Notebook hard drives square off at 7,200 RPM

In the world of 2.5″ storage devices, solid-state drives deserve all the attention they’re getting. SSDs represent a fundamental shift in storage technology, and new paradigms don’t come along that often. They don’t always come with this big of a step up in performance, either. Thanks to near-instantaneous access times, solid-state drives have quickly become the preferred home for a desktop PC’s OS and applications. True to the roots of their 2.5″ form factor, SSDs are arguably even more attractive for notebooks, which are a perfect fit for their excellent shock tolerance and snappy responsiveness.

Even though prices have fallen dramatically over the last several years, solid-state storage remains a costly proposition, at least on a cost-per-gigabyte basis. That’s easy enough to work around on a desktop, where one has the luxury of installing additional hard drives. Secondary drive bays are rare in notebooks, however; you’re not likely to find one outside portly gaming systems you wouldn’t want on your lap.

In most notebooks, then, everything must be squeezed onto a single internal disk. If you can diet down to 120GB, you’re looking at around $220 for a decent SSD. Pare your digital payload to less than 60GB, and you’ll only pay around $150. Cut it to 40GB, and the price drops to around $100. Any way you slice it, some serious belt-tightening will be in order. The process is likely to be especially painful for anyone using a laptop as his primary PC.

You don’t have to go the solid-state route, though. For only $10 more than the average 40GB SSD, Seagate’s latest Momentus notebook drive offers a whopping 750GB at 7,200 RPM. At the same spindle speed, Samsung’s Spinpoint MP4 will take you to 640GB for only $90. Hitachi and Western Digital are a little behind on capacity among 7,200-RPM notebook drives, but then you’ll only pay $75 for the latest 500 Travelstar and $70 for the latest Scorpio. As appealing as solid-state drives surely are, any of those four mechanical options is a much more tenable compromise for the vast majority of notebook users.

After exploring what this quartet of hard-drive makers had to offer desktops with our 7,200-RPM terabyte round-up, I couldn’t resist probing the pack’s mobile offerings. Rather than focusing on a common capacity, we’ve taken the best 7,200-RPM model from each manufacturer’s stable of notebook drives. These turbo-charged 2.5-inchers will go up against each other, of course, and they’ll also face every other drive we’ve run through our current gauntlet of storage tests: 15 SSDs, 10 desktop drives, a handful of older notebook units, and even a mechanical/SSD crossbreed. So, without further ado, let’s see how the finest 7,200-RPM notebook offerings fare.

And then there were four… more
Before exploring how the performance of these notebook drives compares to a broader range of not-so-direct competition, we should take a moment to consider how they stack up against each other. There are quite a few common elements between the drives, starting with their shared 7,200-RPM spindle speed. That’s a healthy jump in rotational speed over the 5,400-RPM drives that come installed in most notebooks. On the desktop, 5,400-RPM spindle speeds are typically confined to slow, low-power models better suited to secondary mass storage than duty as system drives.

In addition to sporting the same spindle speed, all of the drives have 3Gbps Serial ATA interfaces. 6Gbps SATA is the new hotness, I know, but these notebook models won’t be sustaining transfer rates that surpass the bandwidth provided by a first-gen 1.5GBps SATA link, let alone the 3Gbps one we’ve been using for years. The only transfers that even have a hope of pushing into 3Gbps territory are short bursts to and from the drive’s DRAM cache. Incidentally, the size of that cache is another shared attribute—16MB across the board.

Another similarity among these drives is the fact that they all use two platters, which seems to be the practical limit for 2.5″ models aiming to slide under the 9.5-mm thickness ceiling imposed by most notebook drive bays. Despite the common platter count, we still get a range of capacities. Seagate is the only one to bring 750GB into the 7,200-RPM realm and actually have product on store shelves. Hitachi has announced a Travelstar 7K750 with similar specifications, but it’s not available for sale just yet, so we’re stuck with the 500GB 7K500. Western Digital’s Scorpio Black line also tops out at 500GB, and that model came out later than expected, putting the company a little behind its competition. Samsung has taken an intermediate step up to 640GB.

