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SAP LT Replication Server: How to improvethe initial load

Posted by Tobias Koebler Sep 26, 2013Hi, we would like to share a expert guide, that describe the procedure to improve the inital loadvia SLT. Chapters:

1. Introduction2. Access Plan BTC Work Process Requirements3. Which Process Should You Use To Load Large Tables?4. What to know and do before you start5. ECC Source System Preparation6. Netweaver-Based SAP System Landscape Transformation (SLT) Systems7. Load Monitoring8. Process Summary Checklist9. Post Load Considerations

Introduction This Guides describes how large tables can be loaded via SLT into HANA or also toother targets. Here are some examples of challenges our customer have in their landscapes:     •Oracle RAC     • Complex table partitioning models for the larger tables.  For example, partitioning based ona substring of the last character of a column value     • Oracle database statistics that are ‘frozen’ to remove Oracle CBO operations from the dataaccess model. This database architecture was recommended by SAP and has proven to be veryeffective for the customer.Challenges from this architectural approach to SLT included:     • Tableload rates of, in some cases, only 1 million records per day when we would expect 10 millionrecords per hour per work process.     • The source ECC system was also consuming system-crashing volumes of PSAPTEMP.     •  The statistics freeze prevented us from creating indexes for optimized parallel SLT loads.The solution to this issue is a new approach to configuring and executing SLT loads which isbased on accessing data by row ID (Oracle, transparent tables) or primary key (other DB systems,and non-transparent tables for Oracle). This guide can be used for all SAP NW supported databasesystems. Access Plan BTC Work Process Requirements It is important to understand how yourtable load approach may impact the need for system resources so that you can avoid resourcebottlenecks.Each access plan job requires one SAP BTC work process on both the SLT and ECC systems.

Let’s assume that your SLT server has 15 BTC work processes allocated.  You have configured viathe SLT transaction LTR for a Total work process allocation of 10 with 8 of those 10 allocated forInitial Loads.  This leaves 5 available BTC work processes.A table to be loaded has 106,000,000records and you want to use the 5 available BTC work processes for the access plan calculations.  Using the process highlighted in this document, you could divide the access plans into25,000,000 records each and these would run in 5 access plan (ACC*) jobs on SLT – whichcorresponds to 5 access plan (MWB*) jobs on ECC.  Entering 25,000,000 in NUMREC will resultin 5 jobs – 4 jobs processing 25,000,000 records and the 5th job processing 6,000,000 records- assuming that your record count is correct.Let’s now assume that you are using ALL of youravailable BTC work processes on SLT for both SLT (Total/Initial) and access plans.  Good job!  But now, you want to load other tables.  You have available SLT Initial/Total work processcapacity but all BTC work processes are busy and so, for any new table loads, THEIR accessplans, however small, cannot run.  Keep this in mind when allocating your BTC work process

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resources! Which Process Should You Use To Load Large Tables? There are optional methods forloading large cluster and transparent tables.  All perform well but each has its own advantagesand requirements. Cluster Tables:    Type-4 Use the process in this guide to load a large cluster table          • Table will be read by primary key          • Additional SAP batch work processes (BTC) will be needed on the source and SLT serversto handle the multiple access plan jobs.          • Table data will be divided into separate access plans by record count (NUMREC inIUUC_PRECALC_OBJ) of the physical (RFBLG, for           example) cluster table, not the logical(BSEG,for example) cluster table.           • Be careful not to create too many access plans, as all of them need to be processed byyet another batch job in the sender system. As a           maximum, use 8 access plans.          • Requires use of table DMC_INDXCL on source ECC system          • Simple configurationType-4 Manual Delimitation Process           • Table data will be dividedinto separate access plans by specific select criteria (delimitations) for the given table.  You havemore control over the           ranges of data and access plan count.          • Normally not needed, unless you not only want to parallelize the processing but alsowant to restrict the set of data to be processed, for example,           by filtering for a certainorganizational unit, or fiscal year, etc.          • Requires use of table DMC_INDXCL on source ECC system          • More complex configuration steps – contact SAP support Transparent Tables: Type-5Use the process in this guide to load a large transparent table           • Additional SAP batch workprocesses (BTC) will be needed on the source and SLT servers to handle the multiple access planjobs.          • Table data will be divided into separate access plans by record count (NUMREC inIUUC_PRECALC_OBJ).  For each of them, another batch           job will run in the sender system,each of them doing a full table scan of the table.          • Requires use of table DMC_INDXCL on source ECC system          • Simple configuration Type-1 – with index on source system                  • Customermust create a single-field index on source ECC system.  This index is only required for the initialload and may be deleted after the load.          • Does NOT require use of DMC_INDXCL on sourceECC system          • Simple configuration          • Like the standard reading type 3, this typecreates more system load on the sender system, compared to reading types 4 and 5. What toknow and do before you start

