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Seagate Momentus XT 750GB Hybrid Hard Drive Review

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AkG

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In 2008 Seagate introduced their very first hybrid hard drive and while it had many issues and only had a brief time in the market, it was a foreshadowing of things to come. It may not have been overly successful, but you could say that its failures led Seagate to the solutions they introduced in 2010 with the innovative Seagate Momentus XT 500GB. For its time the Momentus XT 500GB’s combination of solid state accessible cache and a reasonable capacity gained it an almost cult like following in the enthusiast community. However, there was still room for improvement and with the new second generation Momentus XT ( now in a larger 750GB form) Seagate truly is pushing things to the next level.

With a market that’s increasingly focused upon elevating production and energy efficiency while reducing initial buy-in cost, the idea of hybrid SSD / HDD drives seems to be gaining traction. They tend to offer the best of both worlds and Seagate themselves have stated that within five years they expect 80% of their hard drives to consist of both platter-based and NAND storage components. This is certainly a lofty goal – even for a company with a reputation for innovation – and one that will be difficult to achieve considering the numerous technological and logistical problems which will have to be hurdled. Most importantly, to reach this goal they have to set a very aggressive timeline for themselves with short product / design cycles and aggressive pricing. This in turn gives them a very short window of opportunity to learn from one generation’s mistakes before the next has to be ready for mass production.


In order to achieve some differentiation between this new drive and the older Momentus XT 500GB, Seagate has overhauled the internals and upgraded the firmware for optimal performance. While 750GB - and thus two 375GB platters - is indeed 50% more space than the original 500GB model, as seen recently this is still a bit behind the areal density curve. Lower density may handicap the hard drive portion of the new XT in terms of raw benchmark numbers but our main concern is the cap it inflicts in terms of overall capacity. Competing 2.5” hard drives have already hit the 1TB mark so Seagate will be playing an uphill battle when offering this up as their lineup’s flagship notebook product. This sadly also means all the refinements seen recently in the 3TB Barracuda drive won’t be seen here either.


When asked why a new drive adhered to slightly older density limitations, the answer from Seagate was straightforward: this drive has been in the works for longer than the 500GB platters have been around. Since one of Seagate’s main priorities is long term reliability, it was simply too late to scrap the well proven design and start anew. This also explains why the internal 32MB cache module is DDR1 and not DDR2 and why certain “OptiCache” technologies are absent from this drive. On the positive side, the Momentus XT packed full with other improvements, so the items mentioned previously won’t be missed.


We will get into the firmware refinements later in this review, but the internal hardware changes are evident the moment we see the PCB. The original Momentus XT 500GB came with a paltry 4GB of SLC NAND while the second generation 750GB model comes with 8GB of current generation, SLC NAND with improved performance. It is a shame that this capacity was not further increased since 8GB of accessible high speed storage space is still not enough. Remember, these hybrid drives require that a certain portion of program information be stored in the NAND which in effect speeds up overall load times and performance. Less of this all-important rapidly accessible storage means the benefits of a hybrid setup will only be realized across a small cross section of your most used programs.

Due to volatility within the hard drive market, many will be wondering how much this little slice of tech will cost, and $245 it certainly isn’t cheap for a 750GB hard drive. That’s basically the price of admission into120GB SandForce SF2281 territory so the Momentus has some pretty big shoes to fill if Seagate has any hope of making inroads here.
 
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AkG

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Say Hello to the F.A.S.T. Factor Advantage

Say Hello to the F.A.S.T. Factor Advantage


The new Momentus XT comes equipped with a bucket load of acronyms and buzz words. While we are a society that seems addicted to acronyms, “F.A.S.T.” encompasses an unusually large amount of ideas, capabilities and even design philosophies in one neat tidy and fairly catchy word.



In its most form, FAST - or to use its full official name “the FAST Factor Advantage” - stands for Flash-Assisted Storage Technology. So FAST basically helps makes the Momentus XT 750GB, well…..FAST. This however only tells you what it does and not what it is.

