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Basic Working of Sybase Replication Server

January 16th, 2010 Leave a comment Go to comments

Hey Guys,

Its my first post of New Year 2010. I am trying to put the basic understanding of Replication Server and whys it needs more monitoring. Hoping you will enjoy it!

Wishing you great new year 2010 ahead !

Basic Working of Replication Server

PDS : Primary Data Server
PDB : Primary Data Base

RDS : Replicated Data Server
RDB : Replicated Data Base

PRS : Primary Replication Server
RRS : Replicated Replication Server

RSSD : Replication System Database

1. RepAgent reads the record from transation log of the PDB for the tables which are marked for replication.

2. Logs into the PRS and write transactions in inbound queue of PDB in stable device.

3. Holds Data in inbound queue , untill it recieves commit.

4. Uses subscription information in its RSSD to decide what to do with the each transaction, after the commit:

i Discards the rans if there is no subscription.
ii Writes the transaction to the out bound queue if there are subscription.

5. Writes commited trans only in outbound queue according to subscription.

6. Sends transactions to their destination, it depends upone two things

i) if Replicated Database is managed by PRS
Apply changes to RDB using the DSI thread our the connection.

ii) If their are two server, RRS is managing RDB
Send commited trans to RRS over route.
RRS apply that changes in RDB

7. If apropriate, uses function string information in RSSD to compose command to submit to replicate database.

Source : sybooks and www.

As you people are seeing, there are lot of movement of trans/record , and for these trans movements Replication Server uses lot of threads(DSI,RSI,SQT,SQM etc).

If any one of thread stops , replication ceases , even it can hamper PDB performance.

Thats why it is little bit difficult to manage, not difficult, we can say, its need better monitoring.

If I am missing any thing , please add in comments.

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