Ramchandra's Weblog

Just ……everything about DB2 LUW


December 2008

Db2 performance metrics

DB2 LUW Performance: Progress Review plus Closing Files | Blogs

The Synchronous Read Percentage, or SRP, tells us how much random synchronous I/O DB2 is doing. High SRP values are achieved when high quality indexes are in place. When DB2 does too much prefetch I/O scanning (with asynchronous I/O), SRP will be lower. If you have an OLTP database and SRP is less than 80%, absolutely do not upgrade your hardware – you have physical design problems to fix first.


Java Transaction Service (JTS)

IBM – Learning more about Java Transaction Service (JTS)

Transactional high availability and deployment considerations in WebSphere Application Server V6

IBM WebSphere Developer Technical Journal: Transactional high availability and deployment considerations in WebSphere Application Server V6

The WebSphere Application Server transaction manager stores
information regarding the state of completing transactions in a persistent form
that is used during transaction recovery. This persistent form is referred to
as the transaction recovery log and is used to complete prepared transactions
following a server failure. This activity is referred to as transaction recovery
In addition to completing outstanding transactions, this processing
also ensures that any locks held in the associated resource managers
are released.

Prior to WebSphere Application Server V6, it was necessary to
restart a failed server to perform recovery processing. Version
6.0 introduces the ability for a peer server (another cluster member)
to process the recovery logs of a failed server while the peer
to manage its own transactional workload. This capability is known as peer recovery processing and supports the resolution of
in-doubt transactions without the need to wait for the
failed server to restart. This facility forms part of the overall WebSphere Application Server high availability (HA) strategy.

Cross Node recovery using TSM

dbsupport.cio – Cross Node recovery using TSM (Ramchandra Raikar :

Transaction IDs in DB2 : Retrieve a unique identifier for a unit of work from the DB2 log records

Transaction IDs in DB2

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