To truly explain what FAST does and more importantly how goes about its tasks, we’ll start with a bit of back story. While the new and improved Momentus XT is considered a second generation hybrid drive, it actually represents Seagate’s third time at bat within the hybrid market. The first iteration – way back in 2008 – wasn’t all that successful since it relied on Microsoft’s Vista OS to perform the lion’s share of the load balancing workload. It was the operating system’s job to figure out what should be stored on the NAND for quick access and what could be left on the hard drive platters. Due to the hybrid algorithms being processed by a bug-filled software instruction set with minimal interaction with the actual hardware layer, Seagate’s original design was doomed to failure.

Lessons were quickly learned and Seagate went back to the drawing board to research exactly what the typical consumer wanted from their high performance storage devices. With the help of extensive focus groups it was realized the “computer experience” boiled down to a few key areas: Reliability, Battery Life, Performance, Price and ease of use. This may sound like an obvious conclusion but these five key items became a foundation for future products. Unfortunately, typical Hard Drives and Solid State Drives are simply incapable – at this time – of providing a great experience in every one of the key areas. Even most hybrid storage devices have trouble meeting Seagate’s criteria since they are anything but easy to use, or suitable for all systems.



This is where FAST comes into the equation. FAST is actually an umbrella term for three very broad feature sets. All three features are in reality numerous algorithms and routines which run in parallel at the firmware level of the Momentus XT 750GB. These three features sets are called: FAST Management, Adaptive Memory Technology and Fast Boot.



At this time FAST is being used primarily as a way to improve Read performance but the Seagate representatives we talked to hinted at future developments which could include writes being handled via FAST as well. This forward thinking methodology would explain why Seagate has stayed with SLC NAND which is less likely to degrade over time than its MLC sibling. This approach has created a somewhat double edged sword but we’ll get to that in a moment. Before continuing we do have to make it crystal clear that all three feature sets interlock and overlap to form a cohesive whole. All three do their part in ensuring only the most important blocks of data are on the NAND.



The first of the three feature sets is FAST Management. This is in turn an umbrella term for various low level algorithms which do numerous things. Its main responsibility is managing the NAND itself and keeping it in tip top shape but it is also responsible for closing off access to the NAND if a module dies. If such an unfortunate situation does occur, FAST Management will alert the user and automatically the XT hybrid drive into a standard Momentus 750GB hard drive, thus ensuring that reliability is never compromised, only performance.

While the how and what these algorithms are and do is a closely guarded secret some things can be inferred. It seems like the algorithms concerned with keeping the NAND out of a degraded state are simply Seagate’s proprietary answer to “Idle Time Garbage Collection” or “Background Garbage Collection” we’ve seen on SSDs.



Since the Momentus XT can be considered for all intents and purposes a large hard drive with a small 8GB SSD attached to its hip, emergency cleaning is going to play a large role for long term performance. TRIM is an obvious impossibility due to a few unavoidable facts. This drive caches at the block level and whole files likely won’t copied to the NAND and the SSD portion is hidden from the computer so BGC / ITGC is the only logical option. We have no doubts that this is a seamless experience which is carried out during low IO periods, as doing anything else would directly impact performance. As long this drive respects sleep commands, how the garbage collection is carried out also does not matter. All that matters is that FAST Management does do its job.

It is also worth pointing out that FAST management is tasked with making sure the “stuttering” or pausing which plagued earlier firmware revisions of the Momentus XT 500GB will never happen. While data blocks are being accessed, the platter portion of a file is being accessed via the arm and platter itself. Seagate states that in extensive testing not once was the dreaded pausing issue ever encountered.
 
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AkG

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Say Hello to the F.A.S.T. Factor Advantage Cont'd

Say Hello to the F.A.S.T. Factor Advantage Cont'd





This brings us to the second feature set: Adaptive Memory Technology which is concerned with what LBAs (logical block addresses) are copied to the NAND and which stay on the hard drive. These algorithms did exist on the first generation Momentus XT 500GB, but have been significantly refined for this iteration. The job of this technology is to monitor - in what we assume is real time - what you use the storage system for and then adapts itself to your particular needs. In practice this should improve overall system performance as the algorithms learn your usage habits and begin storing constantly accessed information on the fast NAND.

