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Storage Made Easy

Can hierarchical storage management break your backup logjam?

Backup is what an agency must do for data that it knows will change. But for the vast majority of an agency's stored data, there are typically no changes — or even access.

To save resources, an agency ought to archive that static data and never back it up again. Backing it up repeatedly wastes time and media at best and can cause backups to fail to complete in the time allotted to them at worst.

By using hierarchical storage management, an agency can separate its data backup process from its archiving process. HSM may not have all the glamour of information life cycle management (ILM), but modern HSM is simple, available and surprisingly beneficial and efficient.

Detractors have called ILM "HSM on steroids" and derided ILM as simply marketing hype — nothing more than HSM dressed in new clothing. But there are important differences between HSM and ILM in both functionality and purpose. There are two easy ways to distinguish these data storage approaches from each other:

• If it's automatic, driven by an algorithm with a few parameters, such as "days since last access," it's HSM.

• If it requires careful data classification, perhaps using special software, it's ILM.

Used well, both can save money. But according to a recent survey by the Storage Networking Industry Association of its End User Committee, ILM is used mainly to support or enforce compliance with data retention, availability and data privacy regulations, not to save money. Because of the rigorous data classification it requires, ILM savings are typically long-term.

HSM is not a compliance tool like ILM. For example, ILM can immutably archive e-mail online as first received and move it offline later. HSM archives only after its specified time parameter — that "days since last access" example. But implementing ILM is viewed as a new IT storage administration pain point, while HSM is comparatively simple to deploy. HSM can save money quickly by making the backup process more efficient, lessening backup media use and freeing up storage capacity.

Buying Tips

If you're buying an HSM application, here are four things to look for:

• Quick, easy and foolproof installation and deployment. Get references from prospective vendors and check them out, and also ask around to find users the vendor hasn't provided on its reference list.

• Migration transparency. Users and applications don't like "file not found" search responses, so the HSM application you select should provide access stubs that automatically link to the migrated content.

Users and applications won't experience intolerable delays to access content that has been migrated to archival storage systems if it's available online (low-cost disks) or near-line (optical jukeboxes or automated tape libraries).

• Restoration choice. Based on the agency's needs and/or policies, the IT team must determine whether it wants the HSM tool to let users or only a systems administrator restore migrated content.

If the agency is going to enforce immutable archives, only the sysadmin should have this authority, while the end users have read-only privileges.

• Seamless integration with backup software. The backup software needs to know where content is kept. If the archived content is moved to offline or off-site storage, its media management components must know how to track restored data.

Not Your Father's HSM

Don't dismiss HSM as an outdated precursor to ILM. This storage management approach and available tools have matured. The original developers of HSM designed it to migrate data from costly online disk storage to inexpensive offline tape storage. In its earliest versions, the migration was not transparent to users or applications and was usually based on a single time-since-last-accessed parameter.

Current HSM apps are more flexible, chiefly because developers recognized greater cost savings can accrue from reducing storage management costs rather than from simply saving on the one-time storage cost itself. The software now generally allows migrations based on several parameters and can migrate data while preserving user and application access.

Agencies that need a quick, painless way to reduce storage costs and improve backup results should consider HSM. In one fell swoop, an organization can automatically migrate no-longer-accessed files from high-cost primary storage systems, slashing backup time and media usage. On storage area networks, HSM can free up most expensive disk array space. For agencies using server-attached storage, freeing up individual server storage might mean avoiding server upgrades.

The Army Corps of Engineers' New England District office is leveraging a digitizing and archiving project to apply HSM. The office hired CommVault of Oceanport, N.J., as its backup vendor about two years ago and opted to add HSM to support a special digital archiving project, says Timothy R. Winter, chief of information management. His corps office is digitizing file drawers full of environmental Superfund documents and then archiving the data.

The New England District uses disk storage and also has an automated tape library. Winter says he intends to archive the newly digitized data directly to these media so it can dedicate its SAN storage — 5 terabytes, of which 3.2 are available — to live files. Because of some advanced parameter choices in the CommVault HSM software, the new content can be archived immediately; the corps has also set last-accessed parameters for automatically moving files off its SAN. Winter likes the fact that users will continue to see the content in Windows Explorer and be able to access read-only copies from the lower-tier disk and tape storage on their own.

CommVault is just one option. CaminoSoft of Westlake Village, Calif., specializes in HSM for Novell and Windows systems; IBM makes Tivoli Storage Manager for Space Management. Plus, many backup and storage products have HSM modules.

Be the Hero

HSM can make an agency's IT chief a hero by reclaiming storage assets and extending the useful lives of the storage subsystems. Additionally, an agency can put money that might have been spent on storage acquisitions back into the budget for better use. HSM can also get an agency out of a backup bind, which will definitely make IT officials heroes when data recovery is necessary.

Dec 31 2009

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