Depending on who you believe, the solid-state storage revolution is on the horizon, just over it, a few years away, or already upon us. Analysts, journalists, and forum fanboys can’t seem to come to an agreement on exactly where we are in the process. One thing seems certain, though: At least for some markets, it’s not a question of if solid-state storage will take over from traditional mechanical hard drives, but when.
Of course, the mechanical hard drive is by no means dead. The torrid pace of platter development is still yielding impressive increases in performance and capacity. But as the price of solid-state alternatives tumbles, SSDs are sure to carve out a niche in the mobile space, where their superior shock tolerance and low power consumption are more important than storage capacity. Solid-state drives won’t just make their way into notebooks, though. The near-instantaneous seek time of flash memory offers tantalizing performance potential for any workload dominated by random I/O requests. SSDs aren’t nearly as impressive when it comes to sequential transfers, but they’re getting faster on that front, too, making them interesting options for high-end desktops, workstations, and servers.
So solid-state drives are going to be big. Very big. And everyone wants a slice of the pie. It’s no wonder, then, that industry giant Intel is eager to get in on the action. The company is in a rather unique position to serve the SSD market, too, with expertise not only in the chip manufacturing capability essential to populating a drive with memory, but also in the storage controller design that largely dictates performance.
Intel formally detailed its solid-state drive plans at IDF just a couple of weeks ago, revealing not just a single drive, but an entire collection of products that will trickle out in the coming months. The first of these SSDs to hit the market will be the X25-M, which boasts an impressive 250MB/s sustained read rate, a 70MB/s sustained write rate, 80GB of storage capacity in a 2.5″ form factor, and support for Native Command Queuing. Read on to see how this drive stacks up against a mix of solid-state and mechanical alternatives through our exhaustive suite of performance, noise level, and power consumption tests.
The X25-M is based on multi-level cell (MLC) NAND flash memorya cheaper alternative to the single-level cell (SLC) memory used in some flash drives. Cheaper is relative, of course; we’re still talking about SSDs.
MLC memory is characterized by relatively slow write speeds, and the X25-M’s 70MB/s sustained write rate lives up to MLC’s reptuation. Calling 70MB/s relatively slow seems almost comical given that few 7,200-RPM notebook hard drives can match that speed. However, the Intel drive’s whopping 250MB/s sustained read rate quickly puts things into perspective. That’s more than twice the sustained read throughput of the latest desktop WD VelociRaptor and leagues ahead of the fastest mobile competition. (For comparison, the SLC-based 64GB Samsung FlashSSD we reviewed not long ago is rated for 100MB/s sustained reads and 80MB/s writes.) Finally, we have a drive capable of exploiting its 300MB/s Serial ATA interface.
While we’re embarassing the VelociRaptor, we should note that the X25-M has a read latency of just 85 microseconds. That’s 0.085 milliseconds, if we convert to units more commonly associated with hard drives. For comparison, the random access time of the VelociRaptor is 7.4 millisecondsa difference of two orders of magnitude.
The X25-M owes its low latency to the zippy access times inherent to flash memory. 20 flash chips can be found on the X25-M: 10 on the top of the drive’s circuit board and 10 on the back, for a total of 80GB. Intel fabricates these chips itself using a 55nm process, although rival flash giant Samsung amusingly makes an appearance with a K4S281632I-UC60 memory chip that weighs in at 16MB. Way to throw Samsung a few dollars (or more likely, pennies) for every SSD sale you beat them to, Intel.
As one might expect from a company with a long history of developing core-logic chipsets, the X25-M’s storage controller is an Intel designand a smart one at that, with support for, ahem, SMART monitoring. More interestingly, the controller supports Native Command Queuing (NCQ)a new trick for SSDs. NCQ was developed to reduce the performance impact of mechanical latency found in traditional hard drives, so it’s might seem like an odd choice for a solid-state drive with no mechanical parts. According to Intel, its SSDs are so fast that NCQ helps to compensate for latency encountered in the host PC. Even today’s fastest systems take some time (time is relative in the microsecond world of the SSD) between when a request is completed and another one is issued. Queuing up multiple requests can keep a solid-state drive busy during this downtime, and the X25-M is capable of stacking requests 32 deep.
