Time was, tape media was commonly used for backing up data, with bulky spools of magnetic tape being stored in vast tape libraries in the data centre as well as in remote locations off-site.
This media has long been viewed as the most appropriate for bulk data storage, backup, archiving and data interchange. One of the reasons is that tape - for many years - had a more favourable capacity/price ratio compared to other options, such as hard disks.
However, as the price of hard disk capacity began falling in around 2004, so other storage formats began to appear on the market. Some were proprietary or specific to certain products, others more generic in nature. Most significantly, the size of the medium began to shrink, with the devices arriving in smaller and smaller packages.
Although tape had progressed from large format to cartridge types, one of the biggest drawbacks of the medium is its sequential access. To find a section of lost data during the recovery process, the tape has to be physically traversed, often slowing access times to a crawl.
This was one of the first hurdles to be overcome by hard disk backup devices. Apart from a much more manageable size and therefore ease of use, hard disk storage devices could be connected via local interfaces such as SCSI, USB or eSATA to speed data throughput, or via longer distance technologies such as Ethernet, iSCSI or Fibre Channel, to allow for the remote location of the backup repository.
Some hard disk-based backup systems virtually replicated tape libraries, allowing support for data deduplication technologies designed to reduce the amount of disk storage capacity required by an order of magnitude or more.
Innovation abounds
In many applications today, hard disk storage is giving way to even more compact media, such as recordable CDs. A key advantage of CDs is that they can be restored on any machine with a CD-ROM drive - including PCs. Another is price; recordable CDs are inexpensive and readily available.
Another format finding increasing favour in the data centre is recordable DVD, mainly because of its WORM (write once, read many) format which positions it as useful for archival purposes since the data, once copied, cannot be altered.
The advent of solid state storage and solid state drives has reduced the physical size of storage devices even further.
John Hope-Bailie is technical director of Demand Data.
The newer HD-DVDs and Blu-ray disks allow greater amounts of data to be stored on a single disk, further reducing the physical size of the backup repository required.
The advent of solid state storage and solid state drives (SSDs) has reduced the physical size of storage devices even further. SSD technology is familiar as it is used in flash memory chips - the tiny circuits inside MP3 music players, smartphones and USB flash drives.
Driving the adoption of SSDs at enterprise level is the fact that server processors double their compute capacity every 18 to 24 months - according to Moore's Law.
An SSD is able to emulate a hard disk drive interface, thus easily replacing it in most applications. With no moving parts, solid-state drives are often more reliable than hard disks and - with green issues in mind - consume less electricity as no cooling is needed.
Moving forward
The most significant advantages of solid state technology are ultra-fast access times (usually around 10 microseconds) and low latency due to the absence of mechanical delays. As a result, they are increasing deployed in enterprise servers and data storage repositories as a way to speed up mission-critical applications.
These advantages help to offset their cost, which currently is more than double that of the equivalent capacity hard disk drives. That said, the costs of SSD materials are said to be falling by 50% on an annualised basis. At the same time, the number of SSD manufacturers is growing as the adoption rate of SSDs in the enterprise grows.
Today, only a few SSDs can replace dozens of high-end hard disk drives. This situation will continue, eventually reducing the total cost of data storage capacity dramatically.
As costs fall - and capacities rise - the market will experience greater usage of new-generation solid state storage media for data storage, including compact flash, MultiMediaCard, Secure Digital, Memory Stick and similar compact devices.
The future will tell if solid state technology will live up to its current claim to provide 'a thousand-fold performance increase for one-hundredth of the power consumption at one-tenth of the cost' of a traditional storage media.
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