MacBook Air face-off: HDD vs SSD (with video)
The MacBook Air's fixed battery and 3-5 hours of runtime make any opportunity to save power a critical feature. Users can't expect the SSD option to make a huge impact on how long they can use the Air on a charge though. The biggest power savings impact isn't directly observed in battery use, but rather shows up again in terms of performance.
Savvy laptop users know several tricks to get the most life span from their machine: drop the display brightness, turn off unnecessary radios, allow the unit to sleep, and let the hard drive spin down when not in use. The advantage of an SSD is that it doesn't need to spin down. A conventional HDD is kept spinning at all times in order to be responsive. When the Energy Saver System Preference is set to "put hard drives to sleep when possible," the system will spin it down, reducing the power drain but making things awkwardly pause every time the disk is accessed due to the time needed to spin the drive up to speed.
The SSD is not only never spinning, it's also never needing to spin up, meaning no irritating pause when files are opened or applications are launched. This also makes a significant impact on boot times, as the HDD has to initially spin up from a cold stop while the SSD is ready to rock from the moment power hits it. It also means the SSD has all the performance of a spinning HDD without needing to scrape at performance with disk sleep.
In order to accurately test the Air's battery life, it needs to be cycled multiple times to achieve its full capacity. We pulled a full MPEG-2 DVD image over WiFi more than once over a three hour period before we could exhaust the thin strip of Lithium Polymer that powers the Air. In more conventional use involving web browsing and writing, using WiFi with power management settings on Better Energy Savings and the screen dimmed to half brightness, we managed to pull a full five hours and ten minutes of use from the HDD Air, and fifteen minutes less time from SSD Air doing similar but not identical work.
The SSD we tested also had a faster processor, which may have ate into its battery life slightly faster, but it was also a week newer, so it didn't have time to cycle through as many battery recharges. Charging the battery took longer than depleting it, as long as 8 hours with the included power adapter or 5 hours using a MacBook Pro adapter. Other reviewers were unable to get the full rating from the Air's battery because in many cases, they purposely defeated the battery saving technology used to coax time from the battery and ran looping MP3 playback rather than actually using the laptop as a laptop.
The MacBook Air certainly makes a poor $1799 iPod and shouldn't be recommended for that purpose. Our mix of using Safari, iChat, TextEdit, and Dictionary to do actual work regularly accessed the wireless networking and disk, as TextEdit auto-saved the documents we worked on and spun up the drive at regular intervals in order to do this. Bluetooth was turned off.
SSD is also able to withstand extreme shock, high altitude, vibration, and temperature extremes better than a conventional hard drive. This impacts overall reliability, expected life span, and the general fragility of the system. One of the first components of a laptop to die is its hard drive, due to the complex moving parts, intense heat, and mechanical wear that it has to withstand. An SSD has none of these reasons to wear out or fail, making it as reliable as the logic board or any other solid state components. Another side effect of being solid state is that the SSD is also completely silent.
How much more reliable is the SSD over a conventional HDD? That would be pretty impossibly difficult to benchmark accurately. In defense of the Air's HDD, reader Rick Hyman noted that our review of the MacBook Air "seems to infer the 1.8 inch HD used in the MBA has the same failure modes as the 1.8 in HDs used in iPods. This is not true. The MBA appears to use a new 1.8 in HD announced by Toshiba in December. This new HD is more rugged and can handle more robust use than the older HDs. Certainly, this new 1.8 in HD was a necessity for Apple, since no laptop could be reasonable expected to use the type of HDs used in iPods. The slower speeds of the 1.8 in HD remain as an issue."
The first batch of Airs are using Samsung HS0822HB 1.8" HDD components. On its website, Samsung lists the target applications of this model as "camcorders, MP3 players, navigators, personal media players, UMPC," but not laptops. That's likely because no PC maker has built a full size 13.3" laptop that is ultra thin like the Air, and therefore most laptops use 2.5" mechanisms instead. The Air's SSD is listed as MCCOE64GEMPP, and is also made by Samsung. That company has long been the supplier of lots of Apple's Flash RAM, SDRAM, and hard drives, although not an exclusive source for any of those components. New batches of Airs will likely use other parts.
Worth the Grand?
While new 1.8" HDD used in the Air would certainly seem to need to be in a higher duty class than those used in the iPods, it's still a tiny mechanism and hasn't been proven in long term use. This newness may push more users to consider the expensive but faster and more reliable SSD option despite its much higher cost and limited storage capacity. SSD is new too, but there's nothing unknown about how memory chips wear out.
For users to whom cost is not a big deal, the SSD option paired with the processor upgrade delivers the fastest possible experience, with significantly faster booting, application launching, and shutdown, and with no spin up lag even when working from the battery in power saving mode. Everyone else will need to weigh their needs for delicious luxury with more practical considerations such as storage capacity and budget.
Users buying the Air because it looks great probably won't see any reason to spring for the more expensive version, but business users attracted to its full sized mobility will find a lot to like about the SSD, which makes it both that much more-full sized in terms of speed and more mobile in terms of spin-free reliability.
AppleInsider's MacBook Air review series
For more on AppleInsider's ongoing in-depth look at the MacBook Air, check out these earlier installments:
MacBook Air (HDD model): an in-depth review
Early adopter issues: MacBook Air and Migration Assistant
Early adopter issues: MacBook Air, SuperDrive, Remote Disc and Install
MacBook Air spawns new software solutions for missing hardware
How the MacBook Air stacks up against other ultra-light notebooks
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