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SSDs vs. hard drives vs. hybrids: Which storage tech is right for you?

Marco Chiappetta | Jan. 18, 2013
With the fairly recent rise of solid-state drives and hybrid drives (which mix standard hard drives with solid-state memory), the storage landscape has significantly altered, creating a cornucopia of confusing options for the everyday consumer.

Solid-state drives

On many levels, solid-state drives are similar to hard drives. They usually connect to a system by way of the SATA interface (though PCI Express-based drives are also available for ultrahigh-performance applications), and they store files just as any other drive does. SSDs, however, eschew the magnetic platters and read/write heads of hard-disk drives in favor of nonvolatile NAND flash memory, so no mechanical parts or magnetic bits are involved.

By ditching the relative slothfulness of moving parts, solid-state drives deliver much better performance. They're the fastest storage option available. And not only can SSDs read and write data much faster than hard drives with most workloads, but they can also access the data much more quickly as well.

Whereas the fastest hard drives can read and write data at about 200MB per second and access data in a few milliseconds, the fastest solid-state drives can achieve 550-MBps (or higher) transfers that essentially saturate the SATA interface, and their typical access times are a fraction of a single millisecond. In a nutshell, SSDs make for a much snappier, much more responsive system, with lightning-fast boot times, application launch times, and file-transfer speeds.

Another huge SSD advantage is durability. Because they have no moving parts, solid-state drives aren't susceptible to damage or degraded performance from vibrations or movement. Drop a system or laptop containing a traditional hard-disk drive, and you have a very real chance of corrupting your data. But a solid-state drive won't--can't--skip a beat.

Solid-state drives aren't without disadvantages, though. For one, SSDs are much more expensive than hard drives in terms of cost per gigabyte. Good, consumer-class solid-state drives run about $0.70 to $1.00 per gigabyte, whereas hard drives cost only a few cents per gigabyte. Solid-state drives don't offer anything near the capacity of hard drives, either: The most popular SSDs have capacities of about 120GB to 256GB, with 512GB to 1TB models reserved only for those with gargantuan budgets.

SSD performance also varies depending on how full the drive is, or if it has been purged of data. Idle garbage collection or a feature called TRIM can help restore the performance of a "dirty" SSD, but that requires driver and OS support. (Windows 7 and 8 support TRIM.) Because the capacity is relatively small and performance is affected by how full the drive may be, many SSD users find themselves regularly moving less-performance-intensive data (such as documents or media collections) off their solid-state drives and onto traditional hard drives.

Another concern: When SSDs fail, they tend to do so without warning. Hard drives, however, will usually start to show signs of failure by throwing a S.M.A.R.T. error or suffering from a few bad blocks. In our experience, SSDs simply die without waving many--if any--red flags.


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