Data classification for ILM and DR

Computer Technology Review, Nov, 2004 by Fred Moore

Mission-critical data is used in the key business processes and can account for as much as 15% of all data stored online. Mission-critical applications represent those applications that are needed immediately to resume a business after the IT function has been disrupted. Mission-critical data is normally classified as company secret. Losing access to mission-critical data means loss of revenue, potential loss of customers and placing the survival of the business at risk. The optimal replication strategy for mission-critical data is disk mirroring since immediate recovery is mandatory at any cost. Mirroring protects against device failures but not from data corruption. Therefore, all data that is mirrored should also have point-in-time copies that enable recovery prior to the corruption event. These backup copies are most cost effectively stored on magnetic tape. Maintaining mirrored copies of mission-critical data is the key to successful hot-site strategies.

Vital data is used in normal business processes, but doesn't mandate instantaneous recovery in order for the business to remain in operation. Vital data may also be classified as company secret. Data recovery times from seconds up to a few minutes are acceptable and vital data is normally backed up using automated virtual (disk-cached) tape libraries or economy SATA-based disk arrays. Mirroring is not normally required for vital data as replication techniques such as point-in-time copy, snapshot copy and journaling are sufficient.

Sensitive data is used in normal business operations and recovery time can take minutes or hours without causing severe operational impact. With sensitive data, alternative sources for accessing or reconstructing the data exist in case of data loss. Tape has been the mainstay backup choice and potentially the new MAID storage category will provide another viable and cost-effective technology option.

Non-critical data averages about 40% of all data stored online, making it the largest classification level. Non-critical data has relatively low security requirements and duplicate copies often exist. Lost, corrupted or damaged data can be reconstructed with minimal effort and cost, and acceptable recovery times can range from hours to several days, in some cases, since this data is not essential for business survival. E-mail archives, digital records and personal data files often fit this profile.

From "Storage Navigator" by permission of Fred Moore, president of Horison Information Strategies (Boulder, CO)

www.horison.com