The case for CAS

MANOJ CHUGH on the many advantages of Content Addressed Storage

UNTIL NOW, the industry-wide embrace of storage networking and the rapid coupling of countless petabytes of data have shaped conventional storage thinking in two fundamental ways. One, storage improvements must always be faster and cheaper. Two, complexity must be tolerated to achieve efficiency.

Such thinking is rooted in the build-out process that evolved storage networks to where they are today—at the epicentre of a company’s business. But new challenges posed by Web-based service models, increasing regulatory requirements, heightened security, data preservation and storage optimisation are ushering out old thinking, and bringing to light the value of an architecture called Content Addressed Storage, or CAS.

CAS is key to business because it overcomes the threats posed by these new storage challenges—the unmanaged, exponential growth in capacity and the number of fixed content objects.

By the end of next year, most of the data stored by every corporation and the entire US government combined will be fixed content. Any file requiring storage that isn’t changed, updated, or modified when recalled is essentially fixed content. For example, legal and securities documents, photographic archives, medical imaging files, product and promotional shots, consumer check images, media presentations, transit maps—and even instant messages. The daily flow of business, along with increasing regulations requiring businesses to store documents for a certain number of years, means fixed content can quickly become an 800-pound gorilla on the back of a company’s storage budget.

New category

When organisations have looked for fixed content storage solutions they’ve faced a dilemma: what they need versus what the storage industry provided, which was complicated by the judgement of the value of the information as a result of the cost compared to the frequency of use. For example, the frequency of using information such as check images, contracts or e-mail usually diminishes as it ages. However, when the information is needed, the speed of access can be the defining factor in an organisation’s ability to take full advantage of a business opportunity. Until CAS, organisations had to make a hard choice between the speed of information access (provided by magnetic disk storage solutions) and assured content authenticity (provided by optical technology). Tape technology, the choice of some, is considered the least functional or least-cost option.

CAS is a new category of storage. It provides the online performance of magnetic disk because it is a magnetic disk, and assures content authenticity equal to or better than optical technology at a total cost of ownership equal to or better than that of a tape library. It offers more functionality for a lesser cost. Everything needed and wanted for fixed content is in one solution, which compares favourably with today’s scenario of cobbling together dissimilar technologies. With CAS, an organisation’s fixed content is cost-effectively available online, 24/7, with assured authenticity.

One copy is enough

How unmanaged fixed content can savage an intelligent storage network’s resources can be seen with an e-mail. If a CEO sends a company-wide e-mail to 60,000 employees about new travel guidelines, it is likely to be indefinitely stored on and routinely viewed from a server or a PC drive. As a matter of convenience, employees may save the e-mail for reference. For storage administrators, that e-mail message is now taking up 59,000-times more disk space than necessary. And, because everyone is in possession of a copy of the original message, the risk increases that its contents could be tampered with and forwarded to outsiders.

With CAS, instead of sending out thousands of e-mails, an original document can be created and stored in the CAS repository along with a digital ‘claim check’ so pointers or links can be sent to direct authorised employees to the original. The increased efficiency of storage in a CAS-enabled environment is thus evident; the optimisation of storage resources by CAS becomes even greater when that relatively small e-mail is replaced by a large multimedia corporate sales presentation stored and recalled nearly every day.

Regulatory requirements

Take this same model of CAS efficiency and apply it to securities documents and medical records. Here, the business role of CAS in ensuring the retention, preservation and authentication of data in a federally-regulated environment becomes even more pertinent. The number and type of federal regulations governing business records and other data is on the rise. Whether it is

the amended Securities and Exchange Commission Act of 1934, Rule 17a-4 (which requires investment records to be retained for anywhere from five to seven years), the Health Insurance Portability and Accountability Act (which addresses the storage and security of health information), or a matter of national security, companies that cannot produce an unmodified original document can face expensive legal action.

On the technology front, advances in disk drives have fostered the role of CAS within businesses. Companies that once stored digitally-archived records on tape libraries or older WORM (write-once-read-many) optical drives can now take advantage of cutting-edge ATA in CAS arrays. CAS uses ATA disk technology, but that is where comparisons to conventional ATA disk arrays end. It is the features of CAS’ extensive software layer that fortify its business advantage by adding peace of mind when it comes to preserving fixed content that absolutely must not be corrupted. Just imagine pulling out a digitally-archived MRI for use as defence evidence in a medical malpractice suit, then suddenly discovering that the data has degraded to the point where a dark spot has appeared on the body image—a spot that wasn’t there before.

Breaking away

When the reputation and future of a business is on the line, just focusing on the speed and initial acquisition price of a storage technology is not the answer. Major corporate players who understand this, are investing in CAS now, and realise that it pays dividends in three significant ways.

First, by optimising storage capacity and streamlining data retrieval though object-based storage, not complex logical-volume file systems. Second, by ensuring retention, preservation and authentication of data. Third, by integrating seamlessly and easily with a company’s existing storage area network (SAN) and network attached storage (NAS) architectures.

CAS breaks away from conventional thinking about storage by offering all these three benefits, and more, in what is perhaps one of the simplest storage architectures ever designed. Its arrays attach directly to a company’s IP-based Ethernet, so no changes are required to the company’s existing SAN and NAS design to accommodate a CAS array. By operating independently from its place on the Ethernet, a CAS array can serve files to authorised clients without complicating the software-based management of other storage arrays.

CAS arrays also manage the allocation and location of stored object files internally as a self-managed process. This further simplifies the storage administrator’s task by eliminating the need for complex storage application integration, while simultaneously providing a secure, autonomous and scalable reciprocal for fixed content within the overall storage network—a money-saving proposition. CAS ‘claim checks’ are digital fingerprints derived uniquely from the object itself to create a distinct ‘content address.’ This one-of-a-kind content address, along with the fact that fixed content is stored as an object file, means users are not retrieving logical file volumes of potential duplicate files based on file name or other search criteria. Instead, users retrieve the actual original document as it was first placed on the CAS.

Almost unhackable

Keeping fixed content in step with related applications is done using technology called a content descriptor file, which contains time-stamp information, application-specific meta data, and the content address of the fixed content. These features simplify CAS management so that storage administrators do not have to worry about file system hierarchies which can drain performance when extended beyond set boundaries. They also enable the application of specific policies regarding how long certain fixed content should be saved and when it should be deleted. This reduces the management burden for storage administrators by way of intelligent automation.

Many types of data that fall under the definition of fixed content are highly regulated or sensitive in nature, such as medical images, patient records and financial information. This often moves the requirements for confidentiality and security to the forefront of the discussion. The good news is that CAS arrays are virtually unhackable—period. With CAS, authorisation is maintained at the claim-check level and the system’s way of relating fixed content to its user application adds an extra layer of security above and beyond access codes and passwords. Advanced CAS arrays can deny user access by the very application being used to call up the fixed content. With this ability, certain content stored on a CAS array can be used exclusively by departments running their own applications, while the CAS array continues to serve content to other departments and the World Wide Web as a whole.

Manoj Chugh is the president of EMC (India and SAARC)