Must know Database facts for WAS 6.1

Transcription

1 IBM Software Group Business Unit or Product Name Must know Database facts for WAS 6.1 High Availability and more Soloman Barghouthi WebSphere Support Technical Exchange 2007 IBM Corporation

2 Disclaimer THE INFORMATION CONTAINED IN THIS DOCUMENTATION IS PROVIDED FOR INFORMATIONAL PURPOSES ONLY. WHILE EFFORTS WERE MADE TO VERIFY THE COMPLETENESS AND ACCURACY OF THE INFORMATION CONTAINED IN THIS DOCUMENTATION, IT IS PROVIDED AS IS WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED. IN ADDITION, THIS INFORMATION IS BASED ON IBM S CURRENT PRODUCT PLANS AND STRATEGY, WHICH ARE SUBJECT TO CHANGE BY IBM WITHOUT NOTICE. IBM SHALL NOT BE RESPONSIBLE FOR ANY DAMAGES ARISING OUT OF THE USE OF, OR OTHERWISE RELATED TO, THIS DOCUMENTATION OR ANY OTHER DOCUMENTATION. NOTHING CONTAINED IN THIS DOCUMENTATION IS INTENDED TO, NOR SHALL HAVE THE EFFECT OF, CREATING ANY WARRANTIES OR REPRESENTATIONS FROM IBM (OR ITS SUPPLIERS OR LICENSORS), OR ALTERING THE TERMS AND CONDITIONS OF THE APPLICABLE LICENSE AGREEMENT GOVERNING THE USE OF IBM SOFTWARE 2007 IBM Corporation 2

3 Agenda Business Unit or Product Name Overview DB2 and WAS V6.1 Oracle and WAS V6.1 Q&A 2007 IBM Corporation 3

4 Overview WebSphere Application Server V6.1 (WAS V6.1) supports the following databases: DB2, Oracle, Sybase, Informix, SQLServer, Derby WAS takes the pain from having the applications be backend database dependent. Instead, WAS handles and hides away the differences in backend database through the Relational Resource Adapter (RRA) IBM Corporation 4

5 Agenda Overview DB2 and WAS V6.1 Oracle and WAS V6.1 Q&A 2007 IBM Corporation 5

6 Advanced DB2 features in WebSphere AppServer V6.1 DB2 Automatic Client Reroute DB2 Trusted Context 2007 IBM Corporation 6

7 DB2 Automatic Client Reroute (ACR) Enables DB2 UDB client applications to recover from a loss of communication so that application can continue to work with minimal or no interruptions. ACR can be used in the following DB2 environments: Enterprise Server Edition (ESE) with the data partitioning feature (DPF) Data Propagator (DPROPR)-style replication High availability cluster multiprocessor (HACMP) High availability disaster recovery (HADR). Clients automatically redirected to the standby database upon failure Alternate server information is passed to the client on the first successful connection to the database. Alternate server information is used for all subsequent connections to the database if the primary DB is down IBM Corporation 7

8 DB2 Automatic Client Reroute (ACR) DB2 Automatic Client Reroute (ACR) is enabled with both DB2 JDBC Universal Drivers Type2 and Type4. There are some subtle differences in behavior between the DB2 JDBC Universal Drivers Type2 and Type4 versions IBM Corporation 8

9 DB2 Automatic Client Reroute (ACR) DB2 Universal Driver Type 2 DB2 Universal Driver Type 4 DB2 server will update the JDBC Driver (i.e. client) with the alternate server information. The entire process is transparent to the user. On the JDBC Driver side, alternate server information stored in memory (i.e. JVM ) and in DB2 Database Directory (persistent on disk). DB2 server will update the JDBC Driver (i.e. client) with the alternate server information. The entire process is also transparent to the user. On the JDBC Driver side, the alternate server information stored in memory (i.e. JVM) only IBM Corporation 9

10 DB2 Automatic Client Reroute (ACR) Who Cares!!!! 2007 IBM Corporation 10

11 Scenario 1 Type 4 WebSphere Application Server JVM Alternate Server= host2 Port = Automatic Client Reroute Client application automatically resumes on Standby tx tx Network Connection tx tx tx HADR Keeps the two servers in sync host1 host2 Primary Server Standby Server 2007 IBM Corporation 11

12 DB2 Automatic Client Reroute (ACR) 2007 IBM Corporation 12

13 DB2 Automatic Client Reroute (ACR) 2007 IBM Corporation 13

14 DB2 Automatic Client Reroute (ACR) 2007 IBM Corporation 14

15 Scenario 2 Type4 with binding WebSphere Application Server JVM Alternate Server= host2 Port = Automatic Client Reroute Client application automatically resumes on Standby tx tx Network Connection tx tx tx tx HADR Keeps the two servers in sync host1 host2 Primary Server Standby Server 2007 IBM Corporation 15

16 DB2 Automatic Client Reroute (ACR) Other things to know when dealing with DB2 ACR: DB2 Universal driver throws an SQLException with error Code of when client reroute happens when connection is being used. The and the reroute happens on each connection. WAS maps the SQLException to Stale Connection Exception in order to purge the connection pool (assuming purge policy is Entire Pool) WAS Applications would then deal with the Stale Connection Exception as they typically do (i.e. get a new connection and retry logic) IBM Corporation 16

17 DB2 Automatic Client Reroute Best practices WebSphere Connection Pool Purge policy should be set to Entire Pool in order to avoid returning un-routed connections to the application. If HADR takeover is planned, WAS admin should purge the connection pool just before doing an HADR takeover to minimize the number of failed transactions by minimizing the number of bad connections IBM Corporation 17

