a powerful stand-alone RAID controller, you depend on this piece of hardware. Although two different products may support RAID 5, you never know whether or not the implementation is the same.
Performance & Safety: Intel Matrix RAID

Intel Matrix RAID: Use one set of hard drives to create various RAID arrays. Source: Intel.
If your RAID controller is smart enough, it may allow you to install two or more RAID arrays on a common set of hard drives. While every RAID controller supports multiple RAID arrays on different hard drives, the concept we're referring to is different. Intel's Southbridge components ICH7-R and ICH8-R are capable of supporting the Intel Matrix RAID feature.
A typical application would be two RAID arrays on two hard drives. The first third of both hard drives can be used to install a quick RAID 0 for your operating system, while the rest can hold a redundant RAID 1 for vital data. One faulty drive will kill your operating system and render your system useless, but the really important data still is available on the second drive thanks to the safe RAID 1. Smart users create a system image after completing their Windows installation, which can be stored on the secure RAID 1. This will help to restore the operating system in case of a hard drive failure.
Be aware that any RAID setup requires dedicated RAID drivers (e.g. Intel Matrix Storage Manager), which can be a problem if you have to boot a recovery system. Any recovery OS or recovery CD needs the right drivers to access or restore a broken RAID array. Before you rely on a RAID array, you should definitely practice handling the worst case.
Setup For Low Level Benchmarks
| System Hardware | |
|---|---|
| Processors | 2x Intel Xeon Processor (Nocona core)
3.6 GHz, FSB800, 1 MB L2 Cache |
| Platform | Asus NCL-DS (Socket 604)
Intel E7520 chipset, BIOS 1005 |
| RAM | Corsair CM72DD512AR-400 (DDR2-400 ECC, reg.)
2x 512 MB, CL3-3-3-10 timings |
| System Hard Drive | Western Digital Caviar WD1200JB
120 GB, 7,200 RPM, 8 MB cache, UltraATA/100 |
| Mass Storage Controller(s) | Intel 82801EB UltraATA/100 Controller (ICH5)
Silicon Image Sil3124, PCI-X |
| Network Controller | Broadcom BCM5721 On-Board Gigabit Ethernet NIC |
| Graphics Card | On-Board graphics
ATI RageXL, 8 MB |
| Benchmarks | |
| Performance Measurements | c’t h2benchw 3.6 |
| I/O Performance | IOMeter 2003.05.10
Fileserver Benchmark Webserver Benchmark Database Benchmark Workstation Benchmark |
| Software and Drivers | |
| Operating System | Microsoft Windows Server 2003 Enterprise Edition, Service Pack 1 |
| Platform Drivers | Intel Chipset Installation Utility 7.0.0.1025 |
| Graphics Driver | Default Windows Graphics Driver |
Setup For SYSmark2004 SE
| System Hardware | |
|---|---|
| Processor | Intel Core 2 Extreme X6800 (Conroe 65 nm, 2.93 GHz, 4 MB L2 Cache) |
| Motherboard | Gigabyte GA-965P-DQ6 2.0
Chipset : Intel 965P, BIOS : F9 |
| Common Hardware | |
| RAM | 2x 1024 MB DDR2-1111 (CL 4.0-4-4-12)
Corsair CM2X1024-8888C4D XMS6403v1.1 |
| Graphics Card | HIS X1900XTX IceQ3
GPU : ATI Radeon X1900XTX (650 MHz) RAM : 512 MB GDDR3 (1550 MHz) |
| Hard Drive I | 150 GB, 10,000 RPM, 8 MB Cache, SATA/150
Western Digital WD1500ADFD |
| Hard Drive II | 400 GB, 7,200 RPM, 16 MB Cache, SATA/300
Western Digital WD4000KD |
| DVD-ROM | Gigabyte GO-D1600C (16x) |
| Software | |
| ATI Drivers | Catalyst Suite 7.1 |
| Intel Chipset Drivers | Software Installation Utility 8.1.1.1010 |
| Intel RAID Drivers | Matrix Storage Manager 6.2.1.1002 |
| DirectX | Version : 9.0c (4.09.0000.0904) |
| Operating System | Windows XP, Build 2600 SP2 |
| Benchmarks and Settings | |
| SYSmark | Version 2004 Second Edition
Official Run |
Data Transfer Diagrams
Western Digital WD4000KD (7,200 RPM), Single Drive

Western Digital WD4000KD (7,200 RPM), RAID 0

Western Digital WD1500 (10,000 RPM), Single Drive

Western Digital WD1500 (10,000 RPM), RAID 0


Interface Performance

Read Transfer Rates

Write Transfer Rates







Application Performance: PCMark05 Write Performance

Application Performance: SYSmark 2004 SE


The conclusion for our reissued battle between the current 150 GB WD Raptor and the pair of 400 GB WD4000KD hard drives in RAID 0 is surprising. Although the WD Raptor clearly remains the fastest Serial ATA desktop hard drive, the RAID 0 array beats it in most benchmarks except access time and I/O performance. The cost per gigabyte ratio of the Raptor is particularly questionable, as you can get three times the storage capacity for half the money today, which has mainstream drives beating the Raptor by a factor of six. Enthusiasts willing to accept the higher risk of data loss in RAID 0 should carefully consider a RAID array consisting of two cheap 7,200 RPM drives over the WD Raptor.
500 GB drives will drop below $100 within the next months. At the same time, the storage demands for multimedia keep increasing with high definition video, audio and images. Finally, storage densities keep increasing, and will result in even faster 7,200 RPM drives soon. All of this makes the Raptor look less attractive to users with common sense.
I believe that Western Digital should reconsider its Raptor pricing, because the premium for the cherry on the performance cake at the expense of storage capacity is ridiculously high. It would also be nice to see a refreshed Raptor with 300 GB or more - perhaps even being a hybrid hard drive with built-in Flash memory for Windows Vista?
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