Increasing the number of bits crammed into every square inch of platter area is key to climbing the capacity ladder. Improving this areal density has performance implications, too. Higher areal densities put more data under the drive head with each rotation, which usually leads to faster sequential transfer rates. Smaller bits do require more precise tracking, though, and that’s not easy when the microscopic target is moving at the equivalent of up to 50 miles an hour.

With 375GB per platter, the Momentus obviously has the highest areal density. Samsung isn’t too far behind with the Spinpoint, whose areal density is higher than one might expect from 320GB platters. The Scorpio and Travelstar both employ 250GB platters, with the Scorpio having a slight edge in data density. I’m curious to see how that pair compares in our sequential throughput tests.

Obviously, storage capacity factors into the pricing equation for all these drives. The more gigabytes you get, the more you’re going to pay. We’ll consider value in the context of capacity and performance a little later in the review, so there’s no need to dwell too much on these sticker prices. I only mention them again because, wow, the cream of the crop for 7,200-RPM notebook drives is pretty affordable.

Even with the lowest asking price of the bunch, the Scorpio Black has an ace up its sleeve that the others can’t match: five years of warranty coverage. Three-year warranties are common among mechanical hard drives, but WD kicks in a couple of years of additional coverage with its premium Black models. Seagate does something similar with its XT family, but the 750GB Momentus isn’t a member.

Our testing methods
Before dipping into pages of benchmark graphs, let’s set the stage with a quick look at other the players we’ve assembled for comparative reference. We’ve called up a wide range of competitors, including a selection of desktop hard drives, traditional notebook drives, Seagate’s Momentus XT hybrid, and a stack of pure solid-state goodness. Below is a chart highlighting some of the key attributes of the contenders we’ve lined up to face our quartet of 7,200-RPM notebook drives.

Although performance results for the 3.5″ drives aren’t entirely relevant to our focus on notebook models, they do provide a handy point of reference for desktop users. Despite much higher prices, SSDs share the same 2.5″ form factor as mechanical notebook drives. Like it or not, they’re direct competition.

On the SSD front, we’ve collected all the other relevant players, including drives based on Indilinx, Intel, JMicron, Marvell, SandForce, and Toshiba controllers. Although it might not seem like a fair fight, we’ve also thrown in results for a striped RAID 0 array built using a pair of Intel’s X25-V SSDs. The X25-V only runs a little more than $100 online, making multi-drive RAID arrays affordable enough to be tempting for desktop users. Our X25-V array was configured using Intel’s P55 storage controller, the default 128KB stripe size, and the company’s latest 9.6.0.1014 Rapid Storage Technology drivers.

The block-rewrite penalty inherent to SSDs and the TRIM command designed to offset it both complicate our testing somewhat, so I should explain our SSD testing methods in greater detail. Before testing the drives, each was returned to a factory-fresh state with a secure erase, which empties all the flash pages on a drive. Next, we fired up HD Tune and ran full-disk read and write speed tests. The TRIM command requires that drives have a file system in place, but since HD Tune requires an unpartitioned drive, TRIM won’t be a factor in those tests.

After HD Tune, we partitioned the drives and kicked off our usual IOMeter scripts, which are now aligned to 4KB sectors. When running on a partitioned drive, IOMeter first fills it with a single file, firmly putting SSDs into a used state in which all of their flash pages have been occupied. We deleted that file before moving onto our file copy tests, after which we restored an image to each drive for some application testing. Incidentally, creating and deleting IOMeter’s full-disk file and the associated partition didn’t affect HD Tune transfer rates or access times.

Our methods should ensure that each SSD is tested on an even, used-state playing field. However, differences in how eagerly an SSD elects to erase trimmed flash pages could affect performance in our tests and in the real world. Testing drives in a used state may put the TRIM-less Plextor SSD at a disadvantage, but I’m not inclined to indulge the drive just because it’s using a dated controller chip.

To make our massive collection of results a little easier to interpret, we’ve colored our bar charts by drive type. This color coding separates the SSDs from the mechanical drives and highlights the four 7,200-RPM notebook models that are the focus of this round-up.

