V+ 128GB SSD Drive Review
Five years ago we made some predictions about the future development of SSD technology and how it would revolutionize PC storage. Rather than vague musings, we predicted that 2010 was the year SSDs would gain widespread acceptance in the mainstream markets. It turns out we were very close to the mark and things are lining up nicely for a paradigm shift that could have interesting long-term repercussions for a variety of knock-on technologies. SDDs have come a long way in terms of reliability and now are reckoned to be able to last longer than tradional HDDs thanks to wear-leveling algorithms and use a fraction of the power they did in 2005. Even as recently as January 2009, a technology article on Tom's Hardware concluded that SSD performance was not yet good enough - how far things have come in the last year.
This article is primarily a review of Kingston's SSDNow V+ 128GB SSD but, since so few people are really clear about SSDs and even many techies have nagging questions about the technology, we thought we should start off with a technology guide showing how this all came about, the Pros and Cons of SSDs versus traditional HDDs and some Frequently Asked Questions about SSDs. Readers familiar with all this can skip straight to the testing section to see benchmarks but surprisingly, even our hardened techies learnt a thing or two about SSDs while compiling the reference material in the next 3 sections.
What's a disruptive technology?
It's something that has poor performance characteristics at present compared to the incumbent or mainstream current solution but the rate of improvement (the slope of the line or curve with regards to time) is such that at some point in the future it will overtake the current leading solution. The best way to illustrate this is with the following graph:
Using HDDs as our example we can see (looking forward from 2005, say) that disk speeds are steadily increasing as we move from ATA-33 to ATA-66, ATA-100, ATA-133 to SATA-1, SATA-2 and (unknown to us in 2005) SATA-3). Capacity doubles every year while the price remains constant. Speed has gone up by a factor of 5 in 20 years which is nothing to sniff at but look at what those SSDs are doing! In 2005 they cost a fortune and are slower than HDDs (really only being used by the military and some enterprise solutions where HDDs just couldn't stand the heat) but they sure are improving fast and prices are bound to come down as volumes increase.
Today they are much faster (we shall see during testing just how much faster than the latest HDDs) and more importantly we will examine the difference in practical terms (such as Windows boot times and application loading times) rather than just theoretical speeds in benchmarks. First though, let's take a look at the advantages and disadvantages and then (hopefully) all your SSD questions will be answered in the following section.
This FAQ is a compilation of information we have gathered from around the Internet and will hopefully answer most questions about Solid State Disk technology and help explain some of the technical jargon for newcomers to this field and explain from a practical point of view how SSDs work. Many of the questions and answers relate to SSDs in Windows 7 systems and were originally from Microsoft related discussion groups and forums too numerous to reference here but a Google (or Bing) search using the question as the search term should find the sources if more detail is needed.
Random Reads: A very good story for SSDs
SSDs tend to be very fast for random reads. Most SSDs thoroughly trounce traditionally HDDs because the mechanical work required to position a rotating disk head isn’t required. As a result, the better SSDs can perform 4 KB random reads almost 100 times faster than the typical HDD (about 1/10th of a millisecond per read vs. roughly 10 milliseconds).
Sequential Reads and Writes: Also Good
Sequential read and write operations range between quite good to superb. Because flash chips can be configured in parallel and data spread across the chips, today’s better SSDs can read sequentially at rates greater than 200 MB/s, which is close to double the rate many 7200 RPM drives can deliver. For sequential writes, we see some devices greatly exceeding the rates of typical HDDs, and most SSDs doing fairly well in comparison. In today’s market, there are still considerable differences in sequential write rates between SSDs. Some greatly outperform the typical HDD, others lag by a bit, and a few are poor in comparison.
Random Writes & Flushes: Your mileage will vary greatly
The differences in sequential write rates are interesting to note, but for most users they won’t make for as notable a difference in overall performance as random writes.
