Conventional hard-disk drives still dominate the storage market and will certainly continue to do so for the foreseeable future for applications requiring as much capacity as people's and organisations' budgets can buy.
However, the market has become somewhat complicated with various new types of more specialised hard-disk drives. V3 therefore caught up with Toshiba's Rainer W. Kaese to find out more.
V3: How do NAS and surveillance HDDs differ from regular desktop drives?
Network-attached storage (NAS) and surveillance hard disk drives are designed and tested to deliver reliable, long-term 24x7 operation. The drives found in most desktop and laptop computers aren't built with this kind of continuous usage in mind and, while they'll do a job, reliability in the long term can't be assured.
Moreover, NAS hard-disk drives, such as the Toshiba N300 and surveillance hard disk drives, typically incorporate rotational vibration sensors. These enable multiple drives to be safely mounted close together in the same enclosure, and still operate reliably. Without the sensors, there's a risk of rotational vibration affecting other drives in a multi-bay system.
V3: Where do NAS and surveillance drives sit in relation to the high-end HDDs found in servers?
Like NAS and surveillance hard-disk drives, server-grade hard drives are designed for 24x7 operation and for systems where multiple disks operate in close proximity. The key difference is around data workloads: server hard disks are built for the high-volume work associated with large numbers of users and intensively used production databases. NAS and surveillance hard disks are engineered for the less-demanding workloads typical of surveillance or central network data storage.
Consequently, NAS and surveillance hard-disk drives sit between server-grade and desktop-type drives, both in terms of workload capability and price.
V3: With more and more data being stored in the cloud, what is driving the continued demand for local storage, particularly network-attached storage?
We've all heard about the global data explosion, and while the cloud offers part of the storage solution, there are situations where data needs to be housed locally. There is also an increasing appreciation of the importance of robust, reliable backups. Combined with the world's ever-growing data volumes, this need to keep copies of data is multiplying storage capacity requirements across the board, from home users with NAS and surveillance systems to large enterprises.
NAS systems have evolved and now incorporate many of the features you would previously only see in more-expensive enterprise storage server systems with Fibre Channel connections. This means that as storage demands grow, particularly in businesses, NAS systems with (for example) Toshiba's N300 NAS hard-disk drive can be used for ever-larger parts of it.
V3: With SSDs getting cheaper all the time, is there still a place for conventional disk storage?
The cost of solid state drives (SSDs) has come down considerably and, indeed, some high-end NAS systems also use them for caching to improve performance.
SSDs are all about performance, but spinning-disk HDDs still have the upper hand when it comes to providing large amounts of capacity economically.
With lots of research and development, particularly to increase the data density and number of platter is going on around HDDs, we should see the cost per gigabyte continue to fall and significant increases in capacity. As a result, they'll remain an essential part of the storage ecosystem for at least the next 10 years.
V3: Why is it that hard-disk drives can scale more economically than SSDs?
In essence, an SSD is made up of storage cells, each with its own read/write transistor and wiring. Despite smaller geometries and 3D cell stacking technology, to double the capacity, you need to double the number of storage cells, which in turn doubles the number of transistors and wires required - and scales up the cost.
With a conventional hard-disk drive, there are ways to increase the recording density and add less expensive platters without increasing the drive's physical size or significantly adding to its cost.
V3: What capacities can we expect to see from NAS-grade disk drives in the short- and medium-term?
We've recently seen improvements to the way data is recorded and to the number of platters you can fit into the standard 3.5-inch form factor. Both these enhancements mean you can now get NAS-grade drives with capacities up to 8 TB.
The next steps could be to bring the helium-filled disks - which you can already find in some server-grade applications - to NAS systems. This enables the platters to be thinner, meaning you can fit more of them into the same size of enclosure. This development should see NAS drive capacities boosted to around 14 TB.
There's also work going on in the HDD industry to develop new recording technologies, which should see NAS HDD capacities edge towards and eventually break through the 40 TB capacity barrier.
Rainer W. Kaese is senior manager, Business Development Storage Products, at Toshiba Electronics Europe, where he's worked for more than 20 years.
He initially specialised in application specific integrated circuits and has managed Toshiba's ASIC Design Centre. He is currently responsible for the introduction of Toshiba's Enterprise hard-disk and SSD products into datacentres, cloud computing and enterprise applications.
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