Creating policies is a great way to automate the management of your datasets. Whether you are setting policy for syncing data or snapshotting or refreshing virtual databases, policies ensure that your data will be ready when you need it.
In order to create policies, navigate to the ‘Manage’ dropdown and select ‘Policies’.
There are four categories of policies that the Delphix Engine uses in conjunction with datasets objects:
- SnapSync – How often snapshots of a source database are taken for a dSource
- VDB Snapshot – How often snapshots are taken of the virtual database (VDB)
- Retention – How long snapshots and log files are retained for dSources and VDBs
- VDB Refresh – Automatic refresh of a VDB either with the most recent snapshot or latest Timeflow logs. The default setting for this policy is None.
Avoid Adding Conflicting Policies
The following example case can occur if the Snapshot policy is set to NONE, this has a direct impact on the retention policy and potential VDB data growth: An engine encountered a domain0 space issue that resulted from the archive logs for a single VDB taking up 25% of the pool. That engine was set to use a ‘None’ Snapshot policy along with a 1-week log retention policy. Because the archive logs were needed to provision from the one and only snapshot that existed, the engine was unable to enforce the retention policy.
There can be default or custom policies for each of these categories.
Default policies exist at the domain level and are applied across all objects in a category.
You can modify the settings for a default policy in a category, but you cannot change the names of the default policies.
Custom policies allow you to create unique policies to fit your own schedule’s requirements. These can be set up with varying time intervals, ranging from minutes to days.
Setting Different Policies for Objects in a Group
Policies applied at the group level will affect all objects in that group. If you want to set different policies for objects in a group, apply the policies at the group level first, then apply policies at the object level.
SnapSync policies determine how often snapshots are taken of the source database.
In the Default SnapSync policy, a snapshot is taken daily at 3:30 AM local time and will cancel if not completed within four hours. If SnapSync does not complete within this four hour period, it will resume at the next scheduled daily time, until the process is complete.
Click the Edit icon to change the Default SnapSync policy, or click the Add icon to create a new SnapSync policy.
Policies may be configured using the provided Schedule date picker, by Interval, or by using a Quartz cron expression by selecting Custom.
Retention policies define how long the Delphix Engine retains snapshots and log files to which you can rewind or provision objects from past points in time. The retention time for snapshots must be equal to, or longer than, the retention time for logs.
To support longer retention times, you may need to allocate more storage to the Delphix Engine. The retention policy – in combination with the SnapSync policy – can have a significant impact on the performance and storage consumption of the Delphix Engine.
Benefits of Longer Retention
With increased retention time for snapshots and logs, you allow a longer (older) rollback period for your data.
Common use cases for longer retention include:
- SOX compliance
- Frequent application changes and development
- Caution and controlled progression of data
- Reduction of project risk
- Speed of rollback or restoring to older points in time
You can customize the retention policy to retain snapshots and logs for longer periods, enabling usage to specific points further back in time.