What’s a long time for a random write? Well, an average HDD can typically move 4 KB random writes to its spinning media in 7 to 15 milliseconds, which has proven to be largely unacceptable. As a result, most HDDs come with 4, 8 or more megabytes of internal memory and attempt to cache small random writes rather than wait the full 7 to 15 milliseconds. When they do cache a write, they return success to the OS even though the bytes haven’t been moved to the spinning media. We typically see these cached writes completing in a few hundred microseconds (so 10X, 20X or faster than actually writing to spinning media). In looking at millions of disk writes from thousands of telemetry traces, we observe 92% of 4 KB or smaller IOs taking less than 1 millisecond, 80% taking less than 600 microseconds, and an impressive 48% taking less than 200 microseconds. Caching works!
On occasion, we’ll see HDDs struggle with bursts of random writes and flushes. Drives that cache too much for too long and then get caught with too much of a backlog of work to complete when a flush comes along, have proven to be problematic. These flushes and surrounding IOs can have considerably lengthened response times. We’ve seen some devices take a half second to a full second to complete individual IOs and take 10’s of seconds to return to a more consistently responsive state. For the user, this can be awful to endure as responsiveness drops to painful levels. Think of it, the response time for a single I/O can range from 200 microseconds up to a whopping 1,000,000 microseconds (1 second).
When presented with realistic workloads, we see the worst of the SSDs producing very long IO times as well, as much as one half to one full second to complete individual random write and flush requests. This is abysmal for many workloads and can make the entire system feel choppy, unresponsive and sluggish.
Random Writes & Flushes: Why is this so hard?
For many, the notion that a purely electronic SSD can have more trouble with random writes than a traditional HDD seems hard to comprehend at first. After all, SSDs don’t need to seek and position a disk head above a track on a rotating disk, so why would random writes present such a daunting a challenge?
The answer to this takes quite a bit of explaining, Anand’s article admirably covers many of the details. We highly encourage motivated folks to take the time to read it as well as this fine USENIX paper. In an attempt to avoid covering too much of the same material, we’ll just make a handful of points.
Performance Degradation Over Time, Wear, and Trim
As mentioned above, flash blocks and cells need to be erased before new bytes can be written to them. As a result, newly purchased devices (with all flash blocks pre-erased) can perform notably better at purchase time than after considerable use. While we’ve observed this performance degradation ourselves, we do not consider this to be a show stopper. In fact, except via benchmarking measurements, we don’t expect users to notice the drop during normal use.
Of course, device manufactures and Microsoft want to maintain superior performance characteristics as best we can. One can easily imagine the better SSD manufacturers attempting to overcome the aging issues by pre-erasing blocks so the performance penalty is largely unrealized during normal use, or by maintaining a large enough spare area to store short bursts of writes. SSD drives designed for the enterprise may have as high as 50% of their space reserved in order to provide lengthy periods of high sustained write performance.
In addition to the above, Microsoft and SSD manufacturers are adopting the Trim operation. In Windows 7, if an SSD reports it supports the Trim attribute of the ATA protocol’s Data Set Management command, the NTFS file system will request the ATA driver to issue the new operation to the device when files are deleted and it is safe to erase the SSD pages backing the files. With this information, an SSD can plan to erase the relevant blocks opportunistically (and lazily) in the hope that subsequent writes will not require a blocking erase operation since erased pages are available for reuse.
As an added benefit, the Trim operation can help SSDs reduce wear by eliminating the need for many merge operations to occur. As an example, consider a single 128 KB SSD block that contained a 128 KB file. If the file is deleted and a Trim operation is requested, then the SSD can avoid having to mix bytes from the SSD block with any other bytes that are subsequently written to that block. This reduces wear.
Windows 7 requests the Trim operation for more than just file delete operations. The Trim operation is fully integrated with partition- and volume-level commands like Format and Delete, with file system commands relating to truncate and compression, and with the System Restore (aka Volume Snapshot) feature.
Windows 7 Optimizations and Default Behavior Summary
As noted above, all of today’s SSDs have considerable work to do when presented with disk writes and disk flushes. Windows 7 tends to perform well on today’s SSDs, in part, because they made many engineering changes to reduce the frequency of writes and flushes. This benefits traditional HDDs as well, but is particularly helpful on today’s SSDs.
Windows 7 will disable disk defragmentation on SSD system drives. Because SSDs perform extremely well on random read operations, defragmenting files isn’t helpful enough to warrant the added disk writing defragmentation produces. The FAQ section below has some additional details.
Be default, Windows 7 will disable Superfetch, ReadyBoost, as well as boot and application launch prefetching on SSDs with good random read, random write and flush performance. These technologies were all designed to improve performance on traditional HDDs, where random read performance could easily be a major bottleneck. See the FAQ section below for more details.
Since SSDs tend to perform at their best when the operating system’s partitions are created with the SSD’s alignment needs in mind, all of the partition-creating tools in Windows 7 place newly created partitions with the appropriate alignment.
Frequently Asked Questions
Before addressing some frequently asked questions, we’d like to remind everyone that we believe the future of SSDs in mobile and desktop PCs (as well as enterprise servers) looks very bright to us. SSDs can deliver on the promise of improved performance, more consistent responsiveness, increased battery life, superior ruggedness, quicker startup times, and noise and vibration reductions. With prices steadily dropping and quality on the rise, we expect more and more PCs to be sold with SSDs in place of traditional rotating HDDs. With that in mind, they focused an appropriate amount of their engineering efforts towards insuring Windows 7 users have great experiences on SSDs.
Will Windows 7 support Trim?
Yes. See the above section for details.
Will disk defragmentation be disabled by default on SSDs?
Yes. The automatic scheduling of defragmentation will exclude partitions on devices that declare themselves as SSDs. Additionally, if the system disk has random read performance characteristics above the threshold of 8 MB/sec, then it too will be excluded. The threshold was determined by internal analysis.
The random read threshold test was added to the final product to address the fact that few SSDs on the market today properly identify themselves as SSDs. 8 MB/sec is a relatively conservative rate. While none of their tested HDDs could approach 8 MB/sec, all of their tested SSDs exceeded that threshold. SSD performance ranged between 11 MB/sec and 130 MB/sec. Of the 182 HDDs tested, only 6 configurations managed to exceed 2 MB/sec on our random read test. The other 176 ranged between 0.8 MB/sec and 1.6 MB/sec.
Will Superfetch be disabled on SSDs?
Yes, for most systems with SSDs.
If the system disk is an SSD, and the SSD performs adequately on random reads and doesn’t have glaring performance issues with random writes or flushes, then Superfetch, boot prefetching, application launch prefetching, ReadyBoost and ReadDrive will all be disabled.
Initially, we had configured all of these features to be off on all SSDs, but we encountered sizable performance regressions on some systems. In root causing those regressions, we found that some first generation SSDs had severe enough random write and flush problems that ultimately lead to disk reads being blocked for long periods of time. With Superfetch and other prefetching re-enabled, performance on key scenarios was markedly improved.
Is NTFS Compression of Files and Directories recommended on SSDs?
Compressing files help save space, but the effort of compressing and decompressing requires extra CPU cycles and therefore power on mobile systems. That said, for infrequently modified directories and files, compression is a fine way to conserve valuable SSD space and can be a good tradeoff if space is truly a premium.
We do not, however, recommend compressing files or directories that will be written to with great frequency. Your Documents directory and files are likely to be fine, but temporary internet directories or mail folder directories aren’t such a good idea because they get large number of file writes in bursts.
Does the Windows Search Indexer operate differently on SSDs?
Is Bitlocker’s encryption process optimized to work on SSDs?
Yes, on NTFS. When Bitlocker is first configured on a partition, the entire partition is read, encrypted and written back out. As this is done, the NTFS file system will issue Trim commands to help the SSD optimize its behavior.
We do encourage users concerned about their data privacy and protection to enable Bitlocker on their drives, including SSDs.
Does Media Center do anything special when configured on SSDs?
No. While SSDs do have advantages over traditional HDDs, SSDs are more costly per GB than their HDD counterparts. For most users, a HDD optimized for media recording is a better choice, as media recording and playback workloads are largely sequential in nature.
Does Write Caching make sense on SSDs and does Windows 7 do anything special if an SSD supports write caching?
Some SSD manufacturers including RAM in their devices for more than just their control logic; they are mimicking the behavior of traditional disks by caching writes, and possibly reads. For devices that do cache writes in volatile memory, Windows 7 expects flush commands and write-ordering to be preserved to at least the same degree as traditional rotating disks. Additionally, Windows 7 expects user settings that disable write caching to be honored by write caching SSDs just as they are on traditional disks.
