Any time that you are going to be deploying a new backup product, there is a lot to consider. In this article, I will share with you some architectural best practices for using EMC Corp. NetWorker to back up your network servers.
One of the easiest things that you can do to increase NetWorker's performance and scalability is to add storage nodes to the network. Storage nodes are essentially secondary backup servers. What makes storage nodes so unique is that unlike traditional backup servers, administrators do not have to manage each storage node individually.
The primary (master) backup server is in charge of maintaining the backup schedule. Rather than performing all of the backups itself, the primary backup server farms some of the work out to any storage nodes that have been deployed on the network. The storage nodes provide additional processing power and throughput to the backup process, so that more data can be backed up within a given amount of time than what a single backup server could process on its own. Keep in mind that this process is not static. A storage node may not back up the same resources each time that a backup is run. NetWorker uses intelligent routing in a way that allows for the optimum use of backup resources.
Any time that you have multiple backup servers performing simultaneous backups, manageability becomes a concern. After all, if you need to restore a file, then you would typically need to know where that file was stored, and which server backed it up.
When you use storage nodes, however, this problem goes away. The primary server acts as the master backup server. Not only does it tell the storage nodes what to back up, it maintains a central index of what data has been backed up, and where. These indexes are designed to allow administrators to locate data much more quickly than they would be able to if they had to scan the backup media, or do a search across a flat file.
Tape library usage
In large enterprise environments, it is common to have to use multiple tape libraries in order to back up all of the necessary data. Even so, the backup architecture is often configured so that individual tape libraries service servers that are running specific operating systems. For instance, one tape library may service Linux servers, while another services Windows servers.
NetWorker allows tape libraries to be used in the optimal manner without regard to the type of server that is being backed up. Data is written to the tape using Open Tape Format (OTF). This allows heterogeneous data to be written to a single tape. More importantly, the use of OTF makes cross-platform migrations easier. For instance, if an organization wanted to move all of the data off of their Linux file servers and onto a Windows file server, they could just restore the Linux data directly to the Windows server, because both operating systems are able to recognize the same tape format.
Disk-based backups
Although NetWorker has the ability to back data up to tape, it is often much more efficient to perform disk-to-disk-to-tape backups. NetWorker allows you to configure one or more disk arrays to act as backup storage pools. One of the advantages of using this approach is that it makes it practical to perform snapshot backups throughout the day. At the end of the day, the more recent snapshots can be written to tape for offline storage.
I highly recommend making snapshot backups, because it allows the backups to be more current than they would be if you simply made a daily backup late at night. If you do use snapshot backups, then those snapshots are managed through a feature known as PowerSnap. PowerSnap is responsible for scheduling and creating snapshots, but it can also act as a proxy for snapshot backups. This means that if you have to restore a snapshot backup, the data is automatically restored to its original location, regardless of where the recovery operation is actually running.
Another advantage to using disk-based backups is that unlike a tape, disks support nonlinear random file access. This makes it possible to perform multiple backup operations against the same storage pool simultaneously. For example, you could restore a file at the same time that a snapshot backup is being made. You can also restore multiple backup streams simultaneously from the same pool, or even create a backup clone while another backup operation is running.
As you can see, you can easily use NetWorker to set up a simple backup server. In larger organizations, however, you have the ability to freely add storage nodes, disk-based backup pools, and multiple tape libraries. NetWorker has no trouble managing the complex relationships between these types of components and your data.
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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