When it comes to database platforms Oracle is known for having one of the most scalable and resilient solutions which is why so many businesses use its software. Most large businesses will use features such as Oracle RAC and Data Guard to achieve their uptime target, recovery time objective (RTO) and recovery point objective (RPO). These features however, as of 19c, are only available in Enterprise edition so what are the options for standard edition?
High availability typically focuses on uptime and keeping operations running with minimal disruption. High availability is typically delivered using redundant components across servers, storage, networks and application level clustering.
Disaster recovery on the other hand focuses on the ability to recover from a disaster quickly and efficiently, typically after a period of downtime. Disaster recovery is typically delivered through additional copies of the data whether those exist in the form of a backup or a replicated copy in a standby facility.
Whilst almost every company will have a disaster recovery solution, significantly less have a high availability solution, typically coming down to what the function of the database is, who it serves and the tolerance for downtime.
The primary high availability option for Oracle Database Standard Edition is Standard Edition High Availability. This is included in the licence however requires that you licence both of the nodes that Oracle may run on. SE HE provides a warm standby that can take over from the primary node in the event of a planned or unplanned event.
SE HA is considered an application level clustering option which should typically be the first option you should consider when looking at any high availability solution. Application level clustering usually performs the best and provides the best crash consistent outcome.
Another option that could be used if you are running Oracle within a virtual machine is replication of the virtual machine itself. This again requires that Oracle is licensed on both the nodes it could run on and typically you will need to licence the hardware of the hyper-visor and not the virtual machine.
Virtual machine replication however has its downsides. During a planned failover the virtual machine is shut down cleanly and there are generally not any issues. During an unplanned failover however, the database is not shut cleanly and will require redo logs to be replayed on database startup. Whilst Oracle does generally do a good job of recovering from an unclean shutdown, it is not as consistent as using SE HA.
Finally, third party solutions such as DBVisit Standby could be used to provide a warm standby without using the native Oracle functions. DBVisit Standby is particularly good if you are not familiar with configuring SE HA as it provides a very simple installation and configuration process. DBVisit works with log replication in a similar manner to SE HA, also providing automated failover but most importantly is much more configurable than SE HA and provides a control element with monitoring and alerting of the health of the environment.
DBVisit Standby is also supported across multiple geographic regions where SE HA is not.
If you wish to create a disaster recovery solution without any additional licensing or third party tools the simplest method is to use Oracle RMAN to create your backups. This typically requires a few scripts setting up on the server and a cronjob to run them. RMAN is capable of full and incremental backups which should be stored on another server away from the primary.
Another option is third party backup software such as Veeam which in its enterprise plus version has support for Oracle databases either through the native agent or as a virtual tape device which can be used within RMAN. The advantage of using Veeam is that it will allow easier setup, monitoring and maintenance of the backup jobs. Veeam also provides a very simple recovery process to the original or a new database server. Point in time recovery is also possible if archiving is enabled on the database.
Finally, if you have DBVisit Standby to provide high availability to your database then there are some functions such as lagged copies which can be used to allow some disaster recovery options as well. Lagged copies work by receiving a copy of the archived redo logs straight away but they are not applied to the database until a set period after which they are created.
As an example, this may not apply to the logs until 6 hours after they are created. The logs can then be re-played up to any point specified before opening the database in the event of a recovery.
DBVisit standby is also a great option if you wish to geographically segregate your primary and standby.
Between Oracle native options and third party providers there are a wealth of high availability and disaster recovery options for Oracle database standard edition. Each has its own pros and cons, typically with third party solutions bringing a substantial amount of value add over the native options.
Vinters are an Oracle, DBVisit and Veeam partner and can assist in the design and deployment of a multitude of solutions to fit each business’s unique needs. Contact us using the form below to speak to one of our design consultants for oracle database hosting and disaster recovery solutions.
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