|Feature Story 1|
By WILLIAM VAN WINKLE
With all the hype and buzz around solid state drives (SSDs) over the last few months, you’d think that hard disk technology, that old relic of magnetic particles and LP-like spinning platters, was already dead and buried. But the reality is that hard drives still own the vast majority of today’s storage market. Market analysis firm Web-Feet places the SSD industry at $7.5 billion in 2012. In a declining market, Seagate did $3 billion in just the third quarter of this year alone. Hard disks aren’t going anywhere anytime soon. The question is: What storage opportunities could you be missing right now because you’ve turned a blind eye to what’s new in hard disk technologies?
Hard drives aren’t sitting around waiting to die. Manufacturers continue to innovate with disk technology, and more value continues to pour into the format, making it ever more attractive to buyers. If you’ve felt like hard disk storage is flat and boring, just a matter of dollars and megabytes, then it’s time to take a fresh look. Hard drives have an increasingly strong story to offset the SSD buzz that’s about a lot more than pricing. If you’re not aware of this whole story, then you’re missing out on a lot of sales opportunities.
There are three top reasons to buy a solid state drive: ruggedness, power savings, and performance. Anyone who’s even brushed up against an SSD knows this, but the case for hard drives in SSD’s back yard may be stronger than you suspect. Know the details and you could have a lucrative competitive advantage.
Now consider that today’s SSDs boast a shock rating of 1,500 G, a number that’s roughly equivalent to dropping a drive from a 27-foot height. When we asked one SSD manufacturer if its drive could really withstand this—not just the flash modules but the entire drive, including housing and plastic connectors—we were met with waffling. Moreover, the key failure point in notebooks due to shock is not the drive but the screen.
This wasn’t always the case. In the days before hard drives had accelerometers and parking ramps, it didn’t take much of a bump to cause a “head slap” or “head crash,” when the drive’s read/write head would be jarred into making contact with the underlying platter. If the platter was spinning, this would gouge a rut into the surface and damage the data in those tracks if not outright destroy the drive. But in recent years, manufacturers have built in accelerometers, similar to those used to deploy automotive airbags. In a state of free fall, as when a system is knocked off a desk, the g-force drops to near zero. When the accelerometer detects this, it commands the head to retract up the drive ramp into a location away from the media.
If you swing a bat at a hard drive in operation on your test bench, the drive is probably toast. In operation, a drive like the Seagate Momentus 7200 FDE specs a 350 G shock tolerance at 2 ms, meaning the length of time between shock pulses, and 1,000 G at 1 ms. This latter number is generally considered the non-operational rating, meaning the drive is simply sitting. The platters may be spinning, but the heads are not floating over the media; there are no read/write operations in progress. As a point of comparison, the Seagate Barracuda V desktop drive from 2002 featured a 2 ms operating spec of only 63 G and a non-operating spec of 350 G. Clearly, hard drives have come a long way in just a few years.
One of the most telling charts from this follow-up article has to do with streaming read I/Os per watt, the ubiquitous performance-per-watt rating that’s quickly becoming the new criterion of choice. Of the four hard drives tested, Samsung’s 320GB HM320JI scored 248. Solid state drives from Crucial, Mtron, and SanDisk fell into the 281 to 317 range—hardly a ringing triumph considering that reads are SSD’s strength. The lone star in this test is OCZ’s SATA/300 SSD, which pulled in a phenomenal score of 1391. This is what the authors mean by “yet.” SSD, when done right, has the potential to excel in these operations, but thus far the results have been generally mediocre.
One other point from this article is worth noting: average power draw during DVD video (on-drive VOB file) playback. The five SSDs tested by Tom’s averaged a draw of 1.24 watts. The four hard drives tested averaged 1.35W, and Hitachi’s 160GB Travelstar 7K200 scored a slim 0.8W, handily beating the SSD average. Similar results appear in lowest idle drive power draw, with the Travelstar 7K200 pulling down 0.7W at idle compared to the SSD average of 1.08 watts.
To learn why Hitachi fares so well in these power comparisons, we talked with Larry Swezey, Hitachi GST’s director of marketing for consumer and commercial hard disk drives. It turns out that Hitachi is now in its seventh generation of energy-saving drive designs. Starting with last year’s P7K500 and continuing with the current 7K1000.B 3.5" desktop drives, the company migrated the system-on-chip (SOC) used in its energy-sipping, 2.5" Travelstar drives over to the Deskstar line. Among other things, the SOC uses a more power-efficient drive interface and switching regulators instead of older linear voltage regulators.
