This topic describes basic concepts behind the creation of dSources from DB2 instances.
Instance Level Operation
Delphix DB2 Instances
Delphix operates on the instance level and requires that
- the staging and target hosts must have the empty instances created prior to Delphix using them, and
- the instance owners are added as environment users
It is important to note that our dSources and VDBs are entire instances and NOT specific databases inside an instance.
DB2 for Delphix ingests data by using a Standby instance of DB2 to create the necessary data files that represent the data. This Standby instance is converted to a Delphix dSource by going through the linking process during which it is given access to a full backup of each of the databases that are to be added to the dSource. Delphix then runs an automated redirected restore process on the backup file in order to convert the data files to a format and structure that is compatible with Delphix. All of the data files and log files from this backup are stored on a single NFS mount created by the Delphix engine which allows it to snapshot the dSource as necessary.
A single standby instance can contain data from multiple source databases.
During the linking process, you can optionally setup an HADR connection between the original source databases and copies on the Standby instance. By doing this the Standby instance will always keep its databases in sync with the source databases using HADR for log shipping. It is important to note that a single Standby instance (dSource) can contain multiple databases from multiple different servers and instances as long as each database has a unique name.
Delphix HADR standby maintains a different structure from the production server and should never be used as a DR failover from production.
Virtual Instance (VDB) Provisioning
The provisioning process in DB2 for Delphix converts an empty DB2 instance on the target host into a virtual instance (also known as VDB) that contains the same databases as the dSource. After provisioning, the data in the Virtual instance will be an independent writeable copy of the dSource snapshot. Once a VDB has been provisioned to a target environment, you can also implement a snapshot policy for that VDB, to capture changes within it as if it were any other logical or physical database. It is also possible to provision a VDB from a snapshot of another VDB.
A single DB2 instance can only be used for a single VDB or dSource. If you wish to create multiple copies of a VDB on a single host you will have to pre-create the empty DB2 instances to provision data into.