Let’s talk about backup and restore for Exchange Server. I am curious about common practices among Exchange Server deployments. What are you doing to ensure your Exchange Server data is safe and sound?
Microsoft provides three main types of backup methods (four, if you count the Copy option), and many strategies exist for combining these methods depending on your goals and sensitivity to data loss. The three types of commonly used backup methods are full, incremental, and differential. Traditional thinking tells us that a full backup followed by daily incremental backups is the best course of action. The advantage of this strategy is that backup time is minimal for each daily incremental backup, because only the transaction logs (which are 5MB each) are copied to tape. However, when you have to restore with this strategy, you must restore the initial full backup tape plus every daily incremental tape. If your Exchange Server crashed Friday and you made your full backup Saturday, you would need the full backup tape plus five more tapes from the backups from Sunday through Thursday. Although completely legitimate, this strategy does have some drawbacks.
Another strategy, which doesn't require every daily backup tape since the full backup in the strategy above, would be to combine a full backup with daily differential backups. For Exchange Server, the differential backup simply copies all the transaction logs since the last full backup. Using this strategy for Exchange Server alleviates the need to pack so many tapes. When you perform a restore, you need only the full backup and the latest differential backup tapes. The disadvantage is that each daily differential backup takes longer as the week progresses, depending on the amount of transaction logs that accumulate (depending on server load) on the Exchange server.
Another strategy is the daily full backup option, which more and more Exchange deployments are using. I most often recommend this strategy to organizations I interact with. The daily full backup option is great when you want to recover an Exchange server because you only need one tape from the previous day’s full backup. The downside, however, is that a daily full backup takes more time to perform. When faced with potential loss of mission-critical messaging data, many organizations are more than willing to endure the inconvenience that daily full backups bring.
Whatever your current strategy, it's important that you consider each of the above options and how they fit into your environment. In fact, you might consider additional variants such as a daily full backup combined with a mid-day differential backup for even more data security. Also, check with disaster recovery vendors who support Microsoft Exchange Server (e.g., Computer Associates, Seagate/Veritas, Legato, and UltraBac). The strategy and vendor you select are the most important steps to ensuring disaster tolerance for your Exchange Server deployment.