Most of our tests run on drives connected as secondary storage, so we were able to use the Caviar Green’s full 3TB with our test system’s default configuration, which uses the Microsoft AHCI drivers built into Windows 7. However, as we explained in our review, the Green has issues operating at full capacity when running as a system drive, at least with current drivers and non-EFI BIOSes. Rather than moving the Green to an auxiliary storage controller that sees the Caviar’s full capacity as a system drive, we’d rather stick with the motherboard’s P55 chipset and live with slightly less capacity. Switching storage controllers would make the results less comparable, and the impact of running the Green at a little less than full capacity should be negligible considering that our boot and system partition only amounts to 100GB, most of which is unused.

With few exceptions, all tests were run at least three times, and we reported the median of the scores produced. We used the following system configuration for testing:

You can read more about the hardware that makes up our twin storage test systems on this page of our VelociRaptor VR200M review. Thanks to Gigabyte for providing the twins’ motherboards and graphics cards, OCZ for the memory and PSUs, Western Digital for the system drives, and Thermaltake for SpinQ heatsinks that keep the Core i5s cool.

We used the following versions of our test applications:

• WorldBench 6
• Intel IOMeter 2006.07.27
• Xbit Labs File Copy Test 0.3
• HD Tune 4.01
• Visual Studio 2008 with 03-23-2010 Firefox source
• Call of Duty: Modern Warfare 2
• Crysis Warhead

The test systems’ Windows desktop was set at 1280×1024 in 32-bit color at a 75Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.

Most of the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

HD Tune
We’ll kick things off with HD Tune, our synthetic benchmark of choice. Although not necessarily representative of real-world workloads, HD Tune’s targeted tests give us a glimpse of a drive’s raw capabilities. From there, we can explore whether the drives live up to their potential.

I’ve removed the SSDs and desktop drives from the line graphs because the data is too densely packed to be readable. Plus, Excel really doesn’t have enough colors. If you’d like an idea of how the SSD transfer-rate profiles look in comparison, check out this page of our 7,200-RPM terabyte round-up.

So much for areal density dictating sequential throughput. The 750GB Momentus is a little slower than the Spinpoint in HD Tune’s sustained read speed test, and although we don’t know the Samsung drive’s areal density, it’s almost certainly lower than the Seagate’s. In the battle of 500GB drives, the Travelstar edges out the Scorpio despite packing 30 fewer gigabits per square inch.

Right from the gun, it’s apparent solid-state drives have a big performance advantage. What’s more interesting is how these 7,200-RPM notebook models fare against other 2.5″ mechanical drives. The Scorpio Blue spins its platters at 5,400 RPM and is a good 10MB/s slower than the Scorpio Black, putting it nearly 20MB/s behind the Spinpoint. Seagate’s Momentus XT doesn’t look so hot, either; it’s slower than the Scorpio Blue despite having a 4GB solid-state read cache backed by 7,200-RPM mechanical storage.

In the line graphs, notice how the XT’s transfer rates fall off quickly and oscillate more frequently than the purely mechanical drives. The transfer-rate profiles of our 7,200-RPM contenders are more consistent, although the Momentus’ read speed falls off in more of a stair-step fashion than the others.

Switching to writes narrows the gaps between the 7,200-RPM notebook drives, but their order doesn’t change. Even though the Momentus XT is a little more competitive this time around, it still lags behind the Scorpio Black. Our lone 5,400-RPM example remains a ways off the pace, as well.

SSDs tend to read faster than they can write, and that has interesting implications for this particular test. Although the fastest solid-state drives still rule the standings, our collection of notebook drives is quicker than Intel’s budget X25-V and not much slower than the X25-M. Intel SSDs have traditionally had sluggish write performance, at least in tests of flat-out sequential throughput.

Before moving on, note the Spinpoint’s more erratic oscillations in our line graph. They still average out to the highest sustained write speed, but it’s a bumpier ride than with reads.

Next up: some burst-rate tests that should test the cache speed of each drive. We’ve omitted the X25-V RAID array from the following results because it uses a slice of system memory as a drive cache.

Our notebook drives might all have 16MB of DRAM onboard, but the speed of that cache differs between the various models. The Spinpoint and Travelstar flirt with 200MB/s in HD Tune’s burst speed tests, while the Scorpio and Momentus languish 27-38MB/s behind.

Our HD Tune tests conclude with a look at random access times, which the app separates into 512-byte, 4KB, 64KB, and 1MB transfer sizes. Let’s start with reads.

