Tip

Tutorial on solid-state disk (SSD) devices

What you will learn: This tip outlines the pros and cons of high-speed solid-state disk (SSD) devices.

Although solid-state disk (SSD) devices typically offer access speeds 200 or so times

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faster than hard disks, so far the high price of solid-state memory has kept these devices confined to niches in the data center.

However, storage professionals are beginning to see more situations where the advantages of these high-speed storage devices, based on battery-backed DRAM or flash memory, outweigh their cost. As the technology improves and the price drops, SSD is becoming more than just a high-priced Band-Aid to be slapped on storage hot spots. SSD is now being used in applications such as transaction processing and improving storage area network (SAN) performance.

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According to flash drive and SSD maker Samsung, demand will grow from 2.2 million solid state disks last year to 173 million this year and 9 billion by 2010. Although the vast majority of these SSD devices will be used in laptops and consumer electronics products, demand for SSDs is growing for servers and other enterprise storage applications.

As prices of flash memory and RAM continue to drop, larger solid state disks are becoming economically feasible for more storage uses. As prices drop, other advantages of SSD, such as low power consumption and reliability, are playing a larger role in purchase decisions.

Not that SSD is even close to the price per gigabyte of hard disks. For example, Violin Memory Inc. sells its 1010 appliance starter kit with 128 GB of memory for around $50,000.

However, SSD manufacturers are paying more attention to usability, interoperability and management issues. Features like remote management are becoming common on solid state disks and other products are now able to work with them. For example, Microsoft's Vista is SSD-aware.

Familiarity with the technology has also helped adoption. Similar products, such as USB modules, are becoming more common in business and everyday life. It seems like every IT person has at least one thumb drive tucked into their desk these days. This exposure to solid-state storage helps eliminate some of the uncertainty about SSD by extension.

Finally, SSD consume less power. SSD typically uses much less power and produces less heat than hard disks. Violin Memory claims that its 1010 appliance uses less than one watt per gigabyte, about one tenth the power consumption of a typical hard disk.

New SSD products are emerging to enhance enterprise storage. In July, Solid Data Systems announced a 1 TB SSD array, called StorageSpire, that uses Fibre Channel to connect the SSDs. The StorageSpire array supports up to eight 4 GB Fibre Channel connections and multipath failover for higher reliability.

StorageSpire is designed as a direct replacement for a RAID array for applications like transaction processing. Traditionally, the main use of SSD in IT has been as very high-speed caches to handle hot spots, such as indexes in databases. Solid Data claims that using the product greatly reduces the size of queues and thereby increases system stability.

The prevailing wisdom is that SSD will never replace hard disk. While that's probably true, it's worth remembering that hard disk never completely replaced tape either. The real question is what the mix of SSD and hard disk will be in the storage architecture. That will most likely be determined by issues such as reliability and power consumption, as well as price.

About the author: Rick Cook specializes in writing about issues related to storage and storage management.


This was first published in September 2007

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