So the X25-M shouldn’t be short on performance, but what about longevity? MLC-based flash memory cells are limited to 10,000 write-erase cycles, giving solid-state drives a finite lifespan. When estimating the operating life of their drives, other SSD makers generally rely on a basic formula to calculate the number of cycles used:
Cycles = (Host writes) / (Drive capacity)
Intel says this formula oversimplifies the issue, and that two other factors must be considered. The first of these variables is write amplification, which refers to the amount of data actually written to a drive for a given write request. Intel gives an example in which a host system generates a 4KB write request that, thanks to a drive’s 128KB erase block size, actually incurs a 128KB NAND write. Dividing the NAND write size by the request size yields the amplification factor, which is 32 in this case. Intel says the X25-M’s write-amplification factor is extremely low at 1.1, while “traditional” SSDs have much higher amplification factor of 20.
The efficiency of wear-leveling algorithms also has a hand in determining an SSD’s lifespan. If a drive is going to shuffle bits around to avoid bad cells and more efficiently use those available, it must do so without wasting precious write-erase cycles. Intel estimates the X25-M’s wear-leveling efficiency factor at less than 1.1, claiming that traditional SSDs have an efficiency factor of 3.
Taking write-amplification and wear-leveling efficiency into account, Intel says the correct formula for cycling is as follows:
Cycles = (Host writes) * (Write amplification factor) * (Wear leveling factor) / (Drive capacity)
Using a write-amplification factor of 1.1 and a wear-leveling efficiency factor of 1.1, 20GB of write-erase per day for five years should consume only about 550 cycles on an 80GB X25-M. Using “traditional” SSD technology with an amplification factor of 20 and an efficiency factor of 3, the same write-erase load would use over 27,000 cycles. That’s a huge difference, and to be fair, it’s one that relies on values provided by Intel that aren’t entirely consistent. Another Intel presentation from IDF estimates that “mediocre” SSDs have a write-amplification factor of 10 and a wear-leveling efficiency factor of 5, resulting in just under 23,000 cycles for our 20GB of write-erase per day example. That presentation also pegs the X25-M’s efficiency factor at 1.04 rather than 1.1. We can’t easily test a drive’s lifespan ourselves, but we did ask Samsung for the write-amplification and wear-leveling efficiency factor values for its SSDs. Samsung hasn’t responded yet, though.
If you don’t want to crunch through the math, Intel estimates that the 80GB X25-M will last for five years with “much greater than” 100GB of write-erase per day. That’s a relatively long time for much more data than most folks are likely to write or erase on a daily basis.
Actual drive lifespans aside, Intel rates the X25-M’s Mean Time Between Failures (MTBF) at 1.2 million hours. That’s competitive with the MTBF rating of other MLC-based flash drives and equivalent to common MTBF ratings for enterprise-class mechanical hard drives.
Rather than banking on a single SSD, Intel has prepared a full lineup of solid-state drives with multiple form factors, capacities, and memory types. The X25-M will come first, with 80GB models in mass production this month, followed by 160GB derivatives early next year. Intel will also offer 1.8″ versions of this drive destined for thin-and-light notebooks and, dare we dream, netbooks as well.
Lest one market segment go without unwarranted Mountain Dew branding, Intel has an Extreme SSD in the works, too. The X25-E will only be available in 2.5″ form factors with capacity points at 32 and 64GB. This SLC-based drive maintains the X25-M’s 250MB/s sustained read rate, but boosts writes up to 170MB/s and drops read latency to 75 microseconds. The Extreme also features an MTBF rating of two million hours and enjoys SLC memory’s 100,000 write-erase cycle tolerance, making it even more attractive for enterprise environments. 32GB versions of the X25-E should enter production in the next three months, followed by 64GB flavors next year.
The X25-E certainly won’t be cheapSLC-based drives rarely arebut we don’t yet know exactly how much it will cost. Intel has, however, confirmed that the 80GB X25-M will sell for $595 in 1,000-unit quantities. Drives will ship to the channel and major PC builders this week, and will either be sold on their own or installed in pre-built systems. We’ve also heard word that Intel partners may sell the company’s SSDs under their own names. That wouldn’t be surprising considering that we’ve already seen OCZ repackaging Samsung’s FlashSSD drives.
