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Intel's X25-V solid-state drive on its own and in RAID


A value-oriented SSD gets thrown to the wolves
— 11:48 PM on May 10, 2010

The rise of solid-state drives has been one of the most exciting developments in PC hardware over the last few years. With essentially instantaneous seek times, SSDs can access data an order of magnitude quicker than even the most exotic high-RPM hard drives. With no moving parts, SSDs are impervious to mechanical failure, able to withstand shocks that would destroy traditional hard drives. Their silicon roots also make SSDs completely silent and quite power-efficient compared to their mechanized brethren. And the prospects for SSDs look even brighter when one considers the performance potential of what are essentially parallel arrays of flash memory chips.

Really, it's no wonder many of us are eyeing SSDs for our desktops and notebooks. In a high-performance PC, an SSD is perfect for an OS and applications drive, augmented by a larger pool of mechanical storage. Such a configuration offers excellent performance for the data you want to access quickly and loads of capacity for the rest. Those who opt for a low-power mechanical hard drive to serve as secondary storage will be treated to a virtually silent setup, as well.

Few notebooks can accommodate multiple hard drives, but rugged shock tolerance and the ability to prolong battery life makes SSDs particularly tempting for portables. Solid-state drives have an even greater performance advantage over the 2.5" mechanical drives typically found in notebooks, which are considerably slower than full-grown 3.5" desktop models.

Of course, all this awesomeness comes at a cost—quite a high one, in fact. SSD prices have plunged dramatically in recent years, but drives are still far from cheap, especially when one considers the cost per gigabyte.

The relatively high price of solid-state storage is certainly not lost on Intel. At the Consumer Electronics Show back in January, the company said its SSD plans for 2010 would focus more on driving down costs and lowering prices than on increasing performance. Indeed, Intel kicked off the year with its very first value-oriented SSD, the X25-V 40GB. Low-cost, low-capacity SSDs have existed for some time, of course, but the X25-V marks Intel's first foray into a market that's sure to receive an increasing amount of attention. The drive launched at $130 and has already dropped to just $115 online.


Compared to a mechanical drive, 40GB for $115 may not seem like much of a value. But this 40GB isn't saddled with the baggage associated with spinning platters; it's spread across 34-nm flash memory chips hooked up to the same controller Intel uses in its standard-setting X25-M SSDs. Controller architectures tend to dictate SSD performance, and Intel's design has already proven itself to be more robust than other solutions on the market.

The X25-V's relatively low asking price opens the door to folks who might otherwise have been unable to afford a higher-capacity SSD. Given the fact that the X25-V's cost per gigabyte is competitive with most other SSDs, enterprising users can also combine multiple drives in a RAID 0 array without exceeding the cost of single drives that offer similar capacities. With zero chance of mechanical failure, striping is a lot safer with SSDs than it is with mechanical hard drives.

Naturally, we had to test the X25-V for ourselves. And then Intel sent two, so we've run the X25-V through our new gauntlet of storage tests both on its own and in a striped RAID 0 array. Read on to see how Intel's value SSD fared.

X25-M/2?
As you may have gathered, the X25-V looks to be a stripped down version of the X25-M, with the same storage controller and the same 34-nm flash memory chips. Because the X25-V only has five flash chips onboard, it can only exploit half of the controller's ten memory channels. That translates to lower performance ratings, as summarized in the chart below.

X25-M G2 X25-V
Controller Intel PC29AS21BA0 Intel PC29AS21BA0
Flash fabrication process 34nm 34nm
Capacity 80, 160GB 40GB
Cache 32MB 32MB
Max sequential reads 250MB/s 170MB/s
Max sequential writes 70MB/s (80GB)
100MB/s (160GB)
35MB/s
Read latency 65 µs 65 µs
Write latency 85 µs 110 µs
Max 4KB read IOPS 35,000 25,000
Max 4KB write IOPS 6,600 (80GB)
8,600 (160GB)
2,500
Active power consumption 150 mW 150 mW
Idle power consumption 75 mW 75 mW
Warranty length Three years Three years

The X25-V's maximum sustained read speed is only 32% slower than the X25-M's, but Intel's value SSD pulls up quite a bit shorter with writes. The X25-V's 35MB/s sustained write speed rating is half what Intel quotes for the 80GB X25-M and a little more than a third the speed of a 160GB drive. Plus, 35MB/s just sounds, well, sluggish.

In addition to slower sustained transfer rates, the X25-V carries lower performance ratings for random 4KB reads and writes. Again, the drive is much further behind the X25-M with writes than it is with reads. The X25-V also has a longer write latency than the X25-M, although read latencies are equal between the two.

I'm going to go out on a limb here and bet that the power consumption figures Intel has published for the X25-V aren't entirely accurate. With fewer flash chips than the X25-M, I'd expect the V to pull less power both at idle and under load. Intel's datasheets suggest differently, but we'll test power consumption for ourselves in a moment.


The X25-V may not measure up to the X25-M's performance levels, but it still inherits quite a few perks from the elder members of the G2 family. Like Intel's other second-gen drives, the X25-V has built-in garbage-collection and wear-leveling algorithms, native support for the TRIM command built into Windows 7, and an SSD Optimizer application capable of clearing erased flash pages in Windows XP and Vista. Some combination of these measures is necessary to keep an SSD operating in top shape. The Optimizer can be set to run on a schedule, which is much more convenient than having to invoke the process manually. However, Intel notes that system use should be minimized while the Optimizer is running. The application's support docs suggest an Optimizer pass should only take a few minutes, which should be easy enough for most users to sit through or schedule around.


Intel packs the X25-V into the same 2.5", 9.5-mm mobile hard drive form factor being used by just about every other SSD maker. The drive's metal casing actually measures closer to 6.5 mm thick, but a black spacer on the top of the drive brings it up to 9.5 mm. For those looking to install the X25-V in a desktop enclosure, a 3.5" bay adapter is included in the retail box. 2.5" drive bays have slowly started creeping into enthusiast-oriented cases, but they're few and far enough between to make the adapter a nice addition to the overall package.

Three years of warranty coverage is the de facto standard for consumer-grade hard drives, and the X25-V doesn't budge from that mark. The X25-M is also covered for three years, as are most of the SSDs we've reviewed recently.