Re: Transparent replication of DB2 data on WAN ?

From: <jl34778_at_mcvax2.d48.lilly.com>
Date: 17 Aug 93 09:00:28 EST
Message-ID: <1993Aug17.090028.1_at_mcvax2.d48.lilly.com>


In article <24o60n$6k9_at_DIALix.oz.au>, manfan_at_DIALix.oz.au (Manuel Tsz Pong Fan) writes:
>
> Our organization is in the process of moving away from an architecture
> which relies solely on DB2/MVS to store and CICS/MVS to access trusted
> corporate data. The option currently favoured by management and heavy
> weight users is to replicate DB2 data onto DOZENS of databases on a WAN.
>
> Before I double my life insurance, can anyone tell me whether any
> vendor provides a solution which will more or less transparently
> synchronize replicas either continuously or at pre-determined intervals?
> Has anyone actually done this?
>
> Can System 10 do it?
>
> Can Oracle handle replication transparently at all?
>
> BTW, is any DBMS vendor besides IBM supporting or planning to support
> DRDA?
>
>
Using SQL*Connect for DB2 and some trickery, you can define an ORACLE7 snapshot directly against a DB2 table. However, the snapshot will always refresh the entire table, because you cannot create a snapshot log on a DB2 table.

SQL*Connect for DB2 is an Oracle product that allows DB2 to participate in a SQL*Net network. So, you also need SQL*Net.

Creating a snapshot on a DB2 table is just like creating a snapshot on a remote ORACLE table, with one exception.

Step 1. Create a database link in the ORACLE database that points to DB2.

	CREATE	DATABASE LINK DB2
		CONNECT TO mvsid IDENTIFIED BY mvspassword
		USING 'T:mvs.tcp.address:sid';

Step 2. Create the snapshot. Snapshots require rowids, but DB2 doesn't have
	them, so join the master table with DUAL so that ORACLE will provide
	rowids.

	CREATE	SNAPSHOT DB2SNAP
		REFRESH START WITH SYSDATE NEXT SYSDATE + 1
		AS SELECT COL1, COL2 FROM DB2TABLE_at_DB2,DUAL

Step 3.	Make sure that your INIT.ORA parameters are set to do automatic
	refresshing of snapshots.

	SNAPSHOT_REFRESH_PROCESSES = 1
	SNAPSHOT_REFRESH_INTERVAL = 360       (wake up every hour)


We are just getting into this stuff. We don't yet have a handle on performance issues. We seem to be able to transfer about 1megabyte/minute from DB2 to ORACLE through our TCP/IP lines. For large amounts of data, it still might be more efficient to export the data from DB2 into a flat file, ship it over to VMS using a high speed transfer, and use SQL*Loader to get the data into ORACLE. We will be doing some comparison testing over the next couple of months. Received on Tue Aug 17 1993 - 16:00:28 CEST

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