We’ll be comparing the performance of the X25-M with that of a slew of direct and indirect competitors, including solid-state drives from Samsung and Super Talent, a handful of 2.5 mobile drives from Seagate and Western Digital, and a collection of the fastest 3.5 desktop drives on the market. These drives can differ when it comes to external transfer rates, capacities, cache sizes, and (for the mechanical ones) spindle speeds, and platter densities, all of which can have an impact on performance. Keep in mind the following differences as we move through our benchmarks:
Caviar SE16 (640GB)
On the solid-state front, the X25-M is joined by Samsung’s FlashSSD and Super Talent’s MasterDrive MX. The FlashSSD is an SLC-based drive rated for 100MB/s sustained reads and 80MB/s writes. The MasterDrive uses Super Talent’s original firmware and is rated for 120MB/s reads and 40MB/s writes. Pay particular attention to how these three drives stack up against each other.
To give the X25-M some additional 2.5″ competition, we’ve included the latest 7,200-RPM mobile drives from Seagate and Western Digital. Western Digital’s 5,400-RPM Scorpio Blue is also in the mix to illustrate how the SSDs look against a slower spindle speed.
Our 3.5″ drives can’t squeeze into systems that can easily accommodate the 2.5″ X25-M, but we’ve included a collection of the latest desktop models because Intel is eager to push solid-state drives for servers, workstations, and high-end desktops. It will be interesting to see how the X25-M fares against the VelociRaptor, which is the fastest mechanical SATA drive on the market.
Performance data from such a daunting collection of drives can make our bar graphs a little hard to read, so we’ve colored the bars by manufacturer, with the X25-M appearing in bright blue.
Our testing methods
All tests were run three times, and their results were averaged, using the following test system.
|Processor||Pentium 4 Extreme Edition 3.4GHz|
|System bus||800MHz (200MHz quad-pumped)|
|Motherboard||Asus P5WD2 Premium|
|North bridge||Intel 955X MCH|
|South bridge||Intel ICH7R|
|Chipset drivers||Chipset 220.127.116.113
|Memory size||1GB (2 DIMMs)|
|Memory type||Micron DDR2 SDRAM at 533MHz|
|CAS latency (CL)||3|
|RAS to CAS delay (tRCD)||3|
|RAS precharge (tRP)||3|
|Cycle time (tRAS)||8|
|Graphics||Radeon X700 Pro 256MB with CATALYST 5.7 drivers|
Seagate Barracuda 7200.11 1TB SATA
Samsung Spinpoint F1 1TB SATA
Hitachi Deskstar 7K1000 1TB SATA
Western Digital VelociRaptor 300GB SATA
Western Digital Caviar Black 1TB SATA
Samsung FlashSSD 64GB SATA
|OS||Windows XP Professional|
|OS updates||Service Pack 2|
Thanks to NCIX for getting us the Deskstar 7K1000 and Spinpoint F1.
Our test system was powered by OCZ PowerStream power supply units.
We used the following versions of our test applications:
- WorldBench 5.0
- Intel IOMeter v2004.07.30
- Xbit Labs File Copy Test v1.0 beta 13
- TCD Labs HD Tach v3.01
- Far Cry v1.3
- DOOM 3
- Intel iPEAK Storage Performance Toolkit 3.0
The test systems’ Windows desktop was set at 1280×1024 in 32-bit color at an 85Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.
All 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.
WorldBench uses scripting to step through a series of tasks in common Windows applications. It then produces an overall score. WorldBench also spits out individual results for its component application tests, allowing us to compare performance in each. We’ll look at the overall score, and then we’ll show individual application results.
The X25-M gets off to a good start, scoring higher in WorldBench than any other hard drive we’ve tested. Samsung’s FlashSSD is only one point off the pace, followed by a collection of 3.5″ desktop drives.
Multimedia editing and encoding
Windows Media Encoder
VideoWave Movie Creator
In three of four WorldBench multimedia editing and encoding tests, the X25-M turns in the quickest completion times of the lot. With the exception of the MasterDrive, however, all of the contenders we’ve assembled are pretty close.
The X25-M ties for the lead in WorldBench’s Photoshop test and is right in the thick of things in the ACDSee test. Scores are still relatively close across the board, though.
Multitasking and office applications
Mozilla and Windows Media Encoder
Completion times for WorldBench’s office and multitasking tests don’t vary much from one drive to the next, but the Intel SSD still finds itself at, or close to, the front of the pack.
