How to choose Heterogeneous or homogenous System Copy?

[Former Member]

Dear All:

I want to update the hardware of sap system which os is linux.so,maybe need to do a system copy.My plan is the new target system will be installed at IBM AIX(unix),but my prd system is very important for our business and downtime must less than 10 hours.The new target system will replace the sourse system as a production system.

I think maybe i should choose homogenous System Copy which is the best choice for this project.Is it right?

Can you tell me the advantage and disadvantage between Heterogeneous and homogenous?Thanks!

Brian yuan

[Former Member · Accepted solution]

Brian,

Agree with Markus - this is hetergenious in nature. You did not mention if you are changing your DB platform as well.

An idea for you, and something I've done, is to build the 'new' production system on your new hardware as a blank SAP system. Then, if you are say running Oracle, you can restore a database backup to the new system, and use redo logs to keep the system up to date. You can run the systems in parallel. When you are ready to do the cutover, you take the last redo log from Oracle, apply it to the new system and finish the recovery. In our case, the cutover took about 2 hours in total.

Additionally, if something goes wrong with the cutover, you can just go back to the original system.

It takes some setup and planning, but it's much less painless than trying to jam everything into a 10 hour window - You will most likely NOT be able to export the current SAP system, install the new SAP system and perform standard post install tasks in this time unless you have a very small database and very fast hardware.

Hope this helps.

Tim

[markus_doehr2 · Accepted solution]

An idea for you, and something I've done, is to build

the 'new' production system on your new hardware as a

blank SAP system. Then, if you are say running

Oracle, you can restore a database backup to the new

system, and use redo logs to keep the system up to

date. You can run the systems in parallel.

This won´t work - because of different endianess. You can´t "use" redo logs produced on a Linux box to read them back into an AIX box...

When you

are ready to do the cutover, you take the last redo

log from Oracle, apply it to the new system and

finish the recovery. In our case, the cutover took

about 2 hours in total.

This works if you change the hardware on the same endianess (BIG > BIG, LITTLE>LITTLE)

It takes some setup and planning, but it's much less

painless than trying to jam everything into a 10 hour

window - You will most likely NOT be able to export

the current SAP system, install the new SAP system

and perform standard post install tasks in this time

unless you have a very small database and very fast

hardware.

One COULD possibly manage that with transportable tablespaces (see Note 1035051 - Transportable tablespaces) but I´m not sure, if this is support by SAP. The correct way would be to use R3load to export and import the database.

Admittedly - if he goes for Linux on PPC things look different...

--

Markus

[Former Member · Accepted solution]

Hi Tim:

I should confirm the target system will be the same as source system like backgroud job,batch input,customizing configurations and so on .These should be transferred to target system.So,I think install a new sap system and recovery database maybe can't suitable for the requirements of this project!Can you give me another method to solve it?

Thanks for youe help!

Brian yuan

[Former Member · Accepted solution]

Hi Markus:

I mean the homogeneous copy is I won't change the target os and db.I am not sure homogeneous copy wether will be better than heterogeneous copy and suitable for my requirements.Could you tell me the advantage and disadvantage for chosing homogeneous and heterogeneous(Linux --Linux or Linux -- AIX )?Thanks a lot!

Brian yuan

[markus_doehr2 · Accepted solution]

Now I´m completely confused.

Usually the platform is the first choice, not the method of copying

You have a production system running on some platform. If you copy to the same platform/db it´s a homogeneous copy, if not, then it´s a heterogeneous copy. If you go for the latter (heterogeneous) and the system is a production system, you need to get SAP involved (or at least a certified migration consultant).

If you production is on AIX and you choose to go for Linux you need to go that way, if it´s AIX you can just "copy" it over using backup/restore or any other copy method that´s officially supported (see the system copy guide).

Again: you can´t take your Oracle database from your AIX box and "copy" it to the LInux box, the copy itself will work but you won´t be able to run that database. In that case you need to completely export via R3load and import again.

--

Markus

[Former Member · Accepted solution]

Hi Markus:

Thanks for your reply!

My sourse server is linux,db is oracle.The first, my plan is the system of target server installed Unix,db is oracle.But i found maybe it is difficult to do the system copy by myself.So, I want to install linux which version is same as the sourse system at target system.This method maybe will be easier than Heterogeneous copy.Is it Okey?

Looking forward to wait your reply!Thanks!

Brian yuan

[markus_doehr2 · Accepted solution]

YEs - that is ok

--

Markus

[Former Member · Accepted solution]

Markus,

when running on Oracle10 it introduces a possibility to use backup/restore in an heterogenious environment including big endian/little endian conversation.

the technical basis for that is transportable tablespaces.

The procedure is nothing for SAP novices.

Peter

[markus_doehr2 · Accepted solution]

Hi Peter,

I suggested that already (see above) - but that doesn´t include applying redo logs from a different platform.

--

Markus

[markus_doehr2]

You can´t "choose" between those two - which one you need is dependent on source and target system

Homogeneous means: "same OS - same DB"

Heterogeneous means: "different OS - same DB / different DB - same OS / both change"

What you will do is a "heterogeneous" migration. For this migration you need a certified Basis consultant from SAP on-site, otherwise you will loose support for the target system (check http://service.sap.com/osdbmigration), you can´t do this on your own.

Additionally take into consideration that you change your endianess (if it´s Linux on X86), so if you have binary data exchanged between this system and other systems, the other system must be made aware of that.

Also take into account, that your printer definitions will change (AIX is different than Linux in that area) and that all those need to be recreated on OS level (if you use OS level printing).

--

Markus