by Aleksey Meyev
03/10/2009 | 12:29 PM
2.5-inch hard disk drives with a spindle rotation speed of 7200rpm are very specific products in terms of performance and applications. Such models have always been faster than 5400rpm 2.5-inchers but slower than 3.5-inch HDDs. However, the latter point is arguable now because the lower speed of sequential reading and writing of large files is compensated by the lower response time of 2.5-inch HDDs. Why is their response time lower if the spindle rotation speed is the same? Just because their read/write heads move by a smaller distance due to the smaller diameter of the platters (we are talking about averaged distances, of course) and spend less time for that. 7200rpm 2.5-inch drives have always had rather small storage capacities, though. They are inferior to 5400rpm models in this respect because it is harder to ensure correct operation of the heads in maximum-density zones at the higher spindle speed. So, while the engineers have been solving the problem of interaction between the heads and platters in 7200rpm HDDs on the transition from 100GB to 160GB platters, 5400rpm drives have already switched to 250GB platters, increasing both capacity and speed. As a result, 7200rpm 2.5-inch HDDs do not look superior to their 5400rpm counterparts in terms of speed anymore.
The scope of applications for 2.5-inch 7200rpm drives is not wide but stable. Combining small dimensions, reasonable power consumption and good performance, these HDDs have a guaranteed place in top-performance notebooks such as desktop replacements with large (17 inch and more) displays, top-class processors and graphics cards. These products are going to have the best disk subsystem available, especially as the increased cost of the disk wouldn’t matter much in the total cost of the system. For simpler notebooks users may want to prefer 5400rpm drives which are cheaper and more economical.
Another application for 7200rpm 2.5-inchers is in compact servers that need multi-disk arrays. Again, the low power consumption, high performance, low response time and compact size are all serious advantages of such HDDs for this application. And finally, they can also be installed into small and low-noise desktop PCs. Like all 2.5-inchers, 7200rpm drives are far quieter than their 3.5-inch counterparts.
Unfortunately, such HDDs are not widely available. They do not enjoy high demand among retail customers, and most of them go directly to notebook and server makers. The bad practice of paper announcements should be mentioned, too. Press releases and announcements at the developers’ websites are often posted long before the actual release of a HDD model.
Seagate is regularly updating its 7200rpm 2.5-inch HDD series. Each transition to higher-density platters increases the last number in the series name. Now, the 7200.3 series has come to replace the 7200.2 series with 100GB platters (we discussed it in our earlier article). The increased recording density has resulted in an appropriate increase in the storage capacity of the top-of-the-range model. Interestingly, not only senior, but all models of the series now come with a 16MB cache buffer.
By the way, the next series, called Seagate Momentus 7200.4, has been already announced. It is based on 250GB platters but, judging by the lack of such products in shops, this is just another paper announcement. Therefore we will discuss the 7200.3 series only.
Western Digital is a new player in this market sector. The company had used to produce 2.5-inch drives with a spindle rotation speed of only 5400rpm, but some time ago the highly successful Scorpio series split up into two branches: 5400rpm Scorpio Blue and 7200rpm Scorpio Black. All models of the faster series are equipped with 16 megabytes of cache and are currently based on 160GB platters only. The junior model uses one side of one platter and has a storage capacity of 80GB. The senior model is based on two platters and can store 320 gigabytes of data.
Like other brands, Western Digital offers product versions with a velocity sensor that helps park the drive’s heads quickly in case of a fall in order to protect the device from mechanical damage. It is easy to tell such models apart: the second last letter in the model name is J whereas ordinary models have the letter E there. By the way, every Scorpio Black series model has K as the third letter of the model name. The Scorpio Blue series have the letter V there.
Here are the technical specs and firmware versions of the tested devices:
We have picked up a few opponents for them: two previous-generation 7200rpm 2.5-inch drives (with 100GB platters) and the fastest 5400rpm drive we have ever tested so far.
