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Planning SnapVault backup schedule and Snapshot copy retention

It is important to plan the SnapVault backup schedule and number of Snapshot copies to be retained.

Before you begin

Before you start SnapVault configuration, you should create a table to plan how many Snapshot copies you want per volume, when you want them updated, and how many of each you want to keep.

For example:

  • Hourly (periodically throughout the day)

    Does the data change often enough throughout the day to make it worthwhile to create a Snapshot copy every hour, every two hours, or every four hours?

  • Nightly

    Do you want to create a Snapshot copy every night or just workday nights?

  • Weekly

    How many weekly Snapshot copies is it useful to keep?

On storage-based primary systems and SnapVault secondary systems, the data to be backed up is captured and preserved in Snapshot copies.

Steps

  1. On the Data ONTAP primary systems, plan the intervals at which to create SnapVault Snapshot copies of your primary system qtrees. The maximum frequency at which you can take Snapshot copies is 1 hour.

    Note: On primary storage platforms not running Data ONTAP, Snapshot copy planning and creation does not apply. For more information, see the Open Systems SnapVault documentation.

  2. On the SnapVault secondary system, plan the intervals at which you want to update the secondary system qtrees with data transferred from primary storage platforms, and create SnapVault Snapshot copies to retain that information.
  3. Plan how to limit the combined total of Snapshot copies retained on any one volume of the SnapVault secondary system to 255 or fewer.

    Attention: The combined total of Snapshot copies retained on each volume of the SnapVault secondary system cannot exceed 255. If the number of Snapshot copies per volume limit is reached and the old Snapshot copies are not deleted, SnapVault will not create new Snapshot copies on that volume.

Example

In this example, the user is supposed to have 12 qtrees on the secondary system volume.

Snapshot intervals Primary storage: when created Primary storage: Snapshot copies retained Secondary storage: when created Secondary storage: Snapshot copies retained
weekly sat @19 4 sat @21 8
nightly mon-fri @19 10 mon-fri @20 60
hourly @7-18 11 @8-19 120
Total n/a 21 n/a 188
On the secondary system, the user schedules the following:
  • A weekly update every Saturday at 9:00 p.m. and keeps 8 of them
  • A daily update every Monday through Friday at 8:00 p.m. and keeps 60 of them
  • An hourly update every hour from 8:00 a.m. to 7:00 p.m. and keeps 120 of them

    The result in this example is that 188 Snapshot copies are being kept in the SnapVault secondary system volume.

    The limit on Snapshot copies per volume is 251, so the 188 Snapshot copies scheduled in this example do not exceed the volume limit.

    If you need to retain more than 251 Snapshot copies on the SnapVault secondary system, you can configure additional volumes on the secondary system. Each additional volume can support 251 additional Snapshot copies.