Seagate couldn’t divulge exactly what and when this happens but the algorithms themselves boil down to constant monitoring and then quantifying (we assume via a look-up table which keeps “count” of what, when and how often all the blocks are accessed) which blocks need to be on the NAND, which ones no longer need to be stored and which ones are nearly at the threshold of being on the NAND and should be next up for transfer. It then either changes out blocks stored on the NAND on a case by case basis or tells the FAST Management algorithms to do this. This new ability should make the Momentus XT more responsive for your crucial tasks while allowing it to be even more flexible than the previous model.


While Adaptive Memory technology is not new, it is much improved in this generation. Seagate claims that it starts to learn almost instantly and by the fourth usage will be hitting near optimum speeds. This would be impressive as the first generation XT only started to hit its stride by the 6th usage and was not until the 10th – or later - that it had a complete handle on your needs.

Helping to make things even faster is the fact that FAST also allows the controller to access blocks via the NAND while telling the hard drive arm to find the next block on the platter. In real world terms Seagate states this new blending of NAND and platter reads results in a massive improvement in some tests.



From Seagate’s focus groups came the realization that while rebooting a system may only occur once a week for most consumers, the speed at which this happens is one of the main benchmarks we all use for judging how “fast” a system is. In order to accomplish fast boot times, FAST has one more trick up its sleeve: every time you reboot it takes a snapshot exactly which blocks are being accessed and ensures that the most important blocks of data never “fall off” the NAND. It can do this, no matter how infrequently you reboot, because an undisclosed portion of the 8GB is set aside solely for this “Fast Boot” technology.


The down side to this FastBoot is obvious: instead of having twice as much NAND to work with compared to what the first generation Momentus XT has, the 750GB version needs a certain amount of this space dedicated solely for booting. If a system is being mainly used for gaming, would increased boot time – something you rarely do – be as important as games loading as fast as possible? We doubt it but the limited amount of NAND storage space may indeed cause this kind of unwanted tradeoff.
 
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AkG

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Testing Methodology

Testing Methodology



Testing a drive is not as simple as putting together a bunch of files, dragging them onto folder on the drive in Windows and using a stopwatch to time how long the transfer takes. Rather, there are factors such as read / write speed and data burst speed to take into account. There is also the SATA controller on your motherboard and how well it works with SSDs & HDDs to think about as well. For best results you really need a dedicated hardware RAID controller w/ dedicated RAM for drives to shine. Unfortunately, most people do not have the time, inclination or monetary funds to do this. For this reason our testbed will be a more standard motherboard with no mods or high end gear added to it. This is to help replicate what you the end user’s experience will be like.

Even when the hardware issues are taken care of the software itself will have a negative or positive impact on the results. As with the hardware end of things, to obtain the absolute best results you do need to tweak your OS setup; however, just like with the hardware solution most people are not going to do this. For this reason our standard OS setup is used. However, except for the Vista load test times we have done our best to eliminate this issue by having the drive tested as a secondary drive. With the main drive being a Kingston HyperX 240GB Solid State Drive.

For synthetic tests we used a combination of the ATTO Disk Benchmark, HDTach, HD Tune, Crystal Disk Benchmark, IOMeter, AS-SSD and PCMark Vanatage.

For real world benchmarks we timed how long a single 10GB rar file took to copy to and then from the devices. We also used 10gb of small files (from 100kb to 200MB) with a total 12,000 files in 400 subfolders.


All tests were run 4 times and average results are represented.

In between each test suite runs (with the exception being IOMeter which was done after every run) the drives are cleaned with either HDDerase, SaniErase or OCZ SSDToolbox and then quick formated to make sure that they were in optimum condition for the next test suite.

Processor: Core i5 2500
Motherboard: Asus P8P67 Deluxe
Memory:
8GB Corsair Vengeance "Blue" DDR3 1600
Graphics card: Asus 5550 passive
Hard Drive: Kingston HyperX 240GB, OCZ 480GB RevoDrive3 x2
Power Supply: XFX 850

Unless otherwise noted the drives used were:

Solid State Drives:
Mushkin Chronos 120GB
Corsair Force 3 GT 120GB
Patriot Pyro 120GB

5400rpm:
Western Digital Scorpio Blue 1TB (WD10JPVT)


7200rpm:
Hitachi 7K750 750GB
Seagate Momentus (ST9750420AS) 750GB
Western Digital Scorpio Black 750GB
Seagate Momentus XT 500GB


10,000rpm:
Western Digital Velociraptor (HLFS) 150GB
 
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AkG

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Read Bandwidth / Write Performance

Read Bandwidth


For this benchmark, HDTach was used. It shows the potential read speed which you are likely to experience with these hard drives. The long test was run to give a slightly more accurate picture. We don’t put much stock in Burst speed readings and thus we no longer included it. The most important number is the Average Speed number. This number will tell you what to expect from a given drive in normal, day to day operations. The higher the average the faster your entire system will seem.



As with the previous generation, sequential read performance isn’t enhanced in the least by the NAND in this hybrid setup. The net result is decent results for 2.5” hard drive, but a tad low when compared to what the denser platter – and slower 5400rpm - 1TB models can do. In other words – and as expected - this new Momentus XT 750GB acts a lot like a standard 750GB Momentus.


Write Performance


For this benchmark HD Tune Pro was used. To run the write benchmark on a drive, you must first remove all partitions from that drive and then and only then will it allow you to run this test. Unlike some other benchmarking utilities the HD Tune Pro writes across the full area of the drive, thus it easily shows any weakness a drive may have.



Since FAST is not – currently – configured to deal with write requests, it came as no surprise to see these numbers line up with those from a typical Momentus 750GB, 7200rpm 2.5” hard drive.
 
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AkG

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ATTO Disk Benchmark

ATTO Disk Benchmark


The ATTO disk benchmark tests the drives read and write speeds using gradually larger size files. For these tests, the ATTO program was set to run from its smallest to largest value (.5KB to 8192KB) and the total length was set to 256MB. The test program then spits out an extrapolated performance figure in megabytes per second.





It seems that just like the first generation Seagate Momentus XT, this new 750GB second generation doesn’t use its NAND for ATTO. This certainly does make synthetic testing damn difficult as this is the de-facto standard most manufactures use.
 
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AkG

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Crystal DiskMark / PCMark 7

Crystal DiskMark


Crystal DiskMark is designed to quickly test the performance of your hard drives. Currently, the program allows to measure sequential and random read/write speeds; and allows you to set the number of tests iterations to run. We left the number of tests at 5 and size at 100MB.





While Seagate states that they have refined and improved to a great extent the “Adaptive” abilities of their Adaptive Technology, it seems this doesn’t mean it can handle nearly completely random data like what’s used in Crystal DiskMark. Once again, we are seeing a very decent – if slightly dated – results for a brand new 2.5” hard drive, but nowhere what a Solid State Drive can accomplish


PCMark 7


While there are numerous suites of tests that make up PCMark 7, only one is pertinent: the HDD Suite. The HDD Suite consists of numerous tests that try and replicate real world drive usage. Everything from how long a simulated virus scan takes to complete, to MS Vista start up time to game load time is tested in these core tests; however we do not consider this anything other than just another suite of synthetic tests. For this reason, while each test is scored individually we have opted to include only the overall score.



Now these results are more like it! The first run shows what the hard drive portion of this hybrid is capable of (i.e. just like a standard Momentus 750GB hard dive) since the learning algorithms don’t kick in but the 8th run shows how fast the XT can be. These two numbers are very impressive all by themselves but the difference between the 1st and 4th was particularly telling. We can see exactly how fast the FAST technology and Adaptive Memory technology kicks in and learns your needs. This learning curve is easily one of the shortest we have seen from any Hybrid setup. The trick behind hybrid drives is repetition since they “learn” your usage patterns
 
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AkG

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AS-SSD

AS-SSD


AS-SSD is designed to quickly test the performance of your drives. Currently, the program allows to measure sequential and small 4K read/write speeds as well as 4K file speed at a queue depth of 64. While its primary goal is to accurately test Solid State Drives, it does equally well on all storage mediums it just takes longer to run each test as each test reads or writes 1GB of data.





