In tiered data storage, priority data should be stored in high-performance data storage systems. As the data value in that storage system declines or depreciates over time, it should be moved it or migrated to lower performance and lower cost storage. Migrating the data will better align its value with the cost of storing it. Also, the concept of tiered data storage makes perfect sense and most data storage administrators attempt to tier some or all of their data.
However, the use of tiered data storage is often ignored or forgotten when data backup and recovery plans are implemented into a enterprise data storage environment. In most cases, the value of an application and its data can also be applied to backup and recovery procedures. The recovery point objective (RPO) and recovery time objective (RTO) should vary for each and every application and its data, and all data should not be treated in the same way during backup and recovery procedures.
If all data were treated in the same fashion in a company's storage environment, this would mean that the mission-critical data such as online transaction processing (OLTP), email, the organization's accounting, customer resource management (CRM) and even the server images themselves would have the same backup frequency and recoverability as marketing's press releases, PowerPoint presentations, JPEGs, Word documents, or MP3s. The real problem with treating all data the same during data backup and recovery is that it either increases the risk of losing critical data, raises the total cost of data backup and recovery, or lengthens the time needed to do regular backups. All cases ignore the fact that data backup is a means to an end with the end being data recovery from a failure caused by natural or human disasters.
In one example, all data is commonly backed up once a day, put on tape, then shipped offsite. This methodology means that the RPO is 24 hours, and the RTO is a few days or longer. This is not a good idea for an organization's mission-critical data. First, the process in recovering the data takes much too long, bringing all of the correct tapes back from offsite, and then recovering them in order, (which is subject to common human error). This can be incredibly tiresome and annoying if all that is being recovered is a single file caused by an accidental deletion. Second, it assumes all data on all tapes are recoverable. In the end, both introduce unacceptable risks to mission-critical data.
On the other hand, if all data is backed up to disk, virtual tape (disk that appears like tape) or deduplicated disk, the RTO speeds up, but raises the total cost of data backup and recovery. Unfortunately, those costs will continue to increase as the amount of data continues to grow. It makes no sense to provide higher cost rapid recovery technologies for nonessential data.
Tiered backup and recovery recommendations
All organizations should tier their data backups and recoveries to reduce risk and costs. Most data backup and recovery or data protection software have the ability to provide different RPOs and RTOs for different types of data. Essential or mission-critical data should be backed up frequently for more specific RPOs. Storage administrators should also consider using continuous data protection (CDP) for their mission-critical data for the ability to roll back to any point in time in case of lost or deleted data. Furthermore, mission-critical data should be backed up more than other data while being stored locally on faster systems and media for faster RTOs, and a copy of the data should be stored offsite for disaster recovery (DR). Less critical data should be backed up less frequently (coarser grain RPO) and stored on less expensive systems and slower media (SATA disks or deduped SATA or tape for less critical data).
About the author: Marc Staimer is the founder, senior analyst, and CDS of Dragon Slayer Consulting in Beaverton, OR. The consulting practice of 11-plus years has focused in the areas of strategic planning, product development, and market development. With over 28 years of marketing, sales and business experience in infrastructure, storage, server, software, and virtualization, he's considered one of the industry's leading experts. Marc can be reached at marcstaimer@comcast.net.