18 DB2 Trusted Context 2007 IBM Corporation 18

19 DB2 Trusted Context A trusted context is an object the database administrator defines that contains a system authorization ID and a set of trust attributes. The relationship between a database connection and a trusted context is established when the connection to the database server is first created, and that relationship remains for the life of the database connection. This feature will allow WAS to use the trusted DB2 Connection under a different user without reauthenticating the new user at the database server (assuming the Trusted Context is created without authentication option being required) IBM Corporation 19

20 DB2 Trusted Context DB2 Trusted Contexts offers the following benefits: Accountability Strengthen database security Ease of use 2007 IBM Corporation 20

21 DB2 Trusted Context DB2 Trusted Context is introduced in WebSphere Application Server V and can be used with any DB2 version that has the TrustedContext support (for now DB2 on Z V9.1) Enabling DB2 Trusted Context support In WebSphere Application Server V6.1 is as simple as running a script 2007 IBM Corporation 21

22 Agenda Overview DB2 and WAS V6.1 Oracle and WAS V6.1 Q&A 2007 IBM Corporation 22

23 Oracle Real Application Clusters (RAC) Myth: IBM WebSphere Application Server doesn t work with Oracle RAC. Fact: IBM WAS does work with Oracle RAC IBM WAS supports RAC but doesn t certify with it. RAC10g can work with any release of WAS RAC9i requires , or (PQ99118), due to an Oracle9i RAC problem IBM Corporation 23

24 Oracle Real Application Clusters (RAC) continue Oracle9i RAC problem: When starting an Oracle node, Oracle jdbc driver will return a connection from the starting Oracle node before its completely up and running which will result in an exception thrown if the connection is used. Workaround added in WebSphere under (PQ99118). Details of the workaround and how to enable it is found in: IBM Corporation 24

25 RAC & XA Oracle RAC & XA Limitation. When Oracle Node failover happens, the alternate Oracle node will open for business before recovery is complete between oracle nodes. The above will result in one of the following: ORA-24756: transaction does not exit when attempting to commit/rollback ORA lock held by in-doubt distributed transaction 2007 IBM Corporation 25

26 RAC & XA workaround in WebSphere Define a singleton Oracle Service and make sure loadbalancing is off on it Configure each WAS cluster member to point to a singleton Oracle Service. The above will cause the loadbalancing to move up to WAS. Since WAS clusters have transaction affinity, we are guaranteed to never span a global transaction over multiple Oracle nodes. Note that the XA limitation is lifted in Oracle 11g IBM Corporation 26

27 RAC & XA workaround in WebSphere x IBM Http Server x Connection pool WAS cluster member 1 WAS cluster member 2 Connection pool jdbcdriver x Jdbc xdriver x P S S P x node1 u Oracle Node 1 Inter connect Node2 U x R Shared Disk R 2007 IBM Corporation 27

28 RAC & XA problem IBM Http Server x x WAS cluster member 1 Jdbc driver x x WAS cluster member 2 x Jdbc Driver x P P P P x node1 u Inter connect U Oracle Node 2 Node2 x Shared Disk R R R 2007 IBM Corporation 28

29 Bad connections in the WAS pool & rebalancing of connections across the RAC nodes. WAS handles clearing its connection pool from all bad connections upon receiving an exception indicating that the Oracle node is down. For rebalancing of the WAS connection pool to all the Oracle RAC nodes when new nodes are added to the Oracle RAC environment, or when a down Oracle comes up, the following options are available: Purging the WebSphere connection pool using MBeans (thus, forcing the pool to be repopulated with new connections from all Oracle nodes. For more details, see Configuring WebSphere connection pool Age Timeout IBM Corporation 29

30 Oracle Implicit Connection pooling Oracle 10g JDBC driver connection pooling requires the use of the OracleDataSource. Attempt to use the OracleConnectionPoolDataSource results in: java.sql.sqlexception: Connection Caching Not Enabled or Not a Valid Cache Enabled DataSource Oracle 10g connection pooling is not supported in XA drivers. Attempt to use the OracleXADataSource will result in: java.sql.sqlexception: Can not use getxaconnection() when connection caching is enabled Through Oracle Notification Service (ONS), Oracle does support UP event load-balancing of connections and the cleanup of connections on the DOWN event IBM Corporation 30

31 WebSphere AppServer V6.1 & Oracle Connection pooling WAS ifix is needed to enable Oracle Connection pooling Steps to enable Oracle pooling in WAS: User-defined datasource and use Implementation class: oracle.jdbc.pool.oracledatasource helper: com.ibm.websphere.rsadapter.oracle10gdatastorehelper custom properties: connectioncachingenabled = true disablewasconnectionpooling = true removeexistingoracleconnectionpoolifexists = true URL=<URL> 2007 IBM Corporation 31

32 Oracle Story in WebSphere AppServer V6.1 Oracle Real Application Clusters (RAC) RAC best practices: WAS connection pool should be purged after new Oracle nodes or added or down Oracle nodes are brought up. When using XA, you should configure Oracle Singleton services. Service should be defined with DTP (if Oracle 10gR2). Configure WAS connection pool with Failing connection only. This will avoid purging good connections unnecessarily when one of the Oracle nodes go down. Optimization was added to WAS connection pool so that a pretest is automatically done on all connections in the pool after a bad Stale Connection Exception detected. As of IBM Corporation 32

33 Oracle Story in WebSphere AppServer V6.1 References: WAS RAC support statement Oracle 9i RAC limitation IBM Corporation 33

34 Agenda Overview DB2 and WAS V6.1 Oracle and WAS V6.1 Q&A 2007 IBM Corporation 34