Of all the WorldBench application tests, Nero and WinZip are the most demanding of the storage subsystem. The X25-M comes out on top in both tests, just edging out the Samsung FlashSSD, ahead of the fastest 3.5″ SATA drives on the market.
To test system boot and game level load times, we busted out our trusty stopwatch.
The X25-M’s system boot time isn’t particularly impressiveit’s actually slower than that of our 5,400-RPM Scorpio Blue. However, Intel’s first solid-state drive comes back in a big way in our level load tests, which have it leading the field, a hair ahead of the FlashSSD. Note just how big a lead the X25-M has over not only our 3.5″ contenders, but also the fastest 2.5″ mechanical hard drive of the lot, the Scorpio Black.
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. File copying is tested twice: once with the source and target on the same partition, and once with the target on a separate partition. Scores are presented in MB/s.
To make things easier to read, we’ve separated our FC-Test results into individual graphs for each test pattern. We’ll tackle file creation performance first.
MLC-based flash drives are notorious for their relatively slow write performance, and the X25-M isn’t an exception to that rule. The Intel SSD isn’t nearly as slow as the MasterDrive here, and it’s surprisingly faster than the SLC-based FlashSSD with one workload. Overall, however, the X25-M’s file creation speeds can’t keep up with even the 5,400-RPM Scorpio Blue.
What the X25-M lacks in sustained write performance it more than makes up when it comes time to read. The Intel drive easily outguns the rest of the pack here, enjoying a commanding lead with all five test patterns. Not even the desktop VelicoRaptor comes close.
Next, File Copy Test combines read and write tasks in some, er, copy tests.
Copy tests combine read and write operations, and it’s the X25-M’s slow write speeds that likely hinder it here. The Intel SSD actually fares pretty well with the Windows and Programs test patterns, which are made up of large numbers of small files. However, it’s not nearly as competitive with the ISO, MP3, and Install test patterns.
FC-Test’s second wave of copy tests involves copying files from one partition to another on the same drive.
Our partition copy results closely track with those of the standard copy test. The X25-M offers reasonable performance when copying large groups of small files, but it’s much slower with test patterns dominated by smaller numbers of larger files.
We’ve developed a series of disk-intensive multitasking tests to highlight the impact of seek times and command queuing on hard drive performance. You can get the low-down on these iPEAK-based tests here. The mean service time of each drive is reported in milliseconds, with lower values representing better performance.
The X25-M leads the field with iPEAK workloads that include a read-intensive Virtualdub import operation as a secondary task. Otherwise, the drive’s performance is mixed, and not nearly as consistent as that of the Samsung FlashSSD.
If we average all our iPEAK scores, the FlashSSD comes out ahead of the field with a mean service time of 0.81 milliseconds. The X25-M scores a second place finish with a mean service time average of 1.05 milliseconds0.26 milliseconds ahead of the VelociRaptor, which isn’t bad at all.
IOMeter presents a good test case for both seek times and command queuing.
This, ladies and gentlemen, is absolute domination. The X25-M thoroughly outclasses the competition here, wiping the floor with not only every mechanical hard drive in the field, but the other SSDs, as well.
IOMeter’s file server, workstation, and database test patterns are made up of a mix of read and write requests, so the X25-M’s ability to stay so far ahead of the competition is especially impressive there. The web server test pattern is made up exclusively of read requests, allowing the X25-M to achieve even higher transaction rates. Note that with the web server test pattern, the Intel SSD’s performance levels off after we hit 32 concurrent I/O requeststhe max depth of the drive’s Native Command Queueing implementation.
As one might expect, the X25-M is the class of the field when we look at IOMeter response times. All our SSDs have a huge advantage with the web server test pattern, but among them, the Intel drive is still the quickest.
We don’t usually see IOMeter CPU utilization scores higher than a few percent, but particularly with the web server test pattern, the X25-M consumes more cycles than its rivals. This is to be expected, of course, because the Intel SSD is pushing much higher transaction rates.
We tested HD Tach with the benchmark’s full variable zone size setting.
