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Managing data storage capacity on RAID

What you'll learn: As the size of data stores continue to grow rapidly, the challenge of managing data storage capacity on RAID is increasing. While this raises some questions about the integrity of RAID, new technologies are emerging with higher capacities and more capable drives.

Managing increasing amounts of

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data storage capacity on RAID has become a difficult task for many storage administrators. The massive amounts of capacity on a single drive also raise questions about the efficacy of RAID 5 as a data protection technique. For industry analyst Mike Karp, the growing capacity of multiple terabyte disk drives inevitably increases disk errors. "For every unit of capacity, we know there will be a certain number of errors," he said.

Organizations traditionally relied on RAID 5 to overcome those errors through the use of parity data. However, because of the time it takes a system to rebuild a 1 TB drive using RAID 5, the likelihood that another drive may fail increases, compounding the problems. Karp's solution is object-based RAID, which relies on small units of storage and allows the system to rebuild the drive in smaller increments. Others suggest RAID variations that use multiple parity disks, such as RAID 6, can do the job. There are also a handful of new technologies emerging to address the capacity issues of data storage media.

New technologies increase disk's data storage capacity

Several technologies are vying to produce the next breakthrough in packing more bits on a piece of storage media. Currently, perpendicular magnetic recording (PMR), which stacks bits vertically on the surface rather than laid out horizontally, is the technology of choice, but it will hit the superparamagnetic limit within a few years. But alternative technologies are emerging, including:

  • Bit-patterned media (BPM) stores each bit as a nanometer-scale pattern of grains on the media. As described by Hitachi, it creates an ordered array of highly uniform islands, each island capable of storing an individual bit.

  • Heat-assisted magnetic recording (HAMR) uses heat to stabilize the tiny stored bits, allowing smaller bits to be recorded. HAMR, however, creates heat, which runs counter to the industry's growing green storage impulses.

  • Microwave-assisted magnetic recording (MAMR) writes bits at different layers of the media.

HAMR will likely be ready for production by 2013, with MAMR probably ready a year later, according to Mark Nossokoff, a senior member of the strategic planning team at LSI Corp.'s Engenio Storage Group.

BIO Alan Radding is a freelance writer and frequent contributor to Storage magazine and SearchStorage.com.

This was first published in June 2010

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