A solid-state drive (SSD), like the name suggests, consists of flash memory, similar to what's in USB flash drives...
or Secure Digital media cards.
From the outside, SSDs intended for notebook computers have the size, shape and SATA interface of their 1.8-inch and 2.5-inch hard disk drive (HDD) counterparts, and appear the same to the operating system.
However, there are some important differences:
- Capacity and price
Notebook HDDs today go up to 500 GB (although 160 GB to 320 GB is more typical), and cost about $1/GB through a notebook vendor, or .50/GB or .25/GB as swap-in component purchases from sources like Micro Center or Newegg.com.
Typical notebook-sized SSD capacities are 32 GB, 64 GB, 80 GB, 128 GB and 160 GB. The first 256 GB notebook SSDs are expected by the end of 2008, and can add several hundred to more than a thousand dollars to the cost of a notebook -- or cost $3/GB to $10 per gigabyte purchased separately.
And unless a user has lots of data, or feels the need to consume mass quantities of music and videos, 32 GB is more than enough space. (A full Windows OS and Office install plus other typical applications can be squeezed into 3 GB or 4 GB, and fits quite comfortably in under 10 GB.)
- Reliability and availability
SSDs will survive, and keep working, through bumps and thumps that can either damage HDDs, or cause the heads to auto-park, which can interfere with operations that need disk access.
Depending on your application and configuration, SSDs may speed up anything from boot time to application loading to application performance. Some users report seeing a meaningful difference, but many others don't.
- Environmental factors
Many hard drives don't do well at high altitudes, due to the lower air pressure. However, SSDs should still work under these conditions. Even when hard drives work in higher altitudes, they may degrade or fail sooner. SSDs like Super Talent's I-temp SSDs are designed to tolerate extreme temperature, vibration or humidity conditions.
There are many differences in SSD, and they are not all created equal.
There are two different architectural approaches -- Single-level Cell (SLC) and Multi-level Cell (MLC).Single-level Cell SDDs are more expensive and historically more reliable. However, MLC SDDs from vendors like Intel are closing the performance and reliability gap versus SLC SDDs.
Also, there may be differences due to each vendor's drivers, software, algorithms and manufacturing technology. For example, Intel uses 10 parallel NAND flash channels with its MLC SSDs. This supports up to 32 concurrent operations through its Native Command Queuing, and Intel says it has an extremely low Write Amplification Factor compared to other vendors. This factor represents the amount of overhead in doing a write, which impacts how fast the chip will wear down and improves the performance and longevity of its MLC and SLC NAND flash.
Notebook vendors offering SSD-based notebooks, or SSD options, include Apple, Dell, Hewlett-Packard Co., Lenovo, Samsung and Toshiba. Intel, Samsung and other vendors offer SSD notebook hard drives, and you can find and buy SSDs from NewEgg.com and other outlets.
Many of the $299 to sub-$1,000, two to three pound "netbook" computers, like the Asus Eee, also use solid-state storage, which is for smaller capacities and is less expensive than hard drives. Many netbooks also offer a choice of SDD or HDD.
For now, says Joseph Unsworth, research director, NAND flash semiconductors, Gartner Inc., "Companies should consider SSD if their needs demand greater reliability and higher performance with relatively low storage requirements."
For example, field service, industrial, military and mobile/in-vehicle applications, where there's lots of environmental stress, and/or timely fix or return isn't an option, SSDs (and a semi-rugged or fully-rugged notebook, overall), are likely to be a good investment. Equally, SSDs may be worth the added price bump for circumstances where other benefits like low-noise or performance/runtime improvements are meaningful, e.g., for lawyers and frequent travelers.
Otherwise, says Unsworth, "Gartner has recommended that outside of [these] special circumstances, companies should hold off on mainstream PC SSD adoption until 2010. This will allow more competition, considerably lower prices (128 GB available at around a $200 price-point) and technological advancements that will enhance the value proposition."
Meanwhile, while a full SSD is expensive, if your notebook can accommodate it, you can get the outstanding performance benefit of an SSD with a comparatively inexpensive Intel Turbo Memory ExpressCard or mini-PCIe add-on/in, notes Howard Locker, director of new technology, Lenovo. "In addition to the hard drive, my ThinkPad has 4 GB of solid-state memory that caches everything, and the performance is unbelievable."
Daniel P. Dern is an independent technology writer. He can be reached at firstname.lastname@example.org. His web site is www.dern.com and his technology blog is Let us know. Please let others know how useful this tip was via the rating scale below.
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