In a bit of a surprise, the Scorpio Black ascends to the top of the heap with three of four transfer sizes. The Momentus takes over at the 1MB transfer size, and the two are tied at 64KB. Meanwhile, the Spinpoint and Travelstar find themselves in third and fourth place, respectively. They’re only a few milliseconds shy of the leaders to start, but that delta grows with the transfer size.

As you can see, this is fertile ground for the SSDs, whose silicon-based storage offers much faster access times than mechanical platters. The Momentus XT’s read cache proves useful with the smaller transfer sizes, but it runs out of steam at 1MB, plunging the XT behind our two leaders.

What happens when we switch to random writes?

The Momentus 750GB tanks. Through all four transfer sizes, the Seagate drive ends up at the back of our 7,200-RPM pack, often by substantial margins. Random writes don’t faze the Scorpio Black, which maintains its position at the head of the class. Behind it, the Spinpoint and Travelstar jockey for second place, with Hitachi slipping ahead at smaller transfer sizes and Samsung winning out at larger ones.

Because its solid-state component is exclusively a read cache, the Momentus XT’s hybrid nature doesn’t help it in these random-write tests. The SSDs continue to dominate, although they’re not as far ahead of the mechanical pack as in the random-read tests.

File Copy Test
Since we’ve tested theoretical transfer rates, it’s only fitting that we follow up with a look at how each drive handles a more typical set of sequential transfers. File Copy Test is a pseudo-real-world benchmark that times how long it takes to create, read, and copy files in various test patterns. We’ve converted those completion times to MB/s to make the results easier to interpret.

Windows 7’s intelligent caching schemes make obtaining consistent and repeatable performance results rather difficult with FC-Test. To get reliable results, we had to drop back to an older 0.3 revision of the application and create our own custom test patterns. During our initial testing, we noticed that larger test patterns tended to generate more consistent file creation, read, and copy times. That makes sense, because with 4GB of system memory, our test rig has plenty of free RAM available to be filled by Windows 7’s caching and pre-fetching mojo.

For our tests, we created custom MP3, video, and program files test patterns weighing in at roughly 10GB each. The MP3 test pattern was created from a chunk of my own archive of ultra-high-quality MP3s, while the video test pattern was built from a mix of video files ranging from 360MB to 1.4GB in size. The program files test pattern was derived from, you guessed it, the contents of our test system’s Program Files directory.

Even with these changes, we noticed obviously erroneous results pop up every so often. Additional test runs were performed to replace those scores.

Our 7,200-RPM notebook drives are all over the place when tasked with file creation, and the standings very much depend on the file set used. With MP3s, the pack is tightly bunched, and the Spinpoint comes out on top. Switch to program file set, which has smaller files and more of them, and the Momentus jumps out to a healthy lead. Seagate stays out in front with the video file set, which is made up of a handful of very large files.

The SSDs are spread up and down the standings here, with some struggling with specific test patterns and others succumbing to slower write speeds. Sluggish write performance won’t affect the FC-Test’s read component, though.

Solid-state solutions perform better here as a whole, but there are a few exceptions. Speaking of exceptions, the Travelstar and Momentus both fall flat when reading the MP3 file set, turning in transfer rates less than half the speed of the Scorpio and Spinpoint. The Seagate bounces back in impressive fashion, shooting to the head of the class with the program file set and nudging behind the Spinpoint with our collection of video files. The Hitachi also looks more competitive with the video file set, but it’s still more than 20MB/s behind with program files.

The Momentus 750GB tops all three copy tests, although it shares the lead with the Spinpoint in one of them. In the other file sets, the Momentus’ margin of victory is more pronounced. Interestingly, those file sets also show the other 7,200-RPM notebook drives on roughly equal footing.

File copy speed
Although FC-Test does a good job of highlighting how quickly drives read, write, and copy different types of files, the app is antiquated enough to completely ignore the command queuing logic built into modern hard drives and SSDs. FC-Test only uses a queue depth of one, while Native Command Queuing can stack up to 32 I/O requests when asked. To get a better sense of how these drives react when moving files around in Windows 7, we performed a set of hand-timed copy tests with 7GB worth of documents, digital pictures, MP3s, movies, and program files. These files were copied from the drive to itself to eliminate any other bottlenecks.