Interestingly, Western Digital declares the same average read seek time for the Scorpio Black as for the Scorpio Blue. Doesn’t the HDD benefit through the increased spindle rotation speed? We will check this out soon.
We also take two 3.5-inch HDDs of the same capacity from the latest generation. Thanks to the large platter size, 320 gigabytes of data fit onto one platter of a modern 3.5-inch HDD rather than on two platters as in 2.5-inch models. The average seek time parameters should be noted again: Seagate thinks it is the same for smaller and larger HDDs whereas Western Digital’s 3.5-inch model takes 2 milliseconds longer to find data.
Every HDD in this test session, save for the Western Digital Scorpio Blue, is equipped with a 16MB cache. While 5400rpm 2.5-inch drives still come with 8 megabytes of cache memory, 16 megabytes is already standard for 7200rpm 2.5-inchers, just like for 7200rpm 3.5-inch products.
The following testing utilities were used:
Testbed configuration:
We installed the generic OS drivers for the drives and formatted them in FAT32 and NTFS as one partition with the default cluster size. For some tests 32GB partitions were created on the drives and formatted in FAT32 and NTFS with the default cluster size, too. The drives were connected to a Promise SATA300 TX4302 controller installed into a PCI-X slot and were switched from the quiet (with Advanced Acoustic Management enabled) into the ordinary operation mode.
We use our internal IOMark tool for low-level tests. Let’s check out the sequential read speed of the drives first.
Now we can compare the HDDs by the read speed at the beginning and end of the partitions created on them.
It is easy to see the progress the models with 160GB platters have made over the previous generation. The recording density being 1.5 times as high as in the previous-generation HDDs, their sequential read speed is about 25% higher. Interestingly, the Seagate 7200.3 is considerably faster than the Western Digital Scorpio Black at both the beginning and end of the partition. The graphs do not change the picture: the data-transfer speed of both HDDs fluctuates depending on how lucky the particular head/surface pair is, but the Seagate is overall faster. It seems to have a somewhat higher recording density with some reserve for further growth. As a result, the Scorpio Black is somewhat slower than its Blue counterpart (which has a lower spindle speed but higher recording density) whereas the Seagate is faster than both products from Western Digital. On the other hand, it is unable to catch up with the last-generation 3.5-inchers (by the way, the 3.5-inch Seagate is ahead of the 3.5-inch Western Digital, too).
And what about cache memory speed?
Judging by the diagram, it is all very simple: the previous-generation 2.5-inch drives are limited by the interface bandwidth whereas the new generation works on full-featured SATA-300 and is no inferior to the 3.5-inch products. Seagate’s HDDs would win this test if it were not for the graphs. If you take a look at them, you can see that the read and write speeds of Seagate’s drives (of both the desktop 7200.11 and compact 7200.2 series) grows up quickly until 256-sector blocks (128KB). Then, there is a sudden slump, especially at writing, followed by a smooth rise. There are performance peaks at data block sizes that are multiples of 256 sectors, but the speed is not high: the read speed remains below 200MBps and the write speed is just barely above 100MBps. Western Digital’s HDDs also have a performance peak at 256-sector blocks, but the performance hit after that peak is not so dramatic. Thus, we think that Western Digital’s products are overall better in this test.
Now let’s proceed from the low-level IOMark to the synthetic IOMeter. IOMeter is sending a stream of read and write requests with a request queue depth of 4. The size of the requested data block is changed each minute, so that we could see the dependence of the drive’s sequential read/write speed on the size of the data block. This test is indicative of the maximum speed the drive can achieve.
The numeric data can be viewed in tables. We’ll discuss graphs and diagrams.
