Smart Response travels up Larson Creek
Virtu got its start on the H67 Express, so it's hardly unique to the Z68. However, Intel's Smart Response Technology will be exclusive to the new chipset, at least on the desktop. Smart Response is a purportedly intelligent caching technology that puts an SSD between the hard drive and operating system. The scheme uses logic built into the chipset's storage controller and drivers to populate a solid-state drive with frequently accessed data and incoming writes.
Smart Response is capable of caching writes immediately, but data must be read at least once to make it onto the SSD. Simply accessing a file won't cause it to be copied into the cache, though. Intel says Smart Response is intelligent enough to determine whether reads are linked to a virus scan, a large file-copy operation, or media streaming. Caching isn't a priority for those "one-touch" cases, and it might not offer any tangible performance benefits. Intel is keenly aware of the fact that mechanical hard drives can offer superior sequential throughput to some SSDs.
Rather than caching individual files, Smart Response works at the block level and uses locality to predict which data should be copied to the SSD. Contrary to what one might expect given the 4KB blocks common to SSDs, Smart Response will vary its block size based on the workload.
To enable Smart Response, the Z68's SATA controller must first be put into RAID mode. From there, one selects the hard drive to accelerate and how much of the SSD's capacity the cache will occupy. The cache needs at least 18GB and will only consume up to 64GB. You can use any SSD you'd like, though. If the drive is larger than the size of your Smart Response cache, the excess capacity can be formatted and used as a standard Windows partition.
The final step in the Smart Response process is deciding whether to run in maximized or enhanced mode. Enhanced mode is for paranoid types who want to avoid the potential for data loss in the event of a power failure. This mode doesn't cache any writes, and the user can move his hard drive to a new system without bringing the SSD in tow.
Write caching is available in maximized mode, but you're on the hook if the lights go out. According to Intel, the risk of data loss is no worse than having write caching enabled on a traditional hard drive. In this case, however, the SSD cache would be much larger. To guard against data loss, Smart Response works constantly to push cached writes to the hard drive and freshen the data it has stored for reads. The hard drive won't be perfectly in sync with the SSD in maximized mode, so migrating that kind of setup to a new system requires moving the SSD and hard drive together or disabling the cache beforehand. The cache can be disabled or switched between modes at any time.
Although not applicable to the Z68, it's interesting to note that mobile implementations of Smart Response available in HM67 and QM67 chipsets will change their caching policies to conserve power when a notebook is running on battery. If you're in maximized mode, Smart Response will also attempt to spin down the hard drive more often.
As a purveyor of solid-state drives, Intel couldn't unveil Smart Response without a new SSD sidekick designed specifically for the caching scheme. Behold the Intel 311 Series in all its nakedness:
Otherwise known as Larson Creek, this $110 SSD offers 20GB of 34-nm SLC NAND tied to the same storage controller that has anchored the X25-M line for years. SLC flash memory tends to be reserved for enterprise-class SSDs, but Intel is using it here because it offers the best combination of durability and performance for the task. Despite having just five memory chips onboard, the drive is rated for 200MB/s sequential reads and 105MB/s sequential writes. Random 4KB reads top out at 37,000 IOps, while random writes are pegged at 3,300 IOps.
Curious, I asked Intel about how the 311 Series might fare in a Smart Response config opposite Intel's old X25-V 40GB, which costs around $100. Even with SLC NAND's superior write-erase endurance, the firm expects the X25-V and 311 Series to offer comparable durability under a typical client workloads. However, Intel says the 311 Series will deliver better caching performance.
Time constraints prevented us from testing multiple SSDs with Smart Response, but we did try it out with the 311 Series. The drive was secure-erased before each test to ensure repeatability. We set up Smart Response in enhanced and maximized modes accelerating a Western Digital Caviar Black 1TB hard drive, which also ran the gauntlet without the aid of caching.
The Caviar Black has a built-in DRAM cache, and it's much quicker than the Smart Response configurations in HD Tune's burst speed tests. With the Caviar hitting higher transfer rates than the 311 Series' maximum performance specifications, Smart Response never had a chance in this test. I'm a little surprised to see the maximized mode score slower than the enhanced mode with burst writes, though.
HD Tune's sequential throughput test seems like the sort of thing that Smart Response's built-in intelligence would want to ignore. Caching helps with reads but not with writes.
SSDs are all about lightning-fast access times, and Smart Response puts their potential to good use. Random 4KB reads are wicked-fast regardless of the Smart Response mode, but only the maximized config enjoys an advantage over the Caviar with random writes.
PCMark Vantage's overall HDD score makes things pretty clear, but we've busted out the app's individual test results to shed some additional light on the picture. The HDD score is based on performance with a number of real-world tasks, and Smart Response looks good pretty much across the board.
Only in the Windows Media Center test does the Caviar best the Smart Response configs. Based on the actual transfer rates in that test, it looks like the Caviar's cache played a big role in the drive's victory. Otherwise, Smart Response dominates. The maximized mode is faster in most of the tests, but it's rarely ahead by a big margin.
These final tests were timed with a stopwatch, which didn't detect much advantage for Smart Response when booting up the system. However, the SSD cache loaded our Modern Warfare 2 level in less than half the time it took the Caviar Black on its own.
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