Downtime for System Migration & Database size/Export dump size

[Former Member]

SAP Expert,

Could you please share your experience for below activities.

Downtime for SAP ECC System/Oracle Migration

Database size/Export Dump size.

Pre-req for migration

Post follow up activities

Thanks in advance

Svasan

[Former Member · Accepted solution]

Hi Experts,

Any others please share your experience for this issue.

Downtime, Database size, System Copy/Migration Tool, Server RAM Size, Processor Speed & Table Splitting or Package Splitting(methods).

We will calculate Downtime for this process and update to Our Customers.

Please help all experts.

Thanks,

Vas

[Former Member · Accepted solution]

Hi Vas,

This field is huge and is very difficult to cover in a discussion.

In the Link http://service.sap.com/osdbmigration you can find a lot of information about the migrations.

Also you have the OS/DB Migration training and certificatio where is reviewed all the the important aspects.

To determine the method to use the first think that you have to verify is the source and target OS and DB. If you changing one of them you usually cannot use the standard DB methods (Backup/Restore) above all if you change the endian.

In case of changing OS and/od DB first bear in mind that to migrate productions environment is mandatory to Order the SAP OS/DB migration check and to have a certified in OS/DB migration that sign the project. Also you should leave some time (3 months) between an upgrade and a migration.

There are several methods standard and advanced. The most common is use the SAP Migration tools (R3Load and JLoad) and whitin there advanced techniques like Package Splitting, Table Splitting, Parallel Export/import, Usorted Export, Incremental Migration. Sometime you have to use your "imagination" to improve the process. Is very important to know how is your current environment, how is the strcture of your database and how will be your future system.

Also you can apply some feature during the migration like apply compression or patitioning for Oracle and Db2.

For some DB managers there are also method out of the SAP Export/import. E.g. Oracle has the O2O - Triple O method in order to migrate DB from Oracle/non-Oracle  to Oracle.

IBM have also software to do the migration of DB2 DB almost online.  Here you have a redbook about DB2 migration for SAP: http://www.redbooks.ibm.com/redbooks/pdfs/sg247774.pdf

There are also additional paid services (Zero DownTime) in case of reduced downtime windows or big databases.

The migration time depends on a lot of factors:

- Hardware capacity in Source and Target systems. As bigger the HW capacity is higher the parallelization and lower the time will be.

- Network Bandwidth.

- DB size. Before Migration consider seriously to reduce your DB space. E.g archive data is a good approach. Bear in mind that after the migration your database will be reorganized so it is a perfect moment.

- DB Structure: Is not the same to have a big database with the most of size concentrate in few tables than a big DB very distributed.

- Data fragmentation.

The only way to estimate the downtime is to test the migration before, and the most of times you need more than one test to find the good way to do it.

Also after the test migration you have to test your functionality.

In summary, this is a huge topic and I'm sure that I have forgot a lo of things.

Hopefully my comments help to you.

Cheers.

Jose

[Former Member · Accepted solution]

Hi Vas,

The DB size will compress to between 10-15% of the current db size. So a 500GB database will create  50-75GB of physical files at the operating system.  You can fix the size of the export files so that each one is, say, 100MB in order to move them across machines more easily.  You can set up the export so that it transfers files on completion to the target system and have the import tool running in parallel pulling files in as they arrive. 

You will need to play with the number of processes that you can run in parallel with exporting, but CPU performance will directly affect the export and import speeds.  One useful option is to table split your top 30-50 tables so that the import is not held back by having to load one or two huge tables sequentially.  You will need to expand your temp tablespace (Oracle) by at least 3 to assist with the export.  A large temp tablespace for the target system will also help the import.  This can be revised in size after the event.

Always use the latest SAP tools for the job.

And, practice, practice, practice!

Hope this helps,

Graham

[Former Member · Accepted solution]

Hi....Jose..

Really Great effort.

Thank You a lot.......

Thank God......

[Former Member · Accepted solution]

Your Welcome Vas,

If some of the comments has solved or has been useful don't forget to mark it as Correct or Helpful answer. It helps to other users to find the correct answers.

Good luck with you migration.

Regards

[Former Member · Accepted solution]

This message was moderated.

[Former Member]

Hi Expert,

Any one update database size and approx. downtime.

Kindly dont divert to Guide.

[sunny_pahuja2]

I can give you lot of example for downtime and database size but it cannot help you. As a matter of fact it depends upon lot of things.

I have done system copy with 12 TB of database with 40 hrs of downtime while I did for 5 TB and it took 20 hrs for export & import. But it does not matter, it depends on how much optimization you do, how much resource your servers have etc.

So, best way to get an estimation is to do test system copy.

Thanks

Sunny

[sunny_pahuja2]

Hello,

Downtime for migration depends upon lot of factors like database size, advance optimization technique that you use lile table splitting/package splitting etc. and CPU/RAM or server.

Export dump size usually 10-20% of total database size.

Prerequisites and post migration steps are described in system copy guide. Please check system copy guide.

Thanks

Sunny

[Former Member]

Hello Sunny,

Thanks for quick reply.

please explain your exp: Database size approximately or exact

Explain: lile table splitting & Package Splitting(where we will get this option in sapinst tool or other tool)

explain some post migration steps as of stored your mind right now.

thnks in advance.

[sunny_pahuja2]

I would recommend you to check system copy guide where you will find all information.

Table splitting and package splitting option you will get in SWPM.

Thanks

Sunny