Yes, the increased recording density gives the new HDDs an edge against the older ones in terms of speed. In terms of top speed the HDDs are ranked exactly like in the low-level data-transfer test. When it comes to sequential reading in small data chunks, the Seagate 7200.3 is beyond competition. It is ahead of all the 2.5-inch products, including the Western Digital Scorpio Blue, as well as of both 3.5-inch drives included into the test. In the Western Digital camp the two Scorpios deliver the same speed with large data blocks but the Scorpio Black is ahead with small data blocks.
The picture is different at sequential writing: Western Digital is superior with small data blocks, the Scorpio Black leading the way. However, the latter is slower than the Scorpio Blue and Seagate 7200.3 when processing large data blocks.
In this test IOMeter is sending a stream of requests to read and write 512-byte data blocks with a request queue of 1 for 10 minutes. The total number of requests processed by the HDD is over 60 thousand, so we get a sustained response time that doesn’t depend on the HDD’s buffer size.
Judging by the read response times, the previous-generation 7200rpm 2.5-inch drives are still competitive. They win this test, actually. They are followed by the new 2.5-inchers (the Scorpio Black is half a second faster than the Momentus 7200.3). The 3.5-inch HDDs are on the losing side. Yes, the small diameter of the platters and the shorter movements of the heads ensure a considerable advantage for 2.5-inch drives in response time. The 5400rpm 2.5-inch model is ahead of the 3.5-inchers, too.
The write response time depends on the efficiency of deferred writing algorithms. The 2.5-inch drives from Western Digital have the best write response but the 3.5-inchers seem to have the most efficient algorithms (you can estimate it by the ratio of write to read response). Seagate’s 2.5-inchers from any generation are far from brilliant from this aspect: their write response is higher than that of the other HDDs while their read response is just normal.
Now we’ll see the dependence between the drives’ performance in random read and write modes on the size of the data block size.
We will discuss the results in two ways. For small-size data chunks we will draw graphs showing the dependence of the amount of operations per second on the data chunk size. For large chunks we will compare performance depending on data-transfer rate in megabytes per second. This approach helps us evaluate the disk subsystem’s performance in two typical scenarios: working with small data chunks is typical for databases. The amount of operations per second is more important than sheer speed then. Working with large data blocks is nearly the same as working with small files where the traditional measurement of speed in megabytes per second becomes more relevant.
Let’s start with reading.
IOMeter: Random Read, operations per second
Oddly enough, the previous-generation HDDs take two top places when reading random-address data in small blocks. They enjoy a considerable lead over the new products. This must be the tradeoff for the increased recording density: the new drives take more time to find the necessary point on the platters. Here, the 7200rpm 2.5-inch drives are much faster than both the 5400rpm 2.5-inchers and the 3.5-inchers. By the way, the 3.5-inch Seagate 7200.11 looks especially poor in this test.
IOMeter: Random Read, megabytes per second
As the data chunk grows up to 1 megabyte and larger, it is the sequential read speed that affects a drive’s performance. As a result, the 3.5-inch products go ahead, the old generation of 2.5-inchers falls behind, and the Seagate 7200.3 is faster than the Western Digital Scorpio Black.
IOMeter: Random Write, operations per second
Efficient deferred writing is important for writing in small data blocks. The resulting picture is funny enough: we’ve got such different leaders as Seagate 7200.11 and Western Digital Scorpio Blue. As for the heroes of this review, the Scorpio Black is close to the leaders while the Momentus 7200.3 is last and much slower even than its predecessor Seagate Momentus 7200.2. Seagate’s “fast” compact series seems to be no good at caching.
IOMeter: Random Write, megabytes per second
It is the drive’s sequential speed that comes into play again. As a result, the HDDs rank up exactly as they did in the IOMeter: Sequential Write test.
In the Database pattern the drive is processing a stream of requests to read and write 8KB random-address data blocks. The ratio of read to write requests is changing from 0% to 100% with a step of 10% throughout the test while the request queue depth varies from 1 to 256.
You can click the following link to view the tabled results for IOMeter: Database pattern.
We will build diagrams for request queue depths of 1, 16 and 256.
When the queue depth is zero, Western Digital’s drives are in the lead and close to each other, the Caviar Blue being somewhat behind the 2.5-inchers. It is only at a large number of read operations that the two previous-generation 7200rpm 2.5-inchers (Hitachi 7K200 and Seagate 7200.2) catch up with and outperform the Western Digital team. The high write response time of Seagate’s compact drives shows up here: their performance is lower at high percentages of writes than that of the other HDDs, and the new 7200.3 is inferior to its predecessor. It is a kind of regress instead of progress in the evolution of Seagate’s firmware.
When the queue depth is 16 requests, the drives can reorder requests and put all of their firmware algorithms to use. First place goes to the WD Scorpio Black which is only challenged at pure writing. The Seagate 7200.3 boasts an excellent ability of request reordering when it is receiving read requests only and takes second place then, but it has very low performance at every other load, losing even to its mediocre 7200.2 predecessor. You can also see that the 2.5-inchers are faster than the 3.5-inchers at high percentages of reads (the 5400rpm Scorpio Blue is quite competitive against the Caviar Blue, for example).
When the queue is increased to 256 requests, the peculiarities in the HDDs’ behavior show up even more. Seagate’s products finally demonstrate that they do have deferred writing. It is not aggressive in the 2.5-inch models while the 3.5-inch Seagate 7200.11 speeds up nicely at high percentages of writes. Otherwise, there are no changes among the leaders: the WD Scorpio Black is confidently first, enjoying a large lead over the pursuers. The Caviar Blue and the Scorpio Black share the remaining places on the podium. The Seagate 7200.3 gets closer to the others, yet still cannot leave its last place.
To wind up this part of the test session we will build diagrams with five queue depths for the two heroes of this review.
Judging by the left part of the graphs, the Seagate Momentus 7200.3 has rather good NCQ algorithms. Its deferred writing is very weak, though.
Western Digital seems to use the same firmware as we saw in our reviews of its 5400rpm 2.5-inch drives. This firmware has excellent request reordering algorithms, effective deferred writing, good scalability under increasingly higher load, and has no problematic loads. The diagram is a treat to our eyes.
The drives are tested under loads typical of servers and workstations.
The names of the patterns are self-explanatory. The Workstation pattern is used with the full capacity of the drive as well as with a 32GB partition. The request queue is limited to 32 requests in the Workstation pattern.
The results are presented as performance ratings. For the File-Server and Web-Server patterns the performance rating is the average speed of the drive under every load. For the Workstation pattern we use the following formula:
Rating (Workstation) = Total I/O (queue=1)/1 + Total I/O (queue=2)/2 + Total I/O (queue=4)/4 + Total I/O (queue=8)/8 + Total I/O (queue=16)/16.
Thanks to its low read response time and effective request reordering, the Western Digital Scorpio Black has no rivals as a disk subsystem of a server processing read requests only. On the other hand, the new Seagate 7200.3 is not bad, either. It is better than its predecessor thanks to the lack of a slump under medium loads.
The overall ratings suggest that 2.5-inch drives are obviously superior to 3.5-inch ones at read operations if their spindle rotation speed is the same. And 5400rpm 2.5-inchers are about as fast as 7200rpm 3.5-inchers at such usage.
The addition of write requests leads to interesting changes. The Scorpio Black is still unrivalled but the Scorpio Blue unexpectedly takes second place. Thanks to efficient deferred writing and high recording density this HDD leaves behind the host of the HDDs with faster platters. The weak deferred writing of the Seagate 7200.3 can be seen here: it is slower than its predecessor and, actually, than nearly every of its opponents.
The Western Digital Scorpio is superior again. Basing on this and previous test, it can be recommended for owners of slim servers who are going to build a disk subsystem out of inexpensive 2.5-inch SATA drives.
The Scorpio Black gives way to the Seagate 7200.2 under the Workstation load. The Seagate 7200.3 is slower and competes with the WD Scorpio Blue only.