Sadly, while the PCMark numbers were impressive, the Seagate Momentus XT 750GB results are right back to where they were at the beginning of this review. They are hard drive “slow” with no signs of the NAND and the “hybrid” part of the design entering the equation.
 
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AkG

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Vista Start Up / Adobe CS5 Load Time

Vista Start Up


When it comes to hard drive performance there is one area that even the most oblivious user notices: how long it takes to load the Operating System. While all the other tests were run with a Windows 7 operating system, this particular test uses another older test bed's “day to day” OS (copied over to our new testbed) which has accumulated a lot of crud over the months from installs and removals. We chose the Anti-Virus splash screen as our finish line as it is the last program to be loaded on start up.



Well this is certainly interesting. It is obvious that FastBoot does indeed work and - much like the other parts of FAST - it works bloody well in this case. To put this into context, the new Seagate Hybrid is about as fast as an OCZ Vertex 2 120GB, an SSD widely considered to be the powerhouse drive to beat only a year ago.



Adobe CS5 Load Time


Photoshop is a notoriously slow loading program under the best of circumstances, and while the latest version is actually pretty decent, when you add in a bunch of extra brushes and the such you get a really great torture test which can bring even the best of the best to their knees. Let’s see how our review unit faired in the Adobe crucible.



As with the load times, the XT is a horse of a different color than what the majority of synthetic tests would have lead you to believe. It not only learns a damn sight quicker than the previous model but it seems to learn even faster than any other hybrid model we have ever seen – let alone reviewed. It is also worth pointing out that the firmware which came with our drive feels a bit immature and at times but things should improve before the XT becomes widely available.
 
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AkG

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Firefox Portable Offline / Real World Data Transfers

Firefox Portable Offline Performance


Firefox is notorious for being slow on loading tabs in offline mode once the number of pages to be opened grows larger than a dozen or so. We can think of fewer worse case scenarios than having 100 tabs set to reload in offline mode upon Firefox startup, but this is exactly what we have done here.

By having 100 pages open in Firefox portable, setting Firefox to reload the last session upon next session start and then setting it to offline mode, we are able to easily recreate a worse case scenario. Since we are using Firefox portable all files are easily positioned in one location, making it simple to repeat the test as necessary. In order to ensure repetition, before touching the Firefox portable files, we have backed them up into a .rar file and only extracted a copy of it to the test device.

Please note: This test was never designed for hard drives and we have included it only for “informational purposes only” and thus have not included the other 2.5” hard drives. It simply is too tough for any hard disk drive; however where this is a Hybrid it should be able to handle it.




The more we use this drive in “real world scenarios” the more it impresses us. This is the “hardest” test in our benchmarking suite and caters to the unique performance profiles found on SSDs. For any 2.5” hard drive to change so quickly from slow and relatively mediocre performer into a real power house is testament to what Seagate has been able to do in one generation.


Real World Data Transfers


No matter how good a synthetic benchmark like IOMeter or PCMark is, it can not really tell you how your hard drive will perform in “real world” situations. All of us here at Hardware Canucks strive to give you the best, most complete picture of a review item’s true capabilities and to this end we will be running timed data transfers to give you a general idea of how its performance relates to real life use. To help replicate worse case scenarios we will transfer a 10.00GB contiguous file and a folder containing 400 subfolders with a total 12,000 files varying in length from 200mb to 100kb (10.00 GB total).

Testing will include transfer to and transferring from the devices, using MS RichCopy (set to 1 file depth) and logging the performance of the drive. Here is what we found.






This test underscores exactly how little room those wonderfully impressive algorithms and routines have to work with. We know the XT can do better, but since it only has 8GB – and really more like 7.5GB once you take the FastBoot chunk of NAND out of the equation – for its algorithms to work with, it tends to fall behind on the last 20 to 25 percent of data in these tests. The end result is a very, very fast Hybrid SATA drive, but not one that can compete against solid state drives, let alone modern ONFi 2 and Toggle Modern NAND equipped products.
 
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