Hybrid Drives and Dual-Drive Systems

Back in the mid 2000s, some of the hard drive manufacturers like Samsung and Seagate theorized that if you add a few GB of flash chips to a spinning HDD, you'd get a so-called "hybrid" drive that approaches the performance of an SSD, with only a slight price difference with a HDD. All of it will fit in the same space as a "regular" HDD, plus you'd get the HDD's overall storage capacity. The flash memory acts as a buffer for oft-used files (like apps or boot files), so your system has the potential for booting faster and launching apps faster. The flash memory isn't directly accessible by the end user, so they can't, for example, install Windows or Linux on the flash chips. In practice, drives like the Seagate Momentus XT work, but they are still more expensive and more complex than simple hard drives. They work best for people like road warriors who need large storage, but need fast boot times, too. Since they're an in-between product, they don't necessarily replace dedicated HDDs nor SSDs.

In a dual-drive system, the system manufacturer will install a small SSD primary drive (C:) for the operating system and apps, while adding a large storage drive (D: or E:) for your files. While in theory this works well, in practice, manufacturers can go too small on the SSD. Windows itself takes up a lot of space on the primary hard drive, and some apps can't be installed on the D: or E: drive. Some capacities like 20GB or 32GB may be too small. For example, the Polywell Poly i2303 i5-2467M comes with a 20GB SSD as the boot drive, and we were unable to complete testing, let alone install usable apps, since there was no room left over once Windows 7 was installed on the C: drive. In our opinion, 80GB is a practical size for the C: drive, with 120GB being even better. Space concerns are like any multi-drive system: You need physical space inside the PC chassis to hold two (or more) drives.

Last but not least, an SSD and an HDD can be combined (like Voltron) on systems with technologies like Intel's Smart Response Technology. SRT uses the SSD invisibly to help the system boot faster and launch apps faster. Like a hybrid drive, the SSD is not directly accessible by the end user; rather, it acts as a cache for files the system needs often (you'll only see one drive, not two). Smart Response Technology requires true SSDs, like those in 2.5-inch form factors, but those drives can be as small as 8GB to 20GB and still provide performance boosts. Since the operating system isn't being installed to the SSD directly, you avoid the drive space problems of the dual-drive configuration mentioned above. On the other hand, your PC will require space for two drives, a requirement that may exclude some small form factor desktops and laptops. You'll also need the SSD and your system's motherboard to support Intel SRT for this scenario to work. All in all it's an interesting workaround.

It's unclear whether SSDs will totally replace traditional spinning hard drives, especially with shared cloud storage waiting in the wings. The price of SSDs is coming down, but still not enough to totally replace the TB of data that some users have in their PCs and Macs. Cloud storage isn't free either: you'll continue to pay as long as you want personal storage on the Internet. Home NAS drives and cloud storage on the Internet will alleviate some storage concerns, but local storage won't go away until we have ubiquitous wireless Internet everywhere, including planes and out in the wilderness. Of course, by that time, there may be something better. I can't wait.