The 7K1000.B normally specs 6.2W for random reads and writes, 3.6W at idle, and 0.8W in both sleep and standby. However, the drive features two advanced power management modes. The first is called unload idle, and it involves unloading the heads to the ramp and shutting down the servo for a power draw of only 3.1W. The second, low RPM idle, is like unload idle but it also drops the platter rotation rate to 4500 RPM, yielding a 40% drop under standard idle to just 1.9 watts. The drive monitors usage and can switch into these modes dynamically and independently of any external storage controller. An idle mode savings of up to 1.7W may not sound massive, but when you consider that current ENERGY STAR 4.0 requirements mandate a 50W idle mode maximum for the entire system, the leeway of having an extra 1.7W in your power budget takes on new significance.
“Other people have taken the lower RPM approach,” says Swezey. “That’s valid. It works well in external storage, where you’re limited by the speed of the USB bus. But the whole world is used to a certain level of data transfer, and that’s directly related to how fast the I/O is coming off the drive. We set out on both our 2.5" and 3.5" lines to give people the option to go to higher performance, higher spin speeds, but not make them pay for it with higher power consumption. We did a tremendous amount of work in the electronics channel design, the motor drivers, and so forth to get you there. For example, we now have a 7200 RPM drive with about .1W difference from the industry average 5400 RPM drive.”
Running MobileMark 2002 (Patch 2) over four hours, Hitachi’s own benchmarks show an average power consumption for the Travelstar 7K100 of only 0.96 watts. Stepping down to the 5K100 (5400 RPM vs. 7200 RPM) gets you down to 0.77 watts. Now, true enough, an SSD like Intel’s X25-M specs an active draw of 0.15W and an idle of 0.06W—a serious delta compared to hard drives. Even a new, leading drive like Hitachi’s just-released, 500GB Travelstar 5K500.B can only get read/write power consumption down to 1.4 watts.
There are two take-aways here. On one hand, we can see that, going forward, well-made SSDs will outstrip hard drives on power savings. On the other hand, real-world tests show that exactly how the drives are used and evaluated can have a tremendous impact on actual power draw, and the picture rarely looks as good for the average SSD as it does for the average power-conscious hard drive. Bring price back into the picture.
But power savings on hard drives don’t stop there. Most independent reviews set up a test configuration, run the benchmarks on one drive tethered to the integrated controller, and then simply swap drives into the same system, which is often a notebook because that’s what makes sense in a consumer environment that would compare SSD against HDD. What if we consider the advantages of modern power savings technologies applied to hard drives at the controller level? After all, 2.5" drives are increasingly being used in server solutions, and in environments where capacity and power matter more than raw platter performance, a drive like Hitachi’s E5K500.B (identical to the consumer drive but modified for 24x7, enterprise-class availability) makes excellent sense.
Power, Part 2: Saving the Server
It seems incredible that no other storage controller manufacturer has sought to leverage these lower RPM codes, but thus far Adaptec seems to be the only one doing so. According to the company, an average hard drive consumes 10W to 12W during normal operation at full RPM. In the power-off state when platters are stalled, consumption drops to 3 watts. In this new standby middle ground, drives use 5W to 7W and require only about one-third the time to spin back up to full speed.
Adaptec tested many drives and offers a few real-world examples to prove its power savings. The Hitachi HDS721050KLA330 runs at 10.8W under full load, 8.7W at standby, and 3.3W at idle—not a massive savings, but a 19.5% savings from standby is nothing to sneeze at. You start to sense the true potential of standby in the Hitachi HDT25050VLA360, which goes from 10.0W at full speed to a remarkable 3.2W at standby, just a breath above the drive’s 2.3W idle mode. Clearly, Adaptec’s claim of 70% possible energy savings is no, um, idle boast.
Standby mode obviously offers a lot of performance vs. energy savings compromise, but Adaptec goes further by equipping its storage management software with the ability to dictate when any or all drives will be active.
Adaptec study numbers break down drive idle time by target application, showing that file and print server drives are 75% idle. Disk-to-disk backup systems twiddle their thumbs 80% of the time, and bulk email and media systems (think Yahoo! mail and photo sharing sites) have drives doing nothing 95% of the time. Data goes through high usage when it’s new, but after a couple of months it goes into a very long hibernation. Adaptec’s Intelligent Power Management prevents the unnecessary and frequent pings that wake the drives up by caching unnecessary messages on the storage controller and storing them until the 256MB or 512MB of cache is full. At this point, the card will dump the messages to the drives en masse so they’re only spun up once, then soon powered back down. A “verify” function can optionally spin the drives up periodically to confirm their health. Otherwise Adaptec’s software can keep drives quiet for many hours whereas conventional OS-based power management often sends queries every few minutes.
“The impressiveness of this,” says Suresh Panikar, director of worldwide marketing at Adaptec, “is that Intelligent Power Management allows for the identification of idle time and then makes good use of it by providing control to IT managers or systems integrators to put that policy in place, which then dictates the power consumption overall in a storage system over time. A discussion of momentary time would not be very interesting. On a weekly, monthly, annual basis, there you’ll see real improvement in power consumption and utility costs. And ANY drive available today should be able to show at least some improvement from using Intelligent Power Management.”
