NetBackup Snapshot Client Terminology Explained
Recently one of the fans of NetBackup on Facebook asked a question. Although his questions were specific to the difference between Snapshot client backup and regular backups, I thought it might be better to explain this in a blog and post this for the benefits of newer NetBackup Administrators.
NetBackup Client: The client side of NetBackup software on the system being protected. Its role is read from disk; send data to backup storage and metadata to backup catalog.
NetBackup Snapshot Client: The feature on NetBackup client that takes snapshot of file system state or application prior to performing backups. On UNIX/Linux platforms, this operation requires a specific policy attribute to be turned on to use this feature. On Windows, this feature is automatically enabled to make use of Windows’ Volume Shadow Copy Service (VSS).
What is the value of Snapshot Client over regular NetBackup client?
On UNIX/Linux platforms, Snapshot Client feature enables you to take the snapshot of supported file systems prior to taking backups. You also have the ability to offload the backup to an alternate client or media server when making use of this feature.
On Windows platforms, Windows VSS integration already provides the ability to take the snapshot even when Snapshot client attribute is not turned on in the policy. Hence the primary advantage of using Snapshot client on Windows is to offload the backup to an alternate client (that can also be a media server).
FlashBackup: FlashBackup is a backup method (based on Symantec’s patented technology) that provides the performance advantage of backing up the raw device while providing you the flexibility to restore individual files from the raw device backup. Note that traditional raw device/partition backups require you to restore the entire partition. In FlashBackup, the file system structure and metadata is indexed using a patented technology after which the entire device is read in raw mode.
Is FlashBackup a Snapshot Client feature?
Yes, FlashBackup is a feature of Snapshot Client. However, you may not need to specifically turn on Snapshot Client attribute in the policy because the use of snapshots is implied when you set your policy type to FlashBackup. The default Snapshot method for the file system (e.g. VSS for Windows, nbu_snap for Solaris, vxfs_snap for HP-UX etc.) is chosen with FlashBackup, but you do have the option to override it in the policy.
How about VMware/HyperV policy type?
These are also special cases of Snapshot Client where FlashBackup technology is enhanced further (there is a set of technologies under the umbrella named Symantec V-Ray) to provide agentless backups of virtual machines from an offhost system. The inner-workings of Symantec V-Ray are covered in this blog series.
Do you have questions or clarifications on terminology? Engage with NetBackup on Facebook/Twitter and we may post a detailed response here in Connect.