This feature, focusing on the top three enterprise backup programs, first appeared in the April issue of Storage magazine.
With disk-based backup playing a growing role in the data center, the three major enterprise backup programs -- from EMC IBM and Symantec -- are undergoing radical changes. As disk rapidly becomes the preferred initial backup target, vendors of the three big backup programs -- EMC Corp.'s NetWorker, IBM Corp.'s Tivoli Storage Manager (TSM) and Symantec Corp.'s Veritas NetBackup -- are scrambling to enhance and change the focus of their programs. Never before has a shift of such titanic proportions affected the product development of these three dominant players which, until now, have been slow to change.
- Increasing their support for faster backups and recoveries
- Enhancing support for encrypted data
- Offering better ways to protect remote offices
Backing up to disk dramatically improves backup times, usually in the 30% to 50% range or greater. Aaron Mathes, chief operations officer for information services at Liberty University in Lynchburg, VA, finds that disk-based backup provides him with a higher degree of confidence that his backups are completing successfully. "Disk has had an exponential impact," he says, adding that he backs up 90% of Liberty University's 4TB of data to a disk cache. The EMC, IBM and Symantec products all include the ability to manage a disk cache (it's an optional feature for NetWorker), a disk volume where data is initially parked before being moved to tape. Disk caches can be shared drives on an Ethernet network or a Fibre Channel (FC) SAN drive owned by the backup server. When using a disk cache it's important to:
- Select volumes large enough for each server to keep a week's to a month's worth of backups online to expedite recoveries. NetWorker 7.3 has a wizard that assesses the size of each server's backup and required retention period, and helps administrators select a disk volume large enough to meet those requirements.
- Determine what copies of the disk backup need to be written to tape and when. For instance, if a server does incremental daily backups and full weekly backups to the disk cache, you may opt to copy only the full weekly backups to tape to conserve tape and schedule the copies during low-traffic backup times to lessen their impact.
- Use a watermark, which deletes or transfers backups from the disk cache when a certain level is reached, for example, 90% of disk capacity.
An offshoot of the growth of disk-based backup is the increased interest in backup and recovery technologies such as CDP and snapshots. NetWorker and TSM offer snapshot and replication options that support primarily array and virtualization technologies sold by their respective companies. TSM lets users execute instant restores and backups using IBM's TotalStorage DS6000 and DS8000 storage arrays or SAN Volume Controller (SVC). Similarly, EMC's NetWorker PowerSnap modules integrate predominantly with EMC's Symmetrix and Clariion storage arrays. Prior to EMC's acquisition of Legato, NetWorker offered PowerSnap modules that supported older IBM and Sun storage array models; going forward, the PowerSnap modules won't be upgraded to support non-EMC storage arrays. With NetBackup 6.0, Symantec introduced Advanced Client, which allows the central management console to identify the host-, network- or array-based snapshot options available to the client server. It also grants the storage administrator the ability to remotely configure snapshots on that server. But don't assume a backup program containing a wizard-like snapshot option will work out of the box. There are a number of tasks required to get some wizards to work in complicated storage environments. For instance, NetWorker PowerSnap modules are licensed by specific storage devices, so a future storage array change requires changing the host software and licensing. If you're using a Clariion, you must first verify that it has up-to-date firmware; because Clariion supports two snapshot methods, you must then choose the type of snapshot to use -- copy on write or split mirror. The next step is to verify that the Clariion contains sufficient storage space for the desired type of snapshot. Finally, you must install EMC's Navisphere Host Agent, Navisphere CLI, PowerPath and NetWorker client software on the host before a snapshot is created. While these steps vary in complexity according to the backup software product, both TSM's and NetBackup's snapshot modules require similar steps. McLeavy decided not to use snapshot modules. Instead, McLeavy scripts snapshots using SYMCLI commands because NetWorker didn't offer a PowerSnap module for the Tru64 operating systems he used at the time. While McLeavy is now moving from Tru64 to AIX, he still has no plans to purchase the PowerSnap Symmetrix modules because "the modules are a little pricey, considering we already have a working configuration." Click here for Page 2.