Do RAID configurations make sense with SSDs?
Yes. The reliability and performance benefits one can obtain via HDD RAID configurations can be had with SSD RAID configurations. (Please note - SSD RAID Arrays cannot user TRIM at present even if each drive alone can)
Should the pagefile be placed on SSDs?
Yes. Most pagefile operations are small random reads or larger sequential writes, both of which are types of operations that SSDs handle well.
In looking at telemetry data from thousands of traces and focusing on pagefile reads and writes, we find that
In fact, given typical pagefile reference patterns and the favorable performance characteristics SSDs have on those patterns, there are few files better than the pagefile to place on an SSD.
Are there any concerns regarding the Hibernate file and SSDs?
No, hiberfile.sys is written to and read from sequentially and in large chunks, and thus can be placed on either HDDs or SSDs.
What Windows Experience Index changes were made to address SSD performance characteristics?
In Windows 7, there are new random read, random write and flush assessments. Better SSDs can score above 6.5 all the way to 7.9. To be included in that range, an SSD has to have outstanding random read rates and be resilient to flush and random write workloads.
In the Beta timeframe of Windows 7, there was a capping of scores at 1.9, 2.9 or the like if a disk (SSD or HDD) didn’t perform adequately when confronted with their random write and flush assessments. Feedback on this was fairly consistent, with most feeling the level of capping to be excessive. As a result, they now simply restrict SSDs with performance issues from joining the newly added 6.0+ and 7.0+ ranges. SSDs that are not solid performers across all assessments effectively get scored in a manner similar to what they would have been in Windows Vista, gaining no Win7 boost for great random read performance.
Finally we can move on to the main focus of this review which is Kingston's SSDNow V+ 128GB Performance ATA-2 Solid State Disk.
Sturdily packaged in a small box barely larger than the installation CD retailers will be thankful for the move away from huge boxes for what are in effect small components. Labelling is extensive on the packaging and anyone picking up a unit for inspection in their local PC store will find everything they need to know listed for them.
We received a full retail kit that included cables, rails and even an enclosure to turn the drive into a nifty external USB 2.0 drive in a 2.5" form factor. Doing so will, however, reduce the performance drastically due to USB 2.0 bottlenecks but could make a low power alternative to a traditional portable HDD drive. The installation CD includes tools for cloning disk partitions and will enable the easy transfer of data from HDD to SSD for upgraders.
The drive itself is made from strong plastic and should be very strong (see YouTube video below for just how strong).
Seeing the drive from behind shows just how small it is compared to a normal HDD (the connectors take up the entire edge of the drive. Four torx screws hold the case closed and we didn't have the right size bit to open it so we cannot show you the chips and controller inside.
This is an amusing video showing just how tough Kingston's new V and V+ Solid State Disks are. Just don't try this at home - it's not covered by the 3 year warranty.
note: Some of the listed capacity is used for formatting and other functions and
thus is not available for data storage.
We will be testing using the V+, a high performance HDD (Samsung's 7200rpm 1TB SATA-2 drive), a high performance replacement SSD aimed at the NetBook market and a low end SSD that comes as standard with NetBooks. We'll also show the results for using Windows file compression with the most basic SSD to simulate users who just can't afford to upgrade and would like to know what effect compression has on performance. Next week we will be testing Kingston's SDNow V 64GB entry level drive which is the first sub £100 SSD to be available to the public and it will be interesting to see how existing price/performance points are shaken up.
HD Tune Pro 3.5 is our standard benchmark for storage devices and has served us well since we moved from HD-Tach. It allows comprehensive read and write tests that stress both SSD and HDDs as well as optical and flash drives.
Straight away we can see the V+ being twice as fast or more than the Samsung HDD and leaving the NetBook SSDs for dust. It's worth noting also that while the minimum and maximum performance of the HDD varies considerably, that of the V+ is much more consistent. The SaberTooth does well at the same price point as the Samsung HDD but is restricted to 32GB of capacity compared to the whopping 1000GB of the HDD.
Looking at write speeds shows how the V+ has double the average and triple the minimum speed of the conventional HDD. The traditional weakness of SSDs has been slow write speeds and it's a testament to the quality of the Toshiba controller Kingston are using in their updated V+ drives that write speeds are so high. Burst rates are really only theoretical and depend more on cache than any sustainable performance so the first three indicators are key here.
Now time to hang on to your hats as we demonstrate the real reason why we have been champions of SSDs for years. HDDs are limited by having to physically move heads over spinning magnetic media whereas SSDs have no such limits on the number of operations they can complete in one second. For small block sizes the HDD heads have to move back and forth furiously clicking away and spend far more time traveling than they do reading and/or writing data. This allows the V+ to be over 100 times faster than the Samsung HDD for such operations and even the ultra cheap SSDs that come with NetBooks as standard can easily beat the high end HDD.
HDDs are limited in their seek times by moving heads as per the previous benchmark and here we can see typical access times. Without any moving parts the V+ is up to 100 times faster at accessing data. This is not the case with all SSDs though as we can see the budget ones that use low quality memory and cheap controllers are actually worse than the Samsung HDD.
At the end of the day speed is king and when accessing lots of little files there is a big slowdown for every drive but the HDD is affected so badly that it is beaten by all the contenders. On the more representative Random access scale, the V+ is almost 10 times faster than the HDD. This is also the closest indicator of how fast windows will boot with a particular drive as the types of files loaded during booting are of this mixture. It does not mean that windows will boot up 10 times faster since other bottlenecks such as the CPU will affect load times.
This graph can be a little misleading as the SaberTooth and Phison SSDs were tested on an ASUS Eee PC 901 and in fact, when we compensate for the fact we are using an i7-870 system and not an Intel Atom one, the CPU utilization for all the drives is around the 1% mark showing a level of efficiency that is very close to optimal for all test participants.
AS SSD is a benchmark designed exclusively for SSDs but handles HDDs just as well. It also gives a nice graphical summary of results so readers don't have to look at boring derived Excel charts.
On the left is the Kingston V+ and on the right is the Samsung. You can click on either one to launch a higher resolution picture in another window if you're having trouble making out the detail in these shots. The scoring system may seem a little arbitrary but supports the test results we have seen so far.
Everest is a very comprehensive benchmarking suite that covers all aspects of system performance in much the same was as SiSoft Sandra does. Here we are using the Storage tests.
Performance for a HDD varies depending on which part of the platter is being accessed. If you visualize the spinning magnetic disk you can see that close to the spindle the surface is spinning slowly and close to the edge it is moving fastest. Since data density is constant it can be seen that data can be read or written to faster at the start of the disk. SSDs have no moving parts and as can be seen from the above results, are not affected by which part of the disk is being accessed. The buffered results again represent the benefits of cache and interface properties so should not be taken too seriously - the important results are the first four.
We knew that the Kingston V+ 128GB SSD was going to beat the Samsung 1TB HDD but would it be enough to justify double the price and almost 40 times the cost per Gigabyte? In our opinion, the answer is most definitely yes, not because of the benchmarks but rather the experience of using an SSD instead of HDD and having Windows 7 boot up in less than half the time and even more, seeing games and applications load in the blink of an eye because SSDs can be a hundred times faster than HDDs when loading numerous small files.
SSDs have a long way to go before being cheaper than HDDs in terms of cost per GB but this should not put people off purchasing as the best combination today is an SSD as the boot drive containing the Operating System and a conventional HDD of whatever size is needed for storage/archiving data that is less frequently accessed.
Kingston have really been a key player in pushing forward the adoption of SSDs, partly because of their background in memory manufacturing but also in an effort to drive innovation - something which has seen them recently announce record revenues during a time of recession. Intel may have led the way with their X-25M SSD but have rested on their laurels to allow others like Kingston to take the price and performance lead. Next week we will be taking a look at Kingston's V series SSD drive which is aimed at the entry level consumer and priced at below £100 and we will see what performance is like at the budget end of the SSD market.
For now the only competitors able to beat Kingston's V+ in terms of performance are the top end drives from Intel and OCZ etc. which are only slightly faster in benchmarks (not at all noticeably faster in real world experience) and cost twice as much. That makes the Kingston SSDNow V+ series of SSD drives the obvious choice for a performance SSD purchase.
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