• May need to request storage and tablespace from customer• Add security profile S_BTCH_ADMIN to your SLT CPIC user on the source ECC system.

Sometimes, depending on Basis SP, the user will not automatically have the ability to release batchjobs and so your SLT access plan jobs will just sit there waiting to be manually released. Therefore,make sure that you obtain the latest version of role SAP_IUUC_REPL_REMOTE and assign it to theuser assigned to the rfc destination pointing from the SLT system to the source system. You can getthis role from note 1817026.

• Oracle and ASSM issues - Oracle 10.2.0.4 has issues with LOB tables which will impactinserts – they hang – to table DMC_INDXCL.  See note 1166242 for the work around:  alter table SAPR3.DMC_INDXCL modify lob (CLUSTD) (pctversion 10);

ECC Source System Preparation• Minimum DMIS SP: DMIS 2010 SP07 or DMIS 2011 SP02. It is much better to go with the most

recent release of DMIS SP.• For DMIS 2010 SP07 or DMIS 2011 SP02, ensure that note 1745666 is applied via SNOTE

Note: The corrections of this note is included in DMIS 2010 SP08 and DMIS 2011 SP03.

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• For DMIS 2010 SP07 or DMIS 2011 SP02: Ensure that note 1751368 is applied via SNOTE.

Netweaver-Based SAP System Landscape Transformation (SLT) Systems• SLT: Minimum DMIS SP: DMIS 2010 SP07 or DMIS 2011 SP02. • For DMIS 2010 SP07 or DMIS 2011 SP02: Ensure that note 1745666 and 1751368 are applied via

SNOTE.• For DMIS 2010 SP08 or DMIS 2011 SP03: Ensure that all notes listed in Note 1759156 - Installation/

Upgrade SLT - DMIS 2011 SP3 / 2010 SP8 are applied and current.• SLT: Add entry to table IUUC_PRECALC_OBJ

NUMREC:  The number of records to be processed per access plan work process.  Let’s say thatwe have 108,000,000 records and we want to use 5      access plan (ACC*) jobs on SLT – whichcorresponds to 5 access plan (MWB*) jobs on ECC.  Entering 20,000,000 in NUMREC will resultin 6 jobs, 5 of      them handling 20M records each, the last one dealing with the remaining8M records. So you could also specify 22,000,000 as value, in order to have a      more evendistribution among only 5 jobs. Cluster Tables:  NUMREC refers to the record count from thephysical cluster table (RFBLG, for example), not the logical cluster table (BSEG, for      example).NUMREC should be chosen in such a way that, if the delimitation must be done using the primarykey (DB other than Oracle, or cluster or pool table), not      more than around 8 subsets (accessplans) will be created. Keep in mind that in this case, each job will be a full table scan of thecomplete table, which is      not very efficient if done by a large number of jobs. On the otherhand, in case of Oracle ROWID parallelization, you can allow more parallel jobs, because      eachjob will only process its specific ROWID range, rather than doing a real full table scan. This tablealso includes 3 KEYFIELD columns. These can be ignored.

