Disaster recovery question

[Former Member]

Your forum was recommended for my question/issue

We have two semi-annual disaster recovery tests annually. The pre-test process is composed of restoring the Disaster Recovery Client from the Production client, and allowing one set of users to perform their process procedures on the DRS server, while the other users continue normal business operations on the PRD server.

Earlier this year we upgraded from SAP 4.0b --> 4.7c.

During our first disaster recovery test this year users received a message 'change and transport system not configured' . They were able to continue master data updates, even though they received the message.

We would like to have a real disaster recovery test where we switch from the production system to the disaster recovery system (DRS) and continue our business operations from that server (DRS)(located in another state).

<u><b>What must be done to perform this switchover/switchback process between the two clients once the test is completed</b></u>?

[sivaramakrishn]

Linda,

I understand that you want to do a actual DR simulation and not just a test. And, your main query is to do with how you switchback from the DR site to the original production site after your simulation is all done and signed-off.

This would depend on your database, your replication strategy and the mechanism you use to build & synchronize your DR system. That said, here is a basic list you should consider:

1. Once the Dr site becomes active, make the Production site as the DR and start reverse replication

2. Consider and agree a downtime for the switchover (this way it would be safe and consistent)

3. At the agreed outage, do a final synchronization and shutdown the DR environment.

4. You might also want to copy OS level files (mainly to do with interfaces) to the Production box so that the data integrity is maintained. That holds for logs as well for continuity/troubleshooting

5. Switch on Production & do a validation with a small set of users (others to be locked)

6. Once you are happy, release the system and make sure that the replication is now working from Prod to DR.

Hope that helps

Siva

[Former Member]

Related to 'change and transport system not configured'

Well - you have to change the setup of your transport system after a failover...

This depends on your design in your SAP system, and what you define as part of a DR solution.

Do you include the entire SAP landscape in the DR?

How is your transport landscape setup?

Is it the P system that is transport domain owner?

...

If you only have the PRD system as part of failover, you might need to change your transport routes.

You might have a lanscape like this:

DEV -> TST -> PRD

And you will need a:

PRD -> VIR

Where VIR is a virtual system which enable you to create and release a modification which is transportable (not a local request).

[Former Member]

If I interpreted you correctly: you want to bring up a DR-copy of the PRD system on another server. Then let a limited number of users test this one while all other users continue normal operation on the PRD server.

Be aware that it is pretty dangerous to have both servers running at the same time

You're main concern will be to isolate the DR system from the PRD system and interfacing systems !!!

The result will not be 100% correct:

- it will not be possible to test all interfaces - thus not all business functionality...

the main obstacle with failover systems is interfaces.

- you will not be able to see if the DR system can handle the load

you will not see if the server and/or infrastructure is sufficient

P.S. Remember that the interfacing go both ways.

- You want someone to reach the system - as such you will need to open access into the DR system...

but - you will want "only a limited number of users" to do it.. as such you must play around with SAP logon and/or DNS/IP addresses.

- You do NOT want the DR system to update the PRD system (or send out info to any other partners)

as such - you must restrict outbound traffic from the DR system.

If you do not know what/where to isolate... then rip out the network cable and place the users next to the server

[Former Member]

Hi,

Firstly, Production system data replication in DR system should be proper.

There are number of methods available to do this replication. We can check it by ananlysing the Log SCN number in the both the systems.

As a process of DR implementation better to configure SAPGUI with DR system also, in case live goes down. We can just start DR system and ask end users login through other option.

Hope it helps

Regards

KT

[Syamkriz]

Hi,

1)Make sure your systems are in sync

2)The users must be intimated about the ipaddress changes so that they shall continue working .

3)Before switchover make sure all the users are able to ping to the disaster recovery server ip.

Please let me know if you have further questions

Syam

[Former Member]

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