Some weeks ago, I posted this video on LinkedIn: Oracle Data Guard Switchover Changes in 23ai. The video explains the steps executed by a switchover operation in Data Guard 19c. Then, to explain the steps for 23ai, the same video sequence is repeated at 4X the speed. It was a funny and unexpected twist, but hopefully conveyed that, under some conditions, we measured such a faster role transition.
Faster role transitions imply lower RTO in case of automatic failovers and less downtime overall, which has positive effects on the business.
The following charts show how fast Oracle Data Guard 23ai role transitions are (23.8 was used) compared to Oracle Data Guard 19c (either 19.18 or 19.22 were used), according to our measurements (more details later in this article). We did that for different configurations using an increasing number of PDBs, data files, services, and RAC instances.
That can range anywhere from similar timing to more than 4X faster.
What do we measure, exactly?
We measure the time difference between entering the SWITCHOVER or FAILOVER in DGMGRL and starting the services, as seen in the alert log.
For that, we use three different configurations, as per the following table:
| Config | System |
PDBs |
Data Files |
Services |
Redo Rate |
| SMALL |
2-node Exadata RAC |
5 |
50 |
10 |
60 MB/s |
| MEDIUM |
4-node Exadata RAC |
12 |
500 |
12 |
100 MB/s |
| LARGE |
4-node Exadata RAC |
100 |
10’000 |
1200 |
100 MB/s |
In all three cases, we simulate an OLTP workload using Swingbench.
The faster transitions are the result of several bug fixes and code improvements that happened over the first few release updates of Oracle Database and Oracle Grid Infrastructure 23ai.
- Parallelization of independent tasks.
- Removal of unnecessary sleep routines or repeated checks.
- Optimizations at the Database level (RAC, Multitenant, Recovery).
- Optimizations at the Clusterware level.
Some optimizations have been backported to Oracle Database 19.27 and are visible when used in conjunction with Oracle Grid Infrastructure 23ai.
Although the numbers are for SWITCHOVER and FAILOVER, these changes benefit all role transitions, including REINSTATE and CONVERT TO SNAPSHOT|PHYSICAL STANDBY.
The impact is noticeable already in LiveLabs
We launched the new workshop “Set Up Unparalleled Data Protection with Oracle Active Data Guard 23ai” at CloudWorld 2024 and recently updated it to use OCI Base Database Services 23.7. While we were doing that, we also simplified it to make it easier to follow.
If you try it out, you can notice that even on a very small configuration, the switchover is much faster than it used to be in 23.3.
Switchover in 21 seconds in Oracle Database 23.3:
Switchover in less than 9 seconds in Oracle Database 23.7!
I’m looking forward to hearing about the improvements for YOUR databases.