Although it doesn’t quite hit the 250MB/s sustained read rate Intel promises, the X25-M manages to post a blistering 229MB/s in HD Tach’s average read speed test. That gives the drive a huge lead over the fieldright up until we test its sustained write performance. Somewhat surprisingly, the X25-M’s average write speed eclipses its rated 70MB/s. However, that’s only fast enough to stay ahead of our 2.5″ mechanical drives, not quite quick enough to catch Samsung’s FlashSSD or the cream of the 3.5″ desktop crop.
The Intel SSD’s burst performance leads the field, but what’s more interesting is the fact that the MasterDrive and FlashSSD both fail to muster much more than 100MB/s in this test.
HD Tach doesn’t measure seek times down to the microsecond, so the X25-M will have to make do with tying the Samsung drive with a 0.1-millisecond random access time.
The X25-M’s CPU utilization is a little higher than the rest here, but keep in mind that HD Tach’s margin of error in this test is +/- 2%.
Noise levels were measured with an Extech 407727 Digital Sound Level meter 1″ from the side of the drives at idle and under an HD Tach seek load. Drives were run with the PCB facing up.
Without mechanical parts, our SSDs are entirely silent. Their 42.6-decibel reading here represents the noise generated by the rest of our test system.
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. Through the magic of Ohm’s Law, we were able to calculate the power draw from each voltage rail and add them together for the total power draw of the drive.
Those eager to pop the X25-M into a notebook will be happy to learn that the drive sips less than one watt at idle and only about one-and-a-half watts when seeking. While those results are impressive, Samsung’s FlashSSD consumes even less power. To be fair, though, the X25-M is an 80GB drive while the FlashSSD is only 64GB.
We had high hopes for Intel’s first solid-state drive. As a master fabricator, the company has the chip-making chops to churn out fast, power-efficient memory cells. More than a decade of core-logic chipset design also gives Intel the storage controller mojo necessary to craft a wicked-fast SSD architecture. The X25-M delivers on both fronts, with low power consumption that should make notebook users swoon and truly inspiring performance with some workloads.
Solid-state drives have an inherent power consumption advantage over their mechanical counterparts, so the energy efficiency isn’t much of a feat. What’s more impressive is the X25-M’s performance. Thanks to a 250MB/s sustained read rate and a smart Native Command Queuing implementation, Intel’s first SSD sets a new standard for MLC-based solid-state drives. Unfortunately, though, Intel can’t escape the relatively slow write speeds that plague MLC drives, and that results in a performance profile that’s decidedly mixed.
When the X25-M is good, it’s exceptional. The drive absolutely dominated our IOMeter workloads and ran away from the field in our sustained-read-speed drag race and in our real-world file read tests. The X25-M also posted speedy game level load times and a higher WorldBench overall score than any other drivesolid-state or mechanical.
Start to stress the Intel SSD’s relatively slow write rate, however, and things don’t look nearly as impressive. The X25-M excels with iPEAK multitasking workloads that are heavy on read requests, but not those that favor writes. Its real-world write speeds aren’t all that hot, either, with the Intel drive turning in particularly poor file creation speeds in FC-Test. Flash can be very fast indeed, but the slower write speed of MLC memory is still a weak link.
Price is another problem for solid-state drives, and with the 80GB X25-M slated to sell for just under $600 in 1,000-unit quantites, Intel’s first entry in the market won’t be cheap. At that price, the X-25M sits between budget MLC-based models and their more expensive SLC-based cousins, which seems about right to me. After all, the X25-M was often faster than Samsung’s SLC-based FlashSSD, which costs nearly $800 for only 64GB.
Obviously, SSDs still have a lousy cost per gigabyte when compared to their mechanical rivals. But there’s usually a premium to be paid for performance leadership, and if you measure value in IOMeter transactions per dollar, the X25-M is an absolute bargain. This SSD’s power efficiency, shock tolerance, and silent acoustic profile will probably appeal to other markets, as well. I have a feeling boutique PC builders are going to snap these up for their uber-high-end notebooks and even desktops.
Perhaps more impressive than what the X25-M offers today is what the drive fortells for the future. Intel has a very good SSD architecture on its hands right now, and we know it plans to follow up with more products based on both SLC and MLC designs. Meanwhile, the company intends to transition its flash memory to a 32nm process node. Taken together, these steps could well cement its position as a leader in solid-state storage, just as SSDs are set to carve out a larger share of the market.