Connecting 1 SAP source system to multiple HANA via SLT

[Former Member]

Hi experts,

As per SAP documentation http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/a0ead886-8a05-3010-daa7-9ace6bc78... on page 12, one of the possible scenario is connecting 1 SAP source system to multiple HANA systems.

I already have an established configuration in SLT connecting my SAP source system to my HANA box via transacation LTR on the SLT system.

However, when I add new configuration via transaction LTR on the SLT systeam, to connect the same SAP source system to another HANA box, I get an error message: Source system is already used in different Configuration:

How can I create a new configuration in SLT to connect the same SAP source system to another HANA box?

Please assist.

Regards,

Haridev

[Former Member]

Normally we would recommend to delete the old configuration referring to that source system, which was created as 1:1, and start from scratch with 1:N. A switch between 1:1 and 1:N replication is not recommended! It might create some inconsistencies if part of the tables were initially selected for replication in an 1:1 context and later it is switched to 1:N or vice versa. So please only do this if absolutely indispensable! If there is a need to switch between 1:1 and 1:N replication, some more steps are required. In this case, proceed as follows:
1. Add the following authorization to the rfc user in the source system:
  Authorization object S_DEVELOP  (ABAP Workbench)
   Field Activity: Value 42

   Field Devclass: Value $TMP

   Field OBJNAME: /1CADMC/*  and /1LT/*

   Field OBJTYPE: TABL         

   Field P_GROUP:

2. Set, for the corresponding mass transfer, field MULTI_LOGTAB_USE in table IUUC_MT_HEADER and field REUSE_SENDER of table IUUC_REPL_CONFIG to X (if you switch to 1:N) or to space (if you switch to 1:1) in the SLT system. If you switch to 1:N, make sure that in table IUUC_MT_HEADER, for the corresponding mass transfer, field SCENARIO_GUID contains the GUID of the configuration (otherwise, enter this GUID value, which you can get, for example, from table IUUC_REPL_MAP).

3. Stop the replication jobs

4. In transaction iuuc_sync_mon, or ltrc, use expert function "Reset Status of Tables and Synonyms" and activate checkbox "Reset Table/Syn. Receiver" In the same transaction, also execute expert function "Reset Replication Object Definition"

5. Execute report IUUC_REDEFINE_DB_TRIGGERS in the SLT system and specify the corresponding mass transfer ID

6. For tables DD02L, DD02T, and DD08L (and possibly other data dictionary tables chosen for replication), stop and restart the replication. 8. revoke the authorization added before

8. restart the replication jobs

[former_member198535]

Hi Guenther

How are you able to create a configuration with the same name again if we had to delete and re-create?

I.e. in our case we have a lot of views and stored procedures and external access and therefore we are not able to re-create with a new configuration name (and hence SCHEMA name in HANA).

Thanks.

[Former Member]

As soon as you have deleted a configuration, you are free to recreate it with the same name. It is only the three digit mass transfer ID which surely will change, as it is incremented, but this is normally not relevant.
But if you consider deleting a configuration for which you already have many external references as being too disruptive, you can keep and switch the existing configuration, executing the steps I've itemized before.

[former_member198535]

Hi Guenther

Thanks for your update, we just made the changes in our Development by deleting and re-creating, and it worked quite well.

However, is there a document that describes more in technical detail how the multiple usage works?

I noticed that the logging table field IUUC_PROCESSED has change from a CHAR(1) to INT2 and the trigger add the value 0 as default, but I would like to understand how SLT knows when to delete the records in the logging table.

And as a last element, has the multiple usage a negative impact on the replication performance, either having 1 target for a table or 2 targets?

Lastly, is there an impact when running parallel replication using HASH-function on very large source tables?

Thanks a lot for your valuable input.

[Former Member]

We do not have an official external documentation on that. IUUC_PROCESSED will show, in the context of a 1:N replication, which of the consuming configurations already processed that logging table record, as this record may only be deleted once all these configurations have processed it. That's why we use numeric values in this case, with the following meaning:
0 - not yet processed by any configuration
1 - processed by configuration 1 only
2 - processed by configuration 2 only
3 - processed by both the configurations 1 and 2
4 - processed by configuration 3
....
15 - processed by configurations 1, 2, 3, and 4
Neither multiple usage nor parallelization of the replication should have any negative impact on the performance of the replication

[erik_lemen]

There are corrections and steps to follow in SAP Note 1898479 to change an SLT configuration that was originally setup as 1:1 over to 1:N

[former_member494340]

Hello Haridev

Do your two HANA boxes live on the same host? Are you sure the system number for your second HANA system 00?

You can check your SLT version by checking the version of the DMIS component in your SLT system using transaction SPAM.

I am not sure from what build the 1:n scenario became available from.

Thanks

Regards

Fayzal

[Former Member]

Hello Haridev,

Had you checked "Allow multiple usage" when you created the first configuration? If that was not checked, you can't connect same SAP system to multiple HANA boxes.

Also, check SAP notes for the SLT revision you are using. Your scenario is 1:n replication and it was not supported till few months ago,

Hope this helps,

Raja

[Former Member]

Hi Raja,

I have tried checking the Allow Multiple Usage checkbox but it still fails.

How can I check which version of SLT supports 1:n replication and how can I check what version is my SLT running on?

Thanks.

Regards,

Haridev