We run this test on SSDs in a factory fresh and simulated used state since there are often performance differences between those two conditions. To put our SSDs into a simulated used state, I run our IOMeter workstation access pattern with 256 concurrent I/O requests for 30 minutes before launching into a second batch of copy tests.

IOMeter creates a massive test file that spans the entirety of a drive’s capacity, and deleting it to make room for a batch of copy tests nicely puts solid-state drives into a tortured used state. What we’ve essentially done here is filled all of an SSD’s flash pages, subjected the drive to a punishing workload with a highly-randomized access pattern, and then marked all of the flash pages as available to be reclaimed by garbage-collection or wear-leveling routines.

Mechanical hard drives aren’t subject to the block-rewrite penalty that causes SSD performance degradation as flash pages become occupied, so there’s no difference between their fresh- and used-state performance. We’ve double-checked to be sure. To avoid confusing the issue, we’ve omitted the fresh-state copy speeds of the SSDs in the graph below.

What works for FC-Test doesn’t necessarily pay dividends in the real world, at least when it comes to the Momentus 750GB. In our Windows 7 copy test, the Momentus consistently turned in much slower transfer rates than the others, which were led by the Spinpoint. The diverse collection of files we use for this test seems to be throwing the Momentus well off its game, which is surprising given the relatively modest performance differences between the other notebook drives.

This real-world copy test gives us a good look at just how much faster SSDs can perform a relatively simple task—well, some of them, anyway. Our 7,200-RPM notebook offerings don’t do too badly, though. They’re faster than low-power desktop drives and much quicker than the 5,400-RPM Scorpio Blue.

Application performance
We’ve long used WorldBench to test performance across a broad range of common desktop applications. The problem is that few of those tests are bound by storage subsystem performance—a faster hard drive isn’t going to improve your web browsing or 3ds Max rendering speeds. A few of WorldBench’s component tests have shown favor to faster hard drives in the past, though, so we’ve included them here.

Our application tests don’t tease out big differences between the notebook drives in the crosshairs today. However, there are a couple of interesting tidbits we can glean from the reaults. First, the Spinpoint is notably slower in both Nero and Photoshop. Second, the Momentus 750GB completes our Firefox compile slower than everything else we’ve tested.

I know what you’re thinking, and yes, the Momentus’ margin of defeat with the Firefox compile is tiny when you consider the overall duration of the test. What interests me here is that it’s slower at all; the other 7,200-RPM notebook drives finish within a few seconds of each other. In just over half an hour, our Firefox compile generates over 22,000 files totaling around 900MB. This may be another clue that the Momentus has trouble dealing with a high volume of smaller files.

Boot and load times
Our trusty stopwatch makes a return for some hand-timed boot and load tests. When looking at the boot time results, keep in mind that our system must initialize multiple storage controllers, each of which looks for connected devices, before Windows starts to load. You’ll want to focus on the differences between boot times rather than the absolute values.

This boot test starts the moment the power button is hit and stops when the mouse cursor turns into a pointer on the Windows 7 desktop. For what it’s worth, I experimented with some boot tests that included launching multiple applications from the startup folder, but those apps wouldn’t load reliably in the same order, making precise timing difficult. We’ll take a look at this scenario from a slightly different angle in a moment.

Only three seconds separate the fastest 7,200-RPM notebook drive from the slowest in our boot-time test. The Momentus is responsible for most of that, since our top three contenders are all within about a second of each other, with the Travelstar leading the way.

A faster hard drive is not going to improve frame rates in your favorite game (not if you’re running a reasonable amount of memory, anyway), but can it get you into the game quicker?

Seagate redeems itself in our level-load tests, finishing each one faster than its direct competition. The Scorpio and Travelstar aren’t too far behind here, but the Spinpoint is notably slower, especially in Crysis Warhead.

Our boot- and load-time tests present a pretty good case for solid-state drives, which are faster nearly across the board, and by margins large enough that you’re likely to notice. Speaking of margins you’re likely to notice, the 5,400-RPM Scorpio Blue is substantially slower than our 7,200-RPM offerings in all three tests.

Disk-intensive multitasking
TR DriveBench allows us to record the individual IO requests associated with a Windows session and then play those results back on different drives. We’ve used this app to create a new set of multitasking workloads that should be representative of the sort of disk-intensive scenarios folks face on a regular basis.

Each workload is made up of two components: a disk-intensive background task and a series of foreground tasks. The background task is different for each workload, but we performed the same foreground tasks each time.

In the foreground, we started by loading up multiple pages in Firefox. Next, we opened, saved, and closed small and large documents in Word, spreadsheets in Excel, PDFs in Acrobat, and images in Photoshop. We then fired up Modern Warfare 2 and loaded two special-ops missions, playing each one for three minutes. TweetDeck, the Pidgin instant-messaging app, and AVG Anti-Virus were running throughout.

For background tasks, we used our Firefox compiling test; a file copy made up of a mix of movies, MP3s, and program files; a BitTorrent download pulling seven Linux ISOs from 800 connections at a combined 1.2MB/s; a video transcode converting a high-def 720p over-the-air recording from my home-theater PC to WMV format; and a full-disk AVG virus scan.

DriveBench produces a trace file for each workload that includes all IOs that made up the session. We can then measure performance by using DriveBench to play back each trace file. During playback, any idle time recorded in the original session is ignored—IOs are fed to the disk as fast as it can process them. This approach doesn’t give us a perfect indicator of real-world behavior, but it does illustrate how each drive might perform if it were attached to an infinitely fast system. We know the number of IOs in each workload, and armed with a completion time for each trace playback, we can score drives in IOs per second.

Below, you’ll find an overall average followed by scores for each of our individual workloads. The overall score is an average of the mean performance score in each multitasking workload.

DriveBench doesn’t produce reliable results with Microsoft’s AHCI driver, forcing us to obtain the following performance results with Intel’s 9.6.0.1014 RST drivers. We couldn’t get DriveBench to play nicely with our the X25-V RAID config, either, which is why it’s not listed in the graphs below. The app will only run on unpartitioned drives, so we tested drives after they’d completed the rest of the suite.

As we’ve mentioned, Intel’s current RST drivers don’t properly support 3TB hard drives. Instead of detecting the Green’s full capacity, we were limited to the latter 746GB of the drive. That’s still enough capacity to run our DriveBench workloads, but given that the Intel drivers aren’t handling the Green properly, I’m hesitant to draw too many conclusions from the results.

Well, that’s pretty definitive, isn’t it? The Scorpio Black has a resounding lead over its direct competition, leaving the Momentus and Spinpoint to fight over second place. SSDs dominate the results, suggesting that the Scorpio’s quick access times could be responsible for its strong showing here.

Let’s break down the overall average into individual test results to see if anything stands out.

The Scorpio’s domination is pretty complete. Western Digital comes out ahead across all five workloads, and its margins of victory are often substantial.

As one might expect given the test results we’ve seen thus far, the Momentus fares relatively poorly when a Firefox compile or file copy is added to its multitasking workload. The drive comes back strong with the other workloads, but not by enough to overcome the damage done to its overall score.

Curious to see whether removing the multitasking element of these tests would have any bearing on the standings, I recorded a control trace without a background task.

Interesting. Our control test narrows the gap between the Momentus and Scorpio, but it doesn’t do much to help the Spinpoint or Travelstar. The Scorpio is clearly the fastest even when we’re not engaged in demanding multitasking, which hurts the Momentus more than it does the others.

DriveBench lets us start recording Windows sessions from the moment the storage driver loads during the boot process. We can use this capability to take another look at boot times, again assuming our infinitely fast system. For this boot test, I configured Windows to launch TweetDeck, Pidgin, AVG, Word, Excel, Acrobat, and Photoshop on startup.

This mock startup test isn’t as relevant as our real-world example, but it’s interesting to note that the 5,400-RPM Scorpio Blue ties the Spinpoint and finishes ahead of the Travelstar. The Momentus and Scorpio Black are faster still, with Western Digital leading the way.

IOMeter
Our IOMeter workloads are made up of randomized access patterns, presenting a good test case for both seek times and command queuing. The app’s ability to bombard drives with an escalating number of concurrent IO requests also does a nice job of simulating the sort of demanding multi-user environments that are common in enterprise applications.