The industry normally figures a 1:1 ratio for energy consumption and cooling costs. In other words, for every dollar a drive consumes in electricity, it costs another dollar to cool that drive to recommended levels. Adaptec chose the more conservative ratio of 0.7. At a price of 10 cents per kilowatt-hour, drive power of 8W, and 80% idle time, Adaptec figures that six months of Intelligent Power Management can save $19 for every four drives. At 96 drives, that’s $457 in savings every six months, and so on. Even in the small office space where these numbers won’t equate to big dollars, the green message remains persuasive.
Obviously, with no spinning platters, Intelligent Power Management can offer little benefit for SSDs, although Adaptec is already making vague mentions about having something for that market in 2009. We should also note that Intelligent Power Management reduces another advantage of SSDs: noise. SSDs may be totally silent 24x7, but Adaptec’s technology definitely shaves a lot of cumulative decibels from storage servers. For anyone who has to work near such machines, the drop in total noise should be greatly appreciated.
One of the best comparative assessments we’ve seen to date of a performance-oriented consumer hard drive and solid state drive is Anandtech’s recent look at Intel’s X25-M. If nothing else, this roundup shows two things: The future for SSD looks very bright once prices come down, and there remain many, many situations in which hard disk technology is still the obvious choice.
Consider Anandtech’s PCMark Vantage tests, which seek to reflect real-world performance. The key hard drive to compare against is Western Digital’s VelociRaptor, a SATA-based screamer with 2.5" platters and a 10,000 RPM spin rate that’s generally targeted at gamers or businesses looking for a less expensive alternative to SAS. In the all-inclusive PCMark test, Intel’s drive scored 9044 to WD’s 6676—a 26% advantage for Intel. On the other hand, the 80GB X25-M is expected to carry a $595 price tag, $7.44 per gigabyte, versus $270 (current Newegg) for the 300GB VelociRaptor, yielding 90 cents per gigabyte. Now how persuasive is that PCMark delta?
Anandtech’s multitasking results were also intriguing. While extracting a 5GB archive, the author ran Photoshop after 30 seconds of extraction. The VelociRaptor scored 116 seconds to complete extraction, significantly better than Intel’s 161 seconds. However, launching Photoshop during this test took the X25-M only 12.2 seconds compared to 27.3 for the VelociRaptor. Again, this makes the point that the only way to really determine which technology and specific drive is best for your clients is to test them under the customer’s unique environment.
In general, it’s safe to say that SSD will win in random read tests while hard drives outperform in sequential reads, sequential writes, and random writes. For instance, Anandtech’s prior look at SSDs pitted the VelociRaptor against the latest 64GB SSDs from OCZ and Samsung (essentially the same drive). Performing Nero Recode 2 on a ripped movie, the VelociRaptor scored 124 to the OCZ and Samsung’s 128. Factor pricing back in, and the choice is obvious. In fact, consider implementing a two-drive RAID 0 with hard disks to further boost performance; you’ll still be far ahead compared to SDD in price-per-gig.
Need Another HDD Advantage?
Back in 2007, Hitachi implemented what we call bulk data encryption on our drives. We build a 128-bit AES engine into the main drive SOC. So if a customer wanted us to ship them a drive with encryption enabled, we could do that. That ended up in a couple of major OEM notebooks. The beauty of it was that it’s a very high-level encryption engine that’s on full-time. It’s not using any of the software in the system or taking CPU time, but the big detriment of software-based encryption is you take about a 15% performance hit. That went away. As long as you had a BIOS that supported the traditional HDD password, you could set it, and the drive encrypted everything that came across the interface and decrypted everything that came back. In the unfortunate event that the system was stolen, there was absolutely no easy way—“easy” being anything short of using supercomputers for months to try to crack the encryption—to get at that data.
“Say you talk to a Morgan Stanley, and you say, ‘I’ve got this great drive encryption for you. It’s very safe, uses an AES engine, blah blah blah,’” says Hitachi GST’s Larry Swezey. “The guy says, ‘OK, but how can I prove that this is enabled?’ His problem is that if they lose a laptop and can’t absolutely show an audit trace to prove that the laptop did indeed have the encryption enabled, they can’t know with assurance that the data was protected when it was lost. Then we get letters telling us that at some point our valuable data was lost, we’ll pay for credit for a year, good luck.”
To the best of our knowledge, no SSD to date has incorporated full-disk AES encryption, which seems very odd given the high-end nature of the product today. This is just one more instance of a hard drive advantage that is often overlooked amidst all of the SSD brouhaha. We’re not saying that SSD won’t be king someday. But this is today, and in the wide majority of applications and user needs, hard disks still reign. The trick is to find the smart ways to prove HDD’s superiority, even over other hard disk competitors, and turn such advantages into profit for you.
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