Shall I shut_down DBs before Linux reboot..

Commonly, the normal shutdown process runs the stop scripts in reverse order from the start ones.
I.e. A process started last, is stopped first on shutdown.

With that said it shoukd be already setup. Double check, confirm that.

You could initiate and stop db, then issue a shutdown.

The shutdown process includes a timeout period after which the system will stop waiting for a process to stop, and Will hard term it.

If the patch team applies patches to Oracle it would be wise to first shutdown oracle in an orderly fashion, then patch and then either verify startup of oracle or reboot.  If the patches are not applied to Oracle then arnolds comment is correct.

What I normally do is run this command in oracle. I do not stop db and then shutdown
SYS> Shutdown immediate;

It take a minute or two for DB to shutdown.

If I understand the comments above, a Linux reboot may or may not shutdown oracle cleanly depending on how long it takes for oracle to respond to Linux kill command. In conclusion, it is always necessary to do a shutdown of databases/instances before Linux reboot.

Correct?

Tcheck the sysv start process.usually, the stop process reverses the start.

Often the script is from oracle. So it might issue the same shutdown db event.

Many excellent answers. Did EE change their points policy to accept multiple answers?


Do you also do this manually all the time meaning do you shutdown the DBs n weekend before patching and then restart it after the unix patches applied? I was thinking there might be a scheduler or cron job to automate this process on weekends.

You pick one comment as best solution, while others as assisted solutions. At the bottom, an option to go to the next step when all the assisted and the bestsolutions you choose ......

>>Do you also do this manually all the time meaning do you shutdown the DBs n weekend

It is scripted in the OS rc scripts.  If you installed Oracle correctly, the scripts should have been done for you.

You don't mention what Linux flavor you are using but look around for RC scripts.

It is RHEL 7.4. Oracle 12.2 has a script/cron job to schedule shutdown and startup for database?

Read up on RC scripts:
https://www.thegeekdiary.com/understanding-the-rc-scripts-in-linux/

Specific to RHEL:
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/5/html/installation_guide/s1-boot-init-shutdown-process

>>has a script/cron job to schedule shutdown and startup for database?

If you installed Oracle correctly, the scripts should be there.

Personally, I would not schedule db shutdown, updates, etc.
Sensitive systems such as databases, IMHO, should be updated manually.
Create backup, run update server (shutdown db if applicable) on complete startup db, make sure all us functional as expected done.

In a scheduled unattended, if there is a partial issue of any kind, after enough time has passed, the db will be started such that your discovery of an issue later on.if you have to address data. Incongruity .

Thank you all. Many excellent solutions. wish i can select multiple solutions as before.

Excellent comments from experts!

>>wish i can select multiple solutions as before.

You can.  Just select the "This is the solution" at the bottom of the post or posts you want.

sorry I did not realize that I can select multiple posts as "Yes this is my solution". is this correct?

I cannot say what is correct or not.  It is your question to award points as you see fit.