Take note that the 3.5-inch drives take last places here. Perhaps the PCMark tests will produce a different picture, but the 2.5-inch models are so far better than their 3.5-inch counterparts, being only inferior in terms of top speed at sequential operations.
The HDDs get close to each other when the test zone is limited to 32 gigabytes. The Seagate 7200.11 stands out among the others with its surprisingly high performance (probably due to the high data-transfer rate at the beginning of the disk we have observed above).
Interestingly, the Seagate 7200.3 is somewhat slower than the rather old Momentus 7200.2. High recording density is good, but firmware algorithms must not be neglected, either.
The multithreaded tests simulate a situation when there are one to four clients accessing the virtual disk at the same time, the request queue depth varying from 1 to 8. The clients’ address zones do not overlap. You can click the links below for full test results, but we will only discuss diagrams for a request queue of 1 as the most illustrative ones. When the queue is 2 or more requests long, the speed doesn’t depend much on the number of applications.
When there is only one read thread to be processed, the results depend on the drives’ sequential speeds. The 3.5-inch models have no rivals then while the previous-generation 2.5-inchers with low-density platters are on the losing side. When a second thread is added, Western Digital’s 2.5-inch drives (they have very similar firmware) and the Seagate 7200.3 take the lead. The same goes for three read threads. When there are four threads, WD’s Caviar Blue loses its ground while the Seagate 7200.11 accelerates and takes second place. It is nice to see Seagate’s newer drives have got rid of the common problem of Seagate’s older products – an awful performance at multithreaded reading. The Seagate Momentus 7200.2 is a striking example of that problem.
As opposed to the Seagate 7200.11, the WD Caviar Blue maintains a high speed at multithreaded writing. The new 2.5-inch products are good here and compete for second and third places.
For this test two 32GB partitions are created on the disk and formatted in NTFS and then in FAT32. After that a file-set is created. It is then read from the disk, copied within the same partition and then copied into another partition. The time taken to perform these operations is measured and the speed of the disk is calculated. The Windows and Programs file-sets consist of a large number of small files whereas the other three patterns (ISO, MP3, and Install) include a few large files each, the ISO pattern having the largest files.
We’d like to note that the copying test is indicative of the drive’s behavior under complex load. In fact, the HDD is working with two threads (one for reading and one for writing) when copying files.
FC-Test produces too many numbers, so we will only discuss the NTFS data in the Install, ISO and Programs patterns which cover the entire range of file sizes typical of everyday computing. You can use the links below to view the full results:
Writing files might seem to be the best job for 3.5-inch HDDs, but that’s not so simple in reality. First place indeed goes to the WD Caviar Blue, but second place goes to the WD Scorpio Blue. The Scorpio Black is third. Seagate’s products all deliver modest performance. The compact 7200.3 is good enough at writing small files but slows down to the level of its predecessor with the ISO pattern.
Reading files is the bastion of 3.5-inch HDDs that 2.5-inch models cannot dream of attacking. The difference is especially visible with the large files of the ISO pattern, yet the overall picture is somewhat disturbed by the Seagate 7200.3 which is too good for a 2.5-incher. It performs like 3.5-inch drives with recording density of somewhat lower than 320GB per platter. Many 3.5-inchers of that generation are still working in today’s computers.
The two 2.5-inch drives from Western Digital go neck and neck, the higher spindle rotation speed of the 320GB Caviar Black being successfully made up for by the higher recording density of the 500GB Caviar Blue.
The 3.5-inchers are somewhat faster when copying within the same partition. However, firmware affects performance here: the Seagate 7200.11 and, unfortunately, 7200.3 are too sensitive to the average file size and lose to every Western Digital drive with the ISO pattern.
We can see the same dependence of Seagate products’ performance on the average file size when copying from one partition to another. Western Digital wins this test completely. Take note that the 3.5-inch Caviar Blue is in the lead with large files, but the 2.5-inch Caviar Black overtakes and outperforms it with smaller files.
