Day 11: Snapshot Carousel

December 22, 2020

The Snapshot Carousel, introduced in Oracle Database 18c, provides customers a library of PDBs taken over a period of time. Customers now have access to point-in- time copies of PDBs, to use for hot cloning or restoring. Snapshot carousels are great, because it does not rely on storage snapshot technologies.

Unfortunately, as of this article, snapshot carousels are only available on the Engineered Systems (Exadata and ODAs with ACFS) platforms including Exadata Cloud services. For testing purposes, you can leverage the underscore '_exadata_feature_on' initialization parameter.

Snapshot Carousels provide point-in-time sparse or full copies of the entire pluggable database depending on the storage support for thin/sparse provisioning. You can configure snapshots to occur every day with the SNAPSHOT MODE EVERY 24 HOURS clause, or any threshold in minutes or hours. This option can be specified during the CREATE PLUGGABLE DATABASE or ALTER PLUGGABLE DATABSAE option. Acceptable thresholds for automatically creating snapshots are:

  • Every x hours – a snapshot is automatically created every “x” hours between 1 and 1999 hours.
  • Every x minutes – a snapshot is automatically created every “x” minutes between 1 and 2999 minutes.

Customers can provision clones from any given day, from any of the eight copies maintained by Oracle. As of now, the maximum number of snapshots is governed by the MAX_PDB_SNAPSHOTS parameter, which has a default value of 8 copies. When the maximum copy is reached, Oracle will drop the oldest snapshot before it provisions the next snapshot of the PDB. This allows customers to go back in time, up to 8 days (or whatever is the snapshot interval is defined to be), to provide the most current or prior snapshot images of the PDB. Some use cases for snapshot carousels are….

To receive the full article, please complete the form provided.  A pdf will be automatically emailed to you, so be sure to check your spam/junk mail if you do not see it.

    Full Name (required)

    Your Email (required)

    Company (required)

    Phone number (required)

    Job Title (required)