Is it ok to restart DB without starting CI and Application server?

[Former Member]

Hi,

I have a BI 7.I with 2 apps server in my landscape. I have restarted my oracle database without stopping CI and apps.

After DB restart I have checked my system and everything looks good to me. All the data loads jobs are running on time and I am not seeing any kind of performance issue with the system.

I need to know what SAP best practice is like do I need to restart CI and Apps also for restarting the DB.

Please provide your feedback.

Thanks & Regards,

Vaibhav Srivastava

Edited by: vaibhav421in on Mar 8, 2011 2:57 AM

[Former Member]

Here my answer is always follow the standard process to avoid integration/interface issues.

But in this situation this is abnormal (As told by you), Some one forgot to stop (without knowledge) the applicaiton before stopping DB. So this can be excludable case as nothing will happen with this change but there is a chance which causes to your downtime extension.

If your restart of DB does'nt take much time (If it is only restart) till the (some)time application will ping the database to connect.

And normally standard process stops all the appl processes and cleans up the memory occupied by hung processes and cleans up the buffers and greens out swaps - If your stop application as a part of restart.

Regards,

Nick Loy

[Former Member]

I do mostly agree with the statements made so far, but i like to add a few lines. When we were still doing offline backups on some large prod systems we were only shutting the database down, while all application servers remain up. I have to admit that we also had a so called split mirror backup implemented. This means that the backup was done from the mirror disks.

- shutdown the database

- split the mirror disks

- startup the database

- backup from mirror and resync after that

Thus we only had a downtime of 10min and all workprocesses reconnected as soon as the database was up again (parameters rsdb/reco_sleep_time and rsdb/reco_trials). Obviously the backup was taken during non-office hours and all batch jobs where scheduled around the backup window. We don't do regular offline backups on these systems anymore, even the 10min downtime became to much. So technically it is possible to restart only the database, but you shouldn't do it for the reasons given above.

Cheers Michael

[Former Member]

ya only during the Split_offline & offline_force backups..SAP instances can be remain running .....

check this link http://help.sap.com/saphelp_nwpi711/helpdata/en/46/ab9acaba0b62dbe10000000a1553f7/content.htm

Regards,

Shubham

[Former Member]

Thanks Everyone...Now I have a better understanding.

Given the points.

Regards,

Vaibhav

[Former Member]

Hi Vaibhav,

Always shutdown your applicaiton before you shutdown your database:

Shutdown process should be:

1) Shutdown DI (applicaiton servers)

2) Shutdown CI

3) Shutdown database

Regards,

Chris

[Former Member]

Hi Chris,

Thanks for your reply.

I know the sequence but my point here is if someone restarted the DB accidentally then?

Like in my case db restarted without CI and apps. But when I checked the system, everything looks good to me.

Now in this case do I still need to take the restart of complete system following the SAP standard sequence.

Regards,

Vaibhav

[Former Member]

I'd be inclined to restart the whole system ASAP, if only for peace of mind. Is this your production system or just a test/dev system?

[Former Member]

Hi,

As per normal practice, we don't stop Database without stopping SAP application.

Did you really check what was the status of SAP system while DB was down?

In some cases SAP system does not respond properly after this kind of execution.

There will be impact on your SAP background jobs. All jobs should be canceled. Many

processes might get hang.

But if someone did it by mistake, then in my opinion, he would restart the SAP once

fully after DB restart.

Regards,

Sujit.

[Former Member]

Thanks Sujit and Chris,

I think we stop only database during the offline backup. During this time SAP still remains up.

Then what is the difference in my case and during the offline backup?

Regards,

Vaibhav

Edited by: vaibhav421in on Mar 8, 2011 5:16 AM

[Former Member]

Vaibhav,

While taking offline backup, SAP not at all should remain up.

We take offline backup keeping SAP always down.

That is the basic difference between online and offline backup.

During offline backup no change is made in the system as SAP is down

and hence no redo logs are generated. So, if at any point of time we need

to restore the offline backup we do not apply any redo logs;

Even if we take any file system backup, we make SAP service down.

Hope this clarifies.

Regards,

Sujit.

[Former Member]

The worst case scenario is loss of data when bringing the DB offline while the application servers are still online. It is our responsibility to keep systems stable and consistent. Databases are much more forgiving these days and will recover themselves most of the time, but this should not be a risk you are willing to take.

Regarding your question around the backup. Here are some points I can think of:

1) If you bring your application offline before the database you "ensure" that there are no requests being sent to the database before being shutdown.

2) When the database is shutdown it will attempt to do this as quickly as possible, any data that can not be written to the database will be held in the redo log files and applied when the system is starting up. Thus if your application was writing a lot of data it will think this exists in the database, but it does not. Thus it will not be in your backup. A more detailed answer around this should be given by the database forum.

If anyone wants to exend on these points...

Regards,

Chris