PCMark04 benchmarks drives in four different modes: Windows XP Startup is the typical disk subsystem load at system startup; Application Loading is the disk activity at sequential starting-up and closing of six popular applications; File Copying measures the HDD performance when copying a set of files; the General Usage parameter reflects the disk activity in a number of popular applications. These four parameters are used to calculate the overall performance rating.
We ran each test ten times and averaged the results.
The 2.5-inch drives are worse than their 3.5-inch counterparts at booting Windows XP up. The Seagate Momentus 7200.3 and the WD Caviar Black have almost identical results.
It is the firmware algorithms that affect the results of the Application Loading test. The WD Scorpio Black beats the 3.5-inchers while the Seagate Momentus 7200.3 falls behind the 3.5-inch HDDs as well as behind the Hitachi 7K200 which has 100GB platters.
Western Digital is absolutely superior in this test.
The General Usage results are similar to what we have seen in the Application Loading subtest: the WD Caviar Black is ahead of the 3.5-inchers while the Seagate Momentus 7200.3 is behind them.
The overall scores are comprehensible enough. WD’s 2.5-inch Scorpio Black and 3.5-inch Caviar Black share the top position while the Seagate Momentus 7200.3 allows the 3.5-inch 7200.11 model to be third. Take note of the last place of the WD Scorpio Blue: the spindle rotation speed is a very important parameter after all. While this HDD is often competitive to the faster models at processing files or under server loads, it is inferior even to products with half its recording density when employed as a system HDD.
PCMark05 is an updated version of the previous benchmark. Instead of File Copying, there is now a File Write trace. A new trace called Virus Scan is added. Its name is self-explanatory.
Again, we performed each test ten times and averaged the results.
These three subtests produce the same standings as the same subtests from the previous version of PCMark, so there is nothing new to discuss.
Most of the job is done within the cache memory in the Virus Scan subtest. The Seagate 7200.3 makes use of that to turn in an impressive win. The second position of the Western Digital Scorpio Blue is a surprise, especially as its 2.5-inch Black mate is only fourth. The Seagate 7200.11 is third here.
As opposed to FC-Test, the HDDs are ranked according to their sequential speeds here except that the Seagate Momentus 7200.3 is almost as fast as the 3.5-inch WD Caviar Blue.
The new subtests have no effect on the overall scores: Seagate Barracuda 7200.11 is the winner.
To make this part of our test session complete, we are going to run the latest version of PCMark called Vantage. Compared with the previous versions, the benchmark has become more up-to-date and advanced in its selection of subtests as well as Windows Vista orientation. Each subtest is run ten times and the results of the ten runs are averaged.
Here is a brief description of each subtest:
Basing on these subtests, the drive’s overall performance rating is calculated.
The change of the operating system and employed application has affected the drives’ standings in the scanning subtest. The Seagate 7200.11 is in the lead now, the WD Scorpio Black and Seagate 7200.2 being second and third, respectively. The new Seagate 7200.3 is second worst here.
Gamers should appreciate the new 2.5-inchers: the WD Scorpio Black is the best of all in this subtest. The Seagate 7200.3 is good, too. It equals the 3.5-inch products and is superior to the drives based on previous-generation platters.
Photographers should use large 3.5-inch HDDs. The Seagate 7200.3 is the best of the 2.5-inch products in this test, yet it is far inferior to the 3.5-inchers. Western Digital’s 2.5-inch HDDs don’t like this load and perform poorly.
The 3.5-inch HDDs are better than their compact counterparts when booting Windows Vista up although the WD Scorpio Black is close to the leaders. The Seagate 7200.3 is in last place, losing to the lower-density drives of the previous generation as well as to the 5400rpm WD Scorpio Blue.