SSDs are orders of magnitude faster than mechanical hard drives in this test, and that makes graphing the results rather challenging. So we didn’t. The graphs below only have results from the 2.5″ mechanical hard drives. If you’d like to see how the SSDs and desktop drives compare, scroll down this page of our four-way 7,200-RPM terabyte comparison.

Score another one for the Scorpio Black 500GB, at least overall. The WD drive has the highest transaction rates in the file server access pattern, although it must share the glory with the Momentus 750GB in the web server, workstation, and database access patterns.

Both of those models are well ahead of the Spinpoint and Travelstar, which offer lower transaction rates across all four access patterns. The Travelstar is clearly the worst of those two, especially between the extremes of our scaling load. Of course, it still does better than the Momentus XT hybrid, whose transaction rates inexplicably flat-line until we hit 32 outstanding I/O requests.

Power consumption
For our power consumption tests, we measured the voltage drop across a 0.1-ohm resistor placed in line with the 5V and 12V lines connected to each drive. We were able to calculate the power draw from each voltage rail and add them together for the total power draw of the drive. The drives were tested while idling and then under an IOMeter load consisting of 256 outstanding I/O requests using the workstation access pattern.

Power consumption is particularly important for notebook drives that draw juice from a battery, and the Momentus and Travelstar seem to be the most efficient. That said, we’re only looking at a 0.2W delta at idle and less than half a watt under load, so the differences aren’t huge.

SSDs typically consume even less power, but don’t expect substantially longer run times. The power consumption of mechanical notebook drives is pretty low overall, especially when one takes into consideration the power draw of other notebook components.

Noise levels
Noise levels were measured with a TES-52 Digital Sound Level meter 1″ from the side of the drives at idle and under an HD Tune seek load. Drives were run with the PCB facing up.

I’ve consolidated the solid-state drives here because they’re all completely silent. The SSD noise level depicted below is a reflection of the noise generated by the rest of the test system, which has a passively-cooled graphics card, a very quiet PSU, and a nearly silent CPU cooler.

Interestingly, these results track nicely with power consumption. The Hitachi and Seagate drives are a little quieter than the ones from Western Digital and Samsung. I do mean a little, though. My ears couldn’t discern a difference between these drives from a few feet away.

Most mechanical hard drives have an Automatic Acoustic Management (AAM) value that can be set between 128 and 254. Manipulating this setting tends not to affect idle noise levels, but it can dramatically impact seek noise and access times. To get an idea of the sort of performance and acoustic range available with our collection of mechanical drives, we’ve tested the seek noise level and random access time of each at the extremes of the AAM scale. By default, most of the mechanical drives had AAM disabled or set to 254, which is the most aggressive seek setting. Seagate is an exception on a couple of fronts. AAM doesn’t appear to work at all on the Barracuda XT, and on the Momentus 750GB, it’s set at 208 by default.

Fiddling with the AAM slider doesn’t change noise levels all that much. There is an impact on impact on seek times, at least with the Travelstar and Spinpoint. Given the similar seek times we observed with the Momentus and Scorpio between the two AAM extremes, I suspect this setting isn’t doing much for either drive.

The value perspective
After spending pages rifling through a stack of performance graphs, it’s time to broaden our horizons a little and take each drive’s price into consideration. First, we’ll look at capacity per dollar.

To establish an even playing field for all the contenders, we’re using Newegg pricing for all the drives. Mail-in rebates weren’t included in our calculations. Rather than relying on manufacturer-claimed capacities, we gauged each drive’s capacity by creating an actual Windows 7 partition and recording the total number of bytes reported by the OS. Having little interest in the GB/GiB debate, I simply took that byte total, divided by a Giga (10⁹), and then by the price. The result is capacity per dollar that, at least literally, is reflected in gigabytes.

On a cost-per-gigabyte basis, our 7,200-RPM notebook drives are pretty evenly matched. The Scorpio and Spinpoint are slightly better deals than the Momentus and Travelstar, but I wouldn’t make a purchasing decision based on this metric alone. This graph does nicely illustrate just how expensive SSDs are for the storage capacity they offer. 3.5″ desktop drives are cheaper still, but not by the order of magnitude that separates the 2.5″ mechanical units from solid-state alternatives.

