Thursday, 5 February 2015

SAP HANA Interview Questions- SAP HANA Architecture (Part2)

11. What happens when you set-up a new configuration?
When a new configuration in the SAP LT Replication Server is created, the database connection is automatically created along with a schema GUID and Mass transfer id (MT_ID).
A schema GUID ensures that configurations with the same schema name can be created.
The Mass transfer ID is used in the naming of SLT jobs and the system can uniquely identify a schema.
The mapping of mass transfer IDs and related schema are stored in the SLT control table DMC_MT_HEADER in the SAP LT Replication Server.

12. What are the jobs involved in replication process?
Following jobs are involved in replication process:
1. Master Job (IUUC_MONITOR_<MT_ID>)
2. Master Controlling Job (IUUC_REPLIC_CNTR_<MT_ID>)
3. Data Load Job (DTL_MT_DATA_LOAD_<MT_ID>_<2digits>)
4.Migration Object Definition Job (IUUC_DEF_MIG_OBJ_<2digits>)
5.Access Plan Calculation Job (ACC_PLAN_CALC_<MT_ID>_<2digits>)

13. What is the purpose of master job (IUUC_MONITOR_<MT_ID>)?
Every 5 seconds, the monitoring job checks in the SAP HANA system whether there are new tasks and, if so, triggers the master control jobs. It also deletes the processed entries (tasks) from table RS_ORDER and writes statistics entries into table RS_STATUS (in the relevant schema in the SAP HANA system).

14. What is the purpose of master controller job (IUUC_REPLIC_CNTR_<MT_ID>)?
This job is scheduled on demand and is responsible for:
Creating database triggers and logging table in the source system
Creating synonyms
Writing new entries in admin tables in SLT server when a new table is loaded/replicated

15. What is the purpose of Data Load Job (DTL_MT_DATA_LOAD_<MT_ID>_<2digits>)?
This job should always be active. If the job does not complete successfully, the master controller job restarts it.
This job is responsible for:
• Loading data (load)
• Replicating data (replication)
• Changing status flag for entries in control tables in the SAP LT Replication Server

16. What is the purpose of Migration Object Definition Job (IUUC_DEF_MIG_OBJ_<2digits>)?
This job defines the migration object of a specific table (that you choose to load/replicate), which is the fundamental object for LT replication. The migration object definition should normally be quite fast for all tables.

17. What is the purpose of Access Plan Calculation Job (ACC_PLAN_CALC_<MT_ID>_<2digits>)?
This job calculates the access plan of a specific table (that you choose to load/replicate), and the access plan is used for data load or replication. The access plan is also a fundamental object for the replication. For a normal sized table, access plan calculation should finish quite quickly (less than 1 minute) while large tables might take up to several hours to finish.

18. What is the relation between the number of data transfer jobs in the configuration settings and the available BGD work processes?
Each job occupies 1 BGD work processes in SLT replication server. For each configuration, the parameter Data Transfer Jobs restricts the maximum number of data load job for each mass transfer ID (MT_ID).
A mass transfer ID requires at least 4 background jobs to be available:
One master job
One master controller job
At least one data load job
One additional job either for migration/access plan calculation/to change configuration settings in “Configuration and Monitoring Dashboard”.

19. If you set the parameter “data transfer jobs” to 04 in a configuration “SCHEMA1”, a mass transfer ID 001 is assigned. Then what jobs should be in the system?
1 Master Controller job (IUUC_REPL_CNTR_001_0001)
At most 4 parallel jobs for MT_ID 001 (DTL_MT_DATA_LOAD_001_ 01/~02/~03/~04)

20. What happens after the SLT replication is over?
The SLT replication server creates 1 user, 4 roles, 2 stored procedures and 8 tables.
1 User
1 Privilege
4 Roles
2 Stored procedures
8 Tables
More Questions & Answers :-

1 comment:

  1. very good collection of question answers thank you for sharing. Know more about SAP HANA Training