Summary.
Explanation of a technique used to perform a single host simultaneous migration of an SAP database used effect a Unicode migration.
The author believes using this technique can be used both for Unicode migrations, database type migrations eg Oracle -> DB2 and database reorganizations
Why.
We are in the middle the acceleration of deployment "commodity priced" multisocket, multicore CPU large memory systems often backed by current generation high speed SAN Solutions incorporating SSD drives offering several 100,000 IOP/Sec. With such hardware a 3TB oracle can be backed up in 90 minutes and recovered in 120 minutes, combining for a total of 3.5 hours to move a database . Yet a full Unicode migration on the same hardware using the standard R3load tools with default parameters can take upwards of 40 hours, 10 times slower. Naturally such comparisons are unfair apples vs. orange comparisons, however 3.5 hours vs. 40 hours speaks to the crux of the slowness of using the R3load tools: How to make best use of all available machine resources to deliver timely cutover performance.
Background of R3load Migration Methods.
Standard Method
The classic or basic method is a 2 step approach, First export entire database upon completion then start import.
Importing on the same host, ie database reorg or unicode migration suggest that one must first export to flat files upon completion , build a new database and begin the import. As per the following diagrams
Step 1 : Database export/unload to flat files
Step 2: Database import/load from flat files creates in Step 1.
Note : If migration timeline is not an issue, stop reading here use classic method, the added complexity and time to testing to remove the implicit risk doesn't make sense. Always use this approach unless you cannot do so, the simple way is the best way.
Simultaneous Approaches with SAP Migration Monitor
SAP Migration Monitor is a set of tools that allow for simulatious extraction and load of one database to another. Note 784118
As of NW7 SR1 migration monitor is now built into the standard tool set, so dont worry if you havent heard about it ... its built in.
What does it do: it coordinate loading into a new database whilst the data is being exported from another. Most of the sap documentation around this implies that a new host is required as per the following
Migration Monitor Type A: Database Migration and Conversion Between Hosts Using SAP Migration Monitor
Migration Monitor Type B: Database Migration and Conversion SAME Host Using SAP Migration Monitor
I
During a recent engagement this method was used to great effect perform an Unicode migration export and import a 3.5TB Oracle database in 8.5 hours.
In the following blogs I'll provide a real life example of how this can be done. Whilst the example is for a Unicode migration , it could be used for migration between databases types ( Oracle -> DB2, SQLServer -> MaxDB )