This subtest always produces odd results. It is usually won by HDDs with low response time rather than with high sequential speed as might have been expected. This time, the 2.5-inch drives are unrivalled, the WD Scorpio Black taking first place. Curiously enough, second place goes to the old Seagate Momentus 7200.2 while the 7200.3 is fourth, giving way to the 5400rpm WD Scorpio Blue.
This load is very sensitive to caching. This time the Seagate Momentus 7200.2 proves to have the best algorithms for this subtest. Judging by its result, which is much higher than its sequential speeds, this HDD processed most of the subtest in its cache. The new 2.5-inch 7200rpm drives are good, too. They take second (Western Digital) and third (Seagate) places.
This is yet another test where the drive’s read response time is highly important. The WD Caviar Black is in the lead, followed by the two old 2.5-inch 7200rpm models. The new Seagate Momentus 7200.3 is slow in this subtest.
PCMark Vantage runs under a new OS and uses new applications, producing new results. We’ve got one leader now, the Seagate Barracuda 7200.11. The WD Scorpio Blue and the Seagate Momentus 7200.2 are the losers. The other drives deliver similar performance.
The overall scores are interesting enough. The Seagate Barracuda 7200.11 is first here although has not been brilliant in the previous tests. Second place goes to the old Seagate Momentus 7200.2. The Western Digital Scorpio Black is third while the Seagate Momentus 7200.3 is fourth.
Next goes our homemade test of defragmentation speed. We created a very defragmented file system on a 32GB partition of a hard disk by loading it with music, video, games and applications. Then we saved a per-sector copy of the disk and now copy it to the HDD we want to test. The tested HDD is connected to the mainboard’s SATA controller whose operation mode (AHCI/Standard IDE) is controlled from the mainboard’s BIOS. Next we run a script that evokes the console version of the Perfect Disk 8.0 defragmenter and marks the time of the beginning and end of the defragmentation process. Thus, each drive is tested twice – with AHCI support turned on and off on the controller. You can refer to this article for details about this test.
Unfortunately, we don’t have the test data for the two 2.5-inch drives with 100GB platters (Seagate Momentus 7200.2 and Hitachi 7K200).
Judging by the results, the defragmentation speed depends on both response time and sequential speed of the drive. As a result, the WD Scorpio Black is close to the leading WD Caviar Blue. The WD Scorpion Blue is somewhat slower than the leaders. Seagate’s team are noticeably worse than Western Digital’s, the new Seagate Momentus 7200.3 being the slowest of all in this test.
You can refer to our article called Hard Disk Drive Power Consumption Measurements: X-bit’s Methodology Indepth for details on this test. We’ll just list the specific modes we measure the power consumption in:
Let’s check out each mode one by one. Since this test session focuses on 2.5-inch drives which only consume from a 5V line and compares them with 3.5-inch drives which consume from both 5V and 12V lines, we will be talking about total power consumption. The start-up currents will only be compared for the 2.5-inch models due to the same reason.
The 7200rpm 2.5-inchers are quite modest in terms of the current necessary to start up. Every one of them fits within 1 ampere and should have no problems working in external enclosures powered by two USB ports (of course, you should better install such drives into enclosures with eSATA interface to reveal their full potential, but that’s a topic for a different review). The test is won by the Western Digital Caviar Blue 500GB which is very economical (even in comparison with other 5400rpm drives) but the Seagate Momentus 7200.3 is just a tiny bit worse. The WD Scorpio Black needs a higher current, but again, all of the drives are really good in this test.
The 7200rpm 2.5-inchers consume somewhat more power in idle mode than their 5400rpm mates. The difference is indeed small, only 0.2-0.3W, and even lower with the Hitachi 7K200.
Take note that the 2.5-inch drives are far more economical than the 3.5-inch models. The latter need four times more power and thus generates much more heat. It means that 2.5-inch disks would require less cooling in a densely packed server or compact home PC.
The 7200rpm 2.5-inch drives are not much hungrier than their 5400rpm counterparts at random-address reading and writing. For example, the Seagate Momentus 7200.3 is almost as fast as the WD Scorpio Blue although the latter is among the most economical products in its class. Well, it still does not make it to the level of the latest 5400rpm drives from Seagate (you can view the results of the Seagate Momentus 5400.5 based on two 160GB platters), but that’s the payment for its higher performance. It looks like low power consumption is the priority of modern 2.5-inch drives from Seagate, the inferior speed characteristics being the tradeoff.
The WD Scorpio Black is faster but consumes more. The difference from the Seagate 7200.3 is 0.4W and 0.5W at reading and writing, respectively. This higher power consumption is necessary for the advanced electronics and quick heads, and we guess it is indeed worth the resulting performance benefits.
The 2.5-inch models are not as better than the desktop HDDs as in idle mode: the difference is only twofold now. Anyway, you should remember that larger-capacity 3.5-inch drives will have not one but two or more platters and, accordingly, higher power consumption. And you won’t have much power saving even with 5400rpm 3.5-inchers (but you will have a much higher response time with such models).
The Seagate Momentus 7200.3 delivered higher speeds at sequential operations in our tests and it has high power consumption under such load. It is the most voracious of the tested 2.5-inch drives then, requiring about one third of a watt more than the WD Scorpio Black. The payment for the higher spindle rotation speed is about 0.5W again. The difference between the 2.5-inch and the desktop HDDs is twofold.
We have tested 2.5-inch hard disk drives based on 160GB platters and with a spindle rotation speed of 7200rpm. Of course, they are faster than HDDs of the same form-factor but with a spindle rotation speed of 5400rpm. The higher recording density of the 500GB Western Digital Scorpio Blue helped it leave last place in some tests but mostly due to its very good firmware. It was unable to catch up with the Western Digital Scorpio Black. The difference in power consumption between 2.5-inch drives with different spindle rotation speed is small: about 0.2W in idle mode and 0.5W under load. We are talking about HDDs with similar electronics and actuators, of course. It is quite possible to find a pair of models in which a 7200rpm drive will consume less than a 5400rpm one.
Comparing the participants of this review with the desktop 3.5-inch HDDs, the latter do not have too many advantages. They offer a cheaper cost of storage and large capacity, that’s all. They are not faster anymore. 3.5-inch drives are ahead of their 2.5-inch counterparts in linear speed, i.e. at operations with large files (and such files must not be fragmented). In all other cases, the lower response time of 2.5-inch products helps them compete and often beat their 3.5-inch opponents. Even the 5400rpm Western Digital Scorpio Blue is not much slower than them whereas the WD Scorpio is actually the overall winner of our tests. So, using a 2.5-inch drive in your notebook or desktop PC won’t limit your disk subsystem performance. Perhaps operations with large files will take somewhat longer, but at everyday applications such a computer may prove to be even faster than a computer with a large 3.5-inch drive. And of course, 2.5-inch drives are two and four times more economical than their 3.5-inch counterparts in idle mode and under load, respectively.
And finally, we’d like to say a few words about each model especially as they behaved very differently. The Seagate Momentus 7200.3 is one of the most economical drives in its class and its sequential speeds are the best in the 2.5-inch category (we don’t count in the WD VelociRaptor and models with SAS interface as they are meant for other applications). Unfortunately, this product’s advantages end here. Its firmware is not good enough and its heads are slow. As a result, it is often slower than its predecessor from the Momentus 7200.2 series.
The Western Digital Scorpio Black, on the contrary, has very good firmware that helped it win most of our tests (especially server-like loads). This product is actually free from serious drawbacks and we don’t feel like caviling at small things. Western Digital has made a good debut with this drive in the 7200rpm 2.5-inch product sector.
We are now waiting for Fujitsu and Hitachi to join the race and for the Seagate 7200.4 with 250GB platters to come to shops.