Overall performance per dollar is up next, but before we get there, we need to come up with an overall performance score for each drive. Using a single number to represent a drive’s performance across a range of different benchmark tests can be tricky business. After reading through numerous papers on the subject, we’ve settled on calculating a harmonic mean of all the results you’ve seen today. A harmonic mean can be useful for quantifying overall performance for a benchmark suite when individual test results can be compared to a reference baseline, and it’s not prone to being skewed by the fact that we have performance differences of several orders of magnitude in some cases. We just happen to have a full suite of results normalized to a performance baseline provided by an ancient 2.5″, 4,200-RPM IBM Travelstar mobile drive, and as you’ll see in a moment, the harmonic mean generates an overall score that nicely tracks with expectations based on the performance we’ve observed thus far.

I should note that we considered using an arithmetic average to calculate our overall score. However, this simple mean is easily skewed by the enormous performance gaps in IOMeter and HD Tune’s random access time tests, which are several orders of magnitude larger than the performance deltas in the other tests. The resulting overall score doesn’t track with expectations based on the performance we’ve already quantified. Weighting the average to account for those orders-of-magnitude differences would have been arbitrary at best, so we’ve settled on a harmonic mean, which seems to provide useful results.

Our overall score includes individual results for DriveBench and IOMeter rather than the averages we presented in the first set of value graphs. There are five DriveBench multitasking loads and four IOMeter access patterns, giving us a total of 19 test results from which to calculate the harmonic mean. This collection of tests is a little biased towards random access patterns rather than sequential transfers, but we think it strikes a good balance for drives that will store a system’s OS and applications. The power-efficiency and noise-level results have been left out to keep this a strictly performance-per-dollar affair.

Because they had to sit out at least one of the tests that make up our overall average, the PX-128M1S and X25-V RAID array haven’t been included in the graphs below. We wouldn’t recommend the former, anyway, and with two drives at its disposal, the RAID config would’ve had an unfair advantage—you know, like it’s had all day already.

No doubt bolstered by its quick access times and strong showing in DriveBench, the Scorpio Black 500GB comes out ahead in our overall performance index. The Spinpoint slides into second place followed closely by the Travelstar, which is only a few percentage points off the pace. Likely as a result of its sluggish file copy speed, the Momentus falls to fourth, although it’s still quite close to the Samsung and Hitachi drives.

I haven’t talked much about the performance of the older Scorpio Black 320GB because it’s not really in the same league as these newer drives, at least on the capacity front. However, the old Black is still pretty fast, and it’s quicker overall than the new one, at least based on the formula we used to generate this score.

SSDs obviously have a huge advantage when we consider overall performance. However, capacity is an equally important component of any storage device. We’ve divided each drive’s overall performance score by its cost per gigabyte to get a look at overall performance per dollar per gigabyte. Try saying that five times fast.

I’ve omitted SSDs from the scatter plots for the sake of readability. Once more, if you’re curious to see how the solid-state field compares, consult this section of our last hard drive round-up.

Our first performance-based value analysis keeps the Scorpio Black 500GB ahead of its 7,200-RPM counterparts. Looking at the scatter plot, it’s easy to see why. The WD drive offers higher performance than its competition while maintaining a low cost per gigabyte.

Another way to look at this data is to divide each drive’s performance by the cost of a complete system built around it. The aim here is to determine whether spending a little (or a lot) more makes sense when the price premium is absorbed as part of the cost of a complete system. The step up from a $70 drive to a $95 one is hardly daunting to start, and once you factor in the cost of a complete build, the price difference practically disappears.

For our system price calculations, we’ve used our test rig as the inspiration for a base config, to which the price of each drive will be added. Our example system includes a Core i5-750, a P55-based ASUS P755D-E motherboard, 4GB of DDR3-1333 memory, a passively-cooled Radeon HD 4850, Antec’s Sonata III enclosure, and Windows 7. Its base price is $814.94, although you’ll probably want to tack on the cost of secondary mass storage for configurations that will use an SSD. That system price is happens to nicely match the prevailing cost of mid-range notebooks, so it works quite nicely for our 2.5″ mechanical drives.

Adding system cost to the equation shuffles the results but not the standings. Once again, Western Digital takes the crown among the four 7,200-RPM notebook drives we’ve assembled for today’s round-up.