Solid-state drives: 10 questions, 10 solid answers

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7. What's the difference between AHCI and IDE?

Modern SATA controllers run in two modes: AHCI (Advanced Host Control Interface) or the standard IDE (Integrated Drive Electronics). AHCI offers advanced techniques that are especially useful for SSDs such as NCQ (Native Command Queuing), which has an effect on performance, and a couple of power management enhancements. While the performance benefits of AHCI may be negligible, the benefits in power consumption could be quite significant -- especially on laptops.

On the other side, SSD controllers have unique properties that may only work in AHCI (such as the TRIM command). IDE, however, may offer better performance with other controllers. Benchmarkreviews actually compared the speed of several SSDs running AHCI versus IDE mode -- if your SSD isn't listed, try performing the same benchmarks with IDE and AHCI enabled.

To check whether you're running in IDE or AHCI mode, go to "Device Manager" and expand the "IDE ATA/ATAPI-Controller" section. If you don't see AHCI mentioned, you're running in IDE mode:

To enable AHCI, fire up your BIOS and try to find the setting for "SATA Mode" (or similar) and enable AHCI. If Windows doesn't automatically enable AHCI for you, follow this guide to activate the AHCI driver.

8. When will SSDs finally hit the same price per GB point as traditional HDDs?

SSDs are already nearing the $.50/GB point (you'll find some 128GB SSDs around the $70 mark on NewEgg), but it's nowhere near the average of traditional HDDs. It took 2-3 years for SSDs to go below $1/GB. To give you a comparison: The price per GB of a traditional HDD is currently at $.05/GB. I estimate it will take another 3-5 years until we finally see SSD prices on par with HDD prices.

9. Are hybrid disks worth the money?

In the Windows Vista era, many HDD makers combined smaller (4GB-16GB) flash cells into their mechanical HDDs. The goal was to use faster flash storage as a cache for frequently used data. The firmware and Windows "learn" what data the user needs frequently and copies it over into this cache. A couple of manufacturers (e.g., Seagate with their Momentus XT) still offer hybrid drives and they're a less pricey alternative to SSDs. You'll get a hybrid drive for around $120 with up to 750GB of HDD storage and 4GB SSD. If your usage behavior rarely changes, you may be perfectly happy with these drives. If all you do is run the same applications (browser, mail, office, coding, etc.) over and over, you'll enjoy performance on par with today's SSDs. However, if you change your usage behavior more often and need quick performance for ALL your data (and not just programs or Windows), you'll be much better off with an SSD.

10. SSDs in the enterprise. Worth the investment?

SSDs hold promise for data centers and enterprises. However, due to their premium price you'll have to specify applications where SSDs can be deployed. You need to identify areas and applications of your enterprise, where performance sensitive data (realtime research and VMs, for example) matters and equip the servers/clients with SSDs but stay with the traditional technology in areas where speed really isn't a priority (backup, storage, etc.). When you're not throwing SSDs blindly into your infrastructure, you'll likely see a return on investment due to increased performance and lower power consumption.

I'd also advise you to chose SSDS with high IOPS (Input/Output Operations Per Second) and a high MTBF value (Mean Time Between Failures), such as Kingston's SSDNow enterprise series or the Hitachi Ultrastar SSD400M.

Now read: Hard disk drives vs. solid-state drives: Are SSDs finally worth the money?

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