By Franck Pachot
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A ‘Data Guard’ checkbox is available for a long time on the Oracle Public Cloud Database as a Service, but it’s only for a few days that it does something: create a service with an database in Data Guard.
I’ve created a database service as usual and the only additional thing I did is to check ‘Standby Database with Data Guard’:
Here are the attributes:
And the creation starts. But in the progress message, you see two VMs:
If you go to the Compute services, only one service is there, the first VM:
But back to Database services, when you click on the service, you see the two nodes:
It’s a full Data Guard configuration, with the broker automatically configured.
The latency is one millisecond on average which is very good and allows the standby to be in SYNC. Here are some wait events with 4000 small transactions per second (2MB redo per second):
Wait Event Histogram DB/Inst: CDB/CDB Snaps: 42-43
-> Total Waits - units: K is 1000, M is 1000000, G is 1000000000
-> % of Waits - column heading: <=1s is truly 1s is truly >=1024ms
-> % of Waits - value: .0 indicates value was Ordered by Event (idle events last)
Total ----------------- % of Waits ------------------
Event Waits <1ms <2ms <4ms <8ms <16ms <32ms 1s
-------------------------- ----- ----- ----- ----- ----- ----- ----- ----- -----
LGWR wait for redo copy 100K 99.1 .9 .1 .0 .0
LNS wait on LGWR 110K 100.0
Redo Transport MISC 110K 42.2 55.7 1.4 .5 .2 .0 .0
Redo Writer Remote Sync No 110K 100.0 .0 .0
SYNC Remote Write 110K 58.9 39.1 1.4 .4 .1 .0 .0
log file parallel write 332K 97.7 1.7 .3 .1 .1 .0 .0
log file sync 1552K 13.7 46.8 35.8 3.1 .5 .1 .0
-------------------------------------------------------------
Note that if you are not in Extreme Performance edition, you should take care not to open the standby or Active Data Guard usage will be recorded. On service startup, Oracle manages that with the following:
/etc/rc.d/rc.local run /home/oracle/dbsetup.sh which run dbstart (so the standby is open read only)
then it: shutdown abort and startup mount
then if it is Extreme Performance it open read only
Finally, if you wonder how the edition is checked, it’s from the service attributes available from 192.0.0.192:
[oracle@opccdb ~]$ links -dump http://192.0.0.192/latest/attributes/bundle
extreme-perf
As it is a managed database, you can Switchover, Failover and Reinstate from Cloud My Services interface: