Back up only what you have to
Most organizations that use tape-based backup rely on incremental or differential backups as a way of decreasing their backup times. Both types of backups only back up the data that has been modified since the last full backup was made. Although such backups can go a long way toward decreasing backup times, there are problems with them.
Both incremental and differential backups require that you occasionally perform a full backup. Depending on how much data you have and your backup infrastructure, the full backup can take a long time to complete. For example, I know of one organization that starts their full backup on Friday night, but the backup doesn't actually complete until sometime on Sunday afternoon.
One way to streamline your full backups and reduce backup windows is to be selective about what you back up. For instance, finance records that you have from 2007 probably haven't changed in years. Do you really need to include them in every full backup? Sure, they are important, but why not create a permanent backup of them and then exclude the records from all future backups? By identifying and excluding data that never changes, you can reduce the amount of time that it takes to make a full backup.
Be aware of server maintenance cycles
Administrators often configure backups to run late at night when the network isn't as busy. Even though this probably seems like a good idea, some software manufacturers also try to take advantage of the late night lull in activity.
One of the best examples of this is the Exchange Server maintenance cycle. Every night, Exchange Server performs a number of automated maintenance tasks. Some of these tasks include checking the Active Directory for deleted mailboxes, processing messages that have exceeded the retention period and performing a defragmentation of the various databases.
By default, the maintenance cycle starts at 1:00 a.m. and runs until 5:00 a.m. If you are in the habit of backing up your servers late at night, then the maintenance cycle will most likely overlap with your backup.
The nightly maintenance cycle and the backup can run at the same time, but they are both disk-intensive operations. Running both at the same time can cause the operations to take longer to complete. My advice is to schedule the backup and the maintenance cycle in a way that keeps them from overlapping any more than necessary.
There are many other server applications besides Exchange Server that perform late-night, disk-intensive operations. Such operations often include the defragmentation or re-indexing of databases. Make sure to review the applications that are running on your servers to see which have nightly maintenance cycles so that you can schedule your backups accordingly.
Remember the limitations of physical storage
Server virtualization is becoming more popular, but I've seen quite a few organizations that didn't adjust their backup schedules after virtualizing their servers. This is a critical step.
Multiple virtual machines (VMs) may share a single storage array, even if each VM uses a separate volume on that array. So if multiple virtual machines are backed up in parallel, then the backup operation may place an excessive load on the storage array, greatly impacting the efficiency of the backup operation. Similarly, I have seen other situations in which multiple virtual servers shared a single physical NIC, and multiple parallel backups resulted in a network bottleneck at that NIC.
There is nothing wrong with running parallel backups in a virtualized data center. But be sure to structure your backups so that they don't simultaneously impact the same physical resources.
As you can see, there are a number of different techniques that you can use to reduce your backup windows. The key is to back up only what is necessary and to structure your backups to prevent them from competing with other processes for server disk resources. Additionally, if you are willing to spend some money, you can further optimize your backups by investing in a continuous data protection solution or a data deduplication product.
About the author: Brien M. Posey, MCSE, has previously received Microsoft's MVP award for Exchange Server, Windows Server and Internet Information Server (IIS). Brien has served as CIO for a nationwide chain of hospitals and was once responsible for the Department of Information Management at Fort Knox. You can visit Brien's personal website at www.brienposey.com.
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