|Intel Smart Response Technology|
|Reviews - Featured Reviews: Storage|
|Written by David Ramsey|
|Tuesday, 10 May 2011|
Intel Smart Response Technology
Well, we're almost halfway through 2011, and guess what? Although SSDs have come down in price, they're still pretty darn expensive. If you're a regular Benchmark Reviews reader, you've seen our numerous SSD reviews and know that replacing your hard disk with an SSD is the single biggest performance improvement you can make to your system. But with 256G SSDs going for between $427 and $584 on Newegg, versus dozens of terabyte drives for less than $75.00, most people choose the latter. But Intel's new Smart Response Technology, available initially on Z68 Express motherboards, promises to bring much of that speedy SSD performance to users via a small SSD used as a cache for the main hard drive.
The concept of caching isn't new: the computer industry has had the problem of "cheap slow storage" vs. "fast expensive storage" since the ENIAC days. Modern processors have up to three levels of increasingly faster cache memory on-chip in an attempt to minimize the accesses required to relatively slow motherboard memory.
Even using flash memory and SSDs as caching isn't new. Some models of Seagate's "Momentus" hard drives are hybrid drives with up to 4GB of onboard flash memory. Silverstone's "HDD Boost" is a bracket combining mounts for a hard drive and SSD with a small onboard processor that uses the SSD as a cache for the hard drive. While both products provided performance improvements, they weren't as dramatic as you might expect.
Like these other products, Intel's "Smart Response Technology" is an SSD caching scheme: you pair a smallish SSD (20G to 64G, or up to a 64G partition on a larger SSD) with a hard drive to to accelerate access to the files on the hard disk. This does require that you configure your SATA ports to RAID mode, and the SSD should be ideally be much faster than your hard drive (most are, of course, but an old first-generation SSD paired with a 600G Western Digital VelociRaptor drive won't give you as much of a boost as you'd expect.)
Your SATA controller must be set to RAID mode (rather than AHCI or IDE modes) for Smart Response Technology to work, so this is best done as part of installing a new Windows system, since setting your SATA controller to RAID mode once you've already installed Windows will generally result in a non-booting system. Once you've connected your hard drive and SSD, you use Intel's Rapid Storage Technology utility to configure what they call "Acceleration":
If you don't see the "Acceleration" tab, it probably means your SATA controller isn't in RAID mode. But if you do, suddenly all those tiny SSDs I wondered about (what use were they?) become useful! The Intel configuration utility will automatically detect the SSD and offer to use it as a "cache device", after warning you that anything on it will be erased. You can then select the drive you want to be "accelerated" (you can only select one):
You'll notice in the volume selection dialog that you can choose "Enhanced Mode" or "Maximized mode". The difference is that Enhanced Mode is write-through (information is written directly to the hard disk), while Maximized mode caches writes as well as reads. I'd recommend staying with Enhanced Mode for most people, since Maximized Mode risks data loss or disk corruption in the case of a crash, power loss, or other unexpected problem. I ran my tests using Enhanced mode, but using Intel's application, you can turn acceleration on, off, or switch between Enhanced and Maximized modes at any time without rebooting.
Intel says the caching algorithms are quite intelligent: for example, during a virus scan, Smart Response Technology won't try to cache all the files being scanned.
For these tests I used an ASUS P8Z68-V Pro motherboard with a Western Digital WD7500 750G hard disk as the primary drive, and an Intel "Larson Creek" 311 Solid State Drive SSDSA2VP020G2E 20G SSD for the caching drive. Intel bills this new SSD as the perfect cache devices for Smart Response Technology. I used PCMark Vantage's HDD test as a synthetic benchmark, and timed Windows boot times using the free Boot Timer utility, and shutdown times (time from pressing the "Shut Down" button until the computer switches off). Each test was run five times, the first result discarded, and the last four averaged. Timed results are rounded to the nearest second.
The results of these brief tests are impressive: a huge increase in synthetic benchmark scores as well as a dramatic decrease in Windows boot times. Windows shutdown times didn't improve much on this test, though.
But what does this mean in the real world? That's harder to quantify: you won't see an improvement unless something's in the cache, and nothing will get put into the cache until it's referenced at least once. So the first time you load that giant image in Photoshop, it's not going to be any faster since it'll have to be read from the hard disk. But as you continue working with it, successive accesses (especially to Photoshop's own internal cache) will be much faster.
The size of your SSD will also affect performance. If you come back to that Photoshop image the same afternoon, it'll probably load very quickly. After a day or two though, it'll likely be flushed out of the SSD cache drive by other data, but the larger your SSD is, the more data it will hold for longer periods of time. I suspect the seemingly arbitrary 64G cache size limitation was a tradeoff based on the size and speed of access to in-memory data structures used to reference and prioritize the cached data...but that's just a guess.
The thing to keep in mind is that running your system on a single, large SSD makes it faster all the time, whereas Smart Response Technology can only make things faster if the data you need is already on the cache SSD. This guarantees that the first time you need the data, you'll get it at hard disk speeds rather than SSD speeds.
But within that limitation, the fine-tuning of the algorithms that manage cached data make all the difference, and based on what I've seen so far, Intel's doing a good job of things like caching Windows code and data that makes the whole system seem noticeably "snappier". This is where they get the "Smart" in "Smart Response Technology": rather than treating all data equally, Intel's driver has a fair bit of intelligence about what to cache and how long to keep it in the cache, and perhaps more importantly, what not to cache, as in the virus scan example mentioned above. As a programmer for some decades, I've seen that slowdowns in performance are much more noticeable than speedups in performance. After your configure your Intel Smart Response Technology system, you'll notice the system seems somewhat faster. If you shut it down after running with it for a few days, it will feel as though your entire computer is mired in thick mud.
One caveat: once an SSD is configured for use as a Smart Response Technology cache, you can't simply turn off caching, remove the SSD, and use it for something else. After you disable caching, make sure you click on the "Reset to available" link under "SSD Configuration" in the Intel Rapid Storage Technology utility. If you skip this step, you won't be able to create a volume on the SSD using Windows' Disk Management, although you can use a Linux utility like the Gnome Partition Editor (gparted) to do so.
64G SSDs (the largest Smart Response Technology will use) range from $119 to $179 on Newegg.com. That's still not cheap, but it is much less expensive than the 128G or 256G SSD you'd need otherwise. Based on my admittedly limited experience with it, I think this product will be a real winner.
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