Hard disk drives rule for high capacity

Some are predicting that solid state drives will take over the storage world, wiping out hard disk drives. When you take a closer look, however, it becomes apparent those predictions are premature.

Some are predicting that solid state drives will take over the storage world, wiping out hard disk drives. When you take a closer look, however, it becomes apparent those predictions are premature.

With the explosion of content, digital media and government regulations for maintaining copies of electronic records, including e-mail, the need for storage is growing by leaps and bounds. And as capacity needs increase, so does the importance of HDDs. Only HDD technology provides the right balance between low cost per bit and high performance for online access, both now and into the future.

The way the technologies measure up in key areas shows they can continue to coexist.

* Technology growth. HDDs are a great bargain, and getting better all the time. HDD capacity is doubling in less than every two years. SSD technology, starting from far behind on a cost-per-bit basis, has been advancing slightly faster for the past few years, but will run into difficulty in the next two to three years when trying to scale to smaller dimensions. This will slow the pace of development to something comparable to HDD. It is very likely that SSD will never reach the very low cost per bit of storage of a high-capacity disk drive.

* Notebooks. SSD drives might be a good option for notebook users because of weight and reliability issues, but potential adoption could be disrupted by consumer desire for ever greater capacity to support evolving needs. With the explosion of audio, video and digital photos that people want to store, organize and quickly access on their notebooks, hundreds of gigabytes of storage are required. That can only be satisfied in an affordable way using HDDs, which will be true for a long time.

Some might suggest users don’t need to store that much data on the notebook, that it can reside on a server in the cloud.

Network-accessible storage is here and essential in the business world and on a personal level can be used for sharing family photos, enjoying digital content or for social networking. But even storage in the cloud doesn’t eliminate the need for high-capacity local storage because high-speed access to the Internet does not exist universally (for example, on an airplane).

Even if notebooks do go to SSD, with the volume of digital media that people have, users may need an external hard drive to easily access that data.

* Desktops. Desktops are different — many desktops in the corporate environment sit in a fixed location and are used for a limited set of applications, such as to access a rental car application. Control of corporate information is easier when it is centrally located. For those cases, SSD will start to make more sense as the price for low-capacity SSDs falls below $100.

Other desktops used as engineering workstations or high-performance gaming machines tend to need very fast access to large amounts of data. In those cases, SSDs are not affordable, and network access to everything is not practical or fast enough. Hard drives on these machines will remain the best choice.

* Performance. SSD drives are good at random read operations. This is the basis for claims that boot times and program loads for some applications are faster. However, the write process for SSD drives is complicated. Large blocks must be erased before data can be written. Because SSD wears out with many writes, the controller in an SSD must move data around so all of the memory locations see similar numbers of writes. The result is that some of today’s less-expensive — but still very expensive compared with hard drives — SSDs with poor random write performance are being used in notebooks.

If you copy hundreds of files from one location on the disk to another — such as copying the photos taken of your vacation to another directory to edit them without touching the originals — it can take 10 times longer using SSD drives than it would using a hard drive. As SSD engineers gain more experience and knowledge, the random write performance should become very good. However, this shows that SSD performance is not always as great as advertised and can be worse than HDDs. As SSD performance improves, some of the potential performance and low-power benefits will be realized by its use in combination with HDDs.

* Cost. HDDs are still less expensive than flash drives, especially in larger capacities. A 1TB HDD retails for less than $400; a 1TB SSD would cost more than $10,000. In another five years, we will see 5TB to 10TB HDDs for less than $300. That’s about 5 cents per gigabyte. When will SSDs get there? That’s more than a factor of 100 from where SSD is now, so SSD may never be cost-efficient enough for large amounts of storage.

SSDs have taken over certain segments previously owned by HDDs, such as smaller MP3 players. But exploding storage capacities will continue to drive demand for low-cost HDDs, ensuring the technologies will coexist for years to come.

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