• SLT: Add entry to table IUUC_PERF_OPTION

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parall jobs:  Number of load jobs. This is the maximum number of jobs that might runin parallel for this table, both in the access plan calculation,  and in the load. Sequencenumber:  Controls the priority of the jobs (lower number – higher priority). Usually 20 is a goodvalue. Reading Type:                     • Cluster Table:  Type 4 ->  “ INDX CLUSTER (IMPORTFROM DB)”                    • Transparent Table:  Type 5 -> “INDX CLUSTER with FULL TABLE SCAN”                   NOTE: The labels change between DMIS releases/patches.

• HANA: Select table for REPLICATION in Data Provisioning

• ECC: Review Transaction SM37

               • Job DMC_DL_<TABNAME> should be running (Oracle transparent tables only).  Jobname for all other tables/databases would start                with /1CADMC/CALC_, followed bythe respective table name.               • Once this job is finished, one MWBACPLCALC_Z_<tablename>_<mt id> should be running.               

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                    Starting from DMIS 2011 SP5, the job names will start with /1LT/IUC_CALCSACP andalso include mass transfer ID and table name.

• SLT: Review Transaction SM37• Job ACC_PLAN_CALC_001_01 is running (Starting from DMIS 2011 SP5, the job names will

be /1LT/MWB_CALCCACP_<mass transfer ID> )

               Ideally, more than 1 ACC_PLAN_CALC_001_0 job should be run as soon as the first jobpreparing the precalculation (DMC_DL_<TABNAME>)                has finished.  But only the numberof access plan jobs you specified in the configuration will be started automatically.  Startingmore, up to the                intended parallelization value, has to be done manually.               Assuming that one 1 ACC job is already running, the screen below shows how you would run atotal of 6 jobs concurrently.                In the older Support Packages, we normally provide onlyone job for the access plan calculation step. Starting with DMIS 2011 SP4, or DMIS               2010 SP9, a more flexible control of the calculation jobs is available. You can use transactionMWBMON - Steps Calculate Access Plan to                schedule  more jobs. In the ADRC example,with five parallel jobs, the screen would look as below. However, you need to make sure thatthe value                in field TABLE_MAX_PARALL in table DMC_MT_TABLES is set accordingly, toallow this degree of parallelization, by providing this value in                field parall_jobs whenmaintaining IUUC_PERF_OPTION, as shown above.                You can check which access plans arebeing processed in table DMC_ACS_PLAN_HDR (OWNER guid field of the corresponding recordspoint                to field GUID of DMC_PREC_HDR, the OWNER guid of which in turn points toDMC_MT_TABLES-COBJ_GUID).               

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                         How to use the screen above to manage job count:                          •We have 1 job already running. To set “Number of jobs to be scheduled” to ‘3’ is translated tostarting 3 additional ACC* jobs.                         • If we also select the check box for “Restart”,we are saying that we want a total of ‘3’ jobs to run and so 2 additional ACC* jobs wouldstart.                         • Assuming that we have 8 concurrent jobs and we want to reduce the countto 6: Specify 6 in the “Number of jobs to be scheduled” field,                           select the checkbox for “Restart”. As access plan jobs complete, new jobs will not be started and ultimately, only6 jobs will run concurrently. Load Monitoring

• SLT: Standard MWBMON processes• ECC: SM21/ST22/SM66• ECC: Review Transaction SM37

• Review job log for MWBACPLCALC_Z_<table name>_<mt id> to monitor record count andprogress:

Process Summary Checklist• SLT: Created entry in IUUC_PRECALC_OBJ• SLT: Created entry in IUUC_PERF_OPTION• SLT: SLT batch jobs are running.

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• HANA: Table submitted from HANA Data Provisioning• ECC: Job DMC_DL_<table_name> is running• SLT: ACC* batch job is running• ECC: Job DMC* started/finished and job MWBACPLCALC_Z_<table_name>_<mt_id> started• SLT: All ACC* batch jobs completed• ECC: All MWB* batch jobs completed• SLT: Table loading (MWBMON)• HANA: Table loaded and in replication

Post Load Considerations

After the load has completed, it is good manners to clean up DMC_INDXCL on the ECC system and remove

the table data. Starting with DMIS 2011 SP4, or DMIS 2010 SP9 this is done automatically, with older SPs,

you should to it manually.

On Source System:

Review your data in the DMC cluster table:

     Select * from <schema>.dmc_cluptr order by 1,2,3 where convobj_id=’Z_KONV_001’

SE38->DMC_DELETE_CLUSTER_POINTER

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• • • The conversion object is the same as is listed in DMC_COBJ->IDENT on the SLT server.• Access plan ID is listed in select statement above. Run this command for 00001-00005.• Select 'delete cluster data'

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• There is no output. If it does not fail, then it worked.

This is a techical expert guide provided by development. Please feel free to share your feelings and feedback.

Best,

Tobias 8277 Views Tags: sap_hana, replication, provisioning, slt, sap_lt_replication_server

Kalyan DittakaviNov 8, 2015 8:43 PM

Hi Tobias

Post Tech Ed 2015, we upgraded our SLT systems to SP9 ( DMIS 2011_1_731 and SP09).

One of the main reason for doing this was to get the Filter option in the Initial Load. But surprisingly what i

notice is the Fields for Filters are only the Key Fields of the Table.

In my scenario, I am trying to use MARD Table where we have 600+Million Records and I want to replicate

only from 2014 using the LFGJA ( Fiscal Year of Current Period). But as mentioned above, I am not seeing

LFGJA in filter screen.

Is there any special configuration i need to do to replicate the data based on "Non Key Fields" of a Table.

Mohamed YoussefJul 23, 2015 4:47 PM

on SP8 i am getting precalc is not supported for cluster tables.

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Charlie GilMay 6, 2015 3:37 PM

Hello Tobias

I have a question about improve the initial load.

In the below post, the initial load can be done with 'Performance optimzed' option with additional batch jobs.

How to enable parallel replication before DMIS 2011 SP6

Does it use parallel processing with the 'Performance optimized' option without any other manual steps? If not,

what other manual steps are involved? Same as the old method?

Our DMIS version is DMIS 2011_1_731 SP8 which is the latest.

The following post shows how to configure parallel processing for initial load and it seems it is still valid. Is it

also valid on DMIS 2011 SP8?

http://scn.sap.com/thread/3689563

Thanks

Mahesh ShettyFeb 5, 2015 4:58 PM

Tobias

I have defined Parallel process for the tables and started the replication. The table is very big and taking time to

load. We have still some WPs available and would like to increase the parallel jobs.

1. How do we increase the jobs when the table is in the process of initial load.

2. Do we need to pause the load and then make changes and then resume the load.

Mahesh Shetty

Sachin BhattDec 6, 2014 6:32 PM

Tobias,

I am going to attempt this next week for one of the big transparent table (800GB) in source (DB2).

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I am preparing by taking help from this blog.

Wanted to know more on option reading type 5. You mention above that we may have to create a tablespace if

use this option, can you provide more details on it (which tablespace??)

Kiran NimmagaddaOct 25, 2014 6:38 PM

Good one Tobias ..

Tobias Koebler in response to Tamas Csuka on page 12Sep 5, 2014 11:16 AM

Hi Tamas,

numrec is based on the full table row count.

Best,

Tobias

Tamas CsukaSep 4, 2014 9:18 AM

Hi Tobias,

great blog as alsways.

I would have one question.

If I use DMC_ACSPL_SELECT initial load filter for my cluster table to reduce the data already on ECC, how

should I count the row numbers for the NUMREC field. Should I use the full table row count or only the row

count for the filtered values?

Thanks and regards

Tamas