TALKING WITH DB2 Today’s connectivity options 0 CRISTIAN MOLARO IBM Information Champion Belgium 2009
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TALKING WITH DB2 Today’s connectivity options
0
CRISTIAN MOLARO IBM Information Champion
Belgium 2009
Agenda
CONNECTIVITY BEST PRACTICES POOLING SYSPLEX SUPPORT CONCLUSIONS
CONNECTIVITY
DB2 for z/OS
DB2 requester
DB2 Connect
IBM Data Server Client
IBM Data Server
Runtime Client
IBM Data Server Driver for JDBC and
SQLJ
IBM Data Server Driver
for ODBC and CLI
IBM Data Server Driver
Package
DRDA Connectivity options
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App
App App
≥ 9.5 Fp3
Table of equivalences
This presentation uses V9.7 terminology
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V8 V9 V9.5 & V9.7 DB2 Administration Client DB2 Client IBM Data Server Client DB2 Application Development Client DB2 Runtime Client DB2 Runtime Client IBM Data Server Runtime
Client Java Common Client IBM DB2 Driver for JDBC
and SQLJ IBM Data Server Driver for JDBC and SQLJ
IBM DB2 Driver for ODBC and CLI
IBM Data Server Driver for ODBC and CLI IBM Data Server Driver Package
IBM Data Server Drivers and Clients selection guide
There is a functional overlap Should balance functionality with footprint DB2 Connect Server not required for Sysplex Workload
Balancing (≥ 9.5 Fp3) DB2 Connect license still required
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Smallest footprint
JDBC and SQLJ
ODBC and CLI
OLE DB and .NET
Open source
CLP GUI tools
IBM Data Server Driver for JDBC and SQLJ X X IBM Data Server Driver for ODBC and CLI X X IBM Data Server Driver Package X X X X IBM Data Server Runtime Client X X X X X IBM Data Server Client X X X X X X
Selection guidelines: application view
Set db2.jcc.sqljUncustomizedWarningorException to 1 or 2
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Smallest footprint
Application Performance Sysplex WLB
Seamless failover + ACR (DS)
Type 4 drive X For Java-based dynamic SQL applications
For dynamic SQL only X X
IBM Data Server Driver for JDBC and SQLJ
For Java-based static SQL applications
Supports both static and dynamic SQL
X X
pureQuery using Type 4 driver
Easiest to code. Recommended for new Java based static SQL applications
Supports both static and dynamic SQL X X
Data Server drivers in ODBC/CLI environments
X For C/C++ applications
For dynamic SQL only X X
Data Server drivers in .NET environment X
For C# and VisualBasic applications
For dynamic SQL only X X
Traces available on distributed components
It is a good idea to get used to collect and analyze traces in distributed components
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Client / Driver Available traces
What the trace contains?
IBM Data Server Driver for JDBC and SQLJ (type 4)
JCC Trace It contains both JCC driver trace and DRDA trace. JCC trace contains both JCC driver trace and DRDA trace only when TRACE_ALL is specified
IBM Data Server Driver for ODBC and CLI
CLI trace, db2trc, db2drdat
CLI trace contains the driver trace. db2trc contains db2 client side buffers and DRDA buffers. (db2drdat available from 9.5 FixPack 4)
All other Data Server Clients, DB2 Connect, DB2 ESE and so forth
CLI trace, db2trc, db2drdat
CLI trace + db2trc + db2drdat. db2drdat contains only DRDA buffers.
The choice of the right configuration
Only Java clients were able to exploit Sysplex Workload Balancing functions via direct connections.
This functionality has been extended to all clients.
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ODBC, CLI, .NET, OpenSource
JDBC,SQLJ, pureQuery
DB2 Connect
ODBC, CLI, .NET, OpenSource
JDBC,SQLJ, pureQuery
IBM Data Server Driver for JDBC and SQLJ
DRDA
IBM Data Server Driver package
DRDA
The choice of the right configuration
Most configurations currently using DB2 Connect can use one of the IBM Data Server products:
– Significantly reduced footprint – Simplify infrastructure from 3 tiers to 2 tiers – Reduced network traffic and code path – Simplification of single point of failure management – Simplification of problem determination
But: – More complex software administration for maintenance – A license for DB2 Connect is still required – No gateway functionality – WLB balancing scope reduced to local applications
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Cons Pros
Improved problem determination
Improved availability: elimination of a point
of failure
Improved performance by reduced network traffic and code path
DB2 Connect Server required for XA using multi-transport model
Potential impact to high priority distributed or
mainframe applications
Reduction in control of workload priorities
Replacing DB2 Connect by Clients: Considerations
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Client-side configuration management tools coming soon Most XA-compliant TMs such as WAS use single-transport model
Some DB2 Connect reserved functionalities
Remember: there is no mechanism available to DDF or WLM to classify a workload BEFORE connection: critical and low priority workloads compete for DBATS
DB2 Connect: – Provides gateway, connection concentration and a larger scope
for WLB and Pooling – Simplification of upgrades and maintenance
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DB2 DB2
Connect DB2
DB2 Connect and Hipersockets
Probably the best option for a DB2 Connect server
Get availability advantages of System z at IFL price
Hipersockets support Promotes server
consolidation: reduces Data Center costs
But: WLB and Sysplex Distributor doesn’t consider hipersockets for workload distribution (yet)
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z/OS
DB2
Linux on z
DB2 Connect
Hipersockets
z/OS
DB2
z/OS
DB2
DB2 Private Protocol
DB2 to DB2 PP still supported but officially deprecated in V9 Anyway:
– No changes since V5 (10 years) – Not zIIP eligible: CICS transactions are if TCP/IP + DRDA – Lots of functions only available trough DRDA, like Static SQL,
thread pooling and Stored procedures – Today there is no technical reason to still keep using PP
DBPROTCL zParm removed from V9 – DBPROTOCOL(DRDA) assumed for any BIND/REBIND if not
specified DBPROTOCOL – You may need to change existing BIND/REBIND processes – If specified, DSNT226I and warning RC (4):
OPTION IS NOT RECOMMENDED WHEN BINDING PLANS OR PACKAGES
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DB2 PP would NOT WORK on V?!
Migration shouldn’t require application changes It has an impact on existing BIND/REBIND processes Creation of ALIASES is required Use the PP to DRDA Catalog Analysis Tool DSNTP2DP
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The private to DRDA protocol REXX tool
Creates local and remote BIND commands for PLANS and PACKAGES and build CREATE ALIAS statements
You need to change current BIND/REBIND to include remote Uses catalog information to determine applications having a
remote location dependency: embedded dynamic SQL will usually NOT be indentified
For DB2 V9: highly recommended APAR PK78553 Support for DB2 V7 and V8: APAR PK40433 Shipped with V9, for older versions: http://www.ibm.com/
developerworks/exchange/dw_entryView.jspa?externalID=213&categoryID=32
More information: DB2 for z/OS Installation Guide
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BEST PRACTICES
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Application Programming Best Practices
Limit the size of your result set: – Use the WHERE, GROUP BY, and HAVING clauses – setFetchSize() can be a hint to Java driver for scrollable rowset
cursors
Help the server use limited block fetch (and extra blocks) – Use OPTIMIZE for n ROWS and FETCH FIRST n ROWS – Declare your cursor with FOR FETCH ONLY, or FOR READ
ONLY, and INSENSITIVE STATIC – Use CURRENTDATA(NO) and ISOLATION(CS) when possible
and avoid ISOLATION(RR) – Avoid using WITH HOLD cursor: CLI applications
use with hold cursor by default
Application Programming Best Practices
Use Remote Stored procedures to minimize network traffic. – Native SQL procedures called via DRDA TCP/IP clients are zIIP-
eligible (V9) – Use result set cursors to return data – Use COMMIT on RETURN clause for stored procedures that do
not return result sets
Explicitly close your cursors after you have fetched all data COMMIT often but avoid the use auto-commit Use KEEPDYNAMIC(YES) where necessary to avoid
excessive prepares but remember that it prevents the connection from being inactivated
Application Programming Best Practices
Data Server Drivers use Dynamic Data Format (Progressive Streaming) by default for LOBs and XML data.
Java drivers use multi-row fetch by default for scrollable cursors. CLI driver uses DB2BulkOperations.
Data Server Drivers support both atomic and non-atomic multi-row insert (addBatch (Java), array input chaining (CLI) and DB2BulkCopy (.NET))
Consider using static SQL (pureQuery/SQLJ) to get performance and security benefits over dynamic SQL.
Security information exposed
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SSL and IPSec
SSL (Connection-based using HTTPS protocol) DB2 for z/OS uses the z/OS Communication Server (z/OS
CS) IP Application Transparent Transport Layer service (AT-TLS).
Configuration and setup required at both server and client. To enable for Java connections, use
properties.put("sslConnection", "true”) When using the db2dsdriver.cfg add <parameter
name="SecurityTransportMode" value="SSL"/> IPSec (Host-based) An open architecture for security at the IP networking-layer) No application modifications
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Trusted Context and Roles
A trusted context establishes a trusted relationship between DB2 and another server (could be middleware or another DB2) by evaluating sets of trusted attributes at Connect time.
A role groups together one or more privileges and can be assigned to users. Roles are not available outside of the trusted connection. Reduces the risk of shared app server ids. Provides end-end auditing. CREATE TRUSTED CONTEXT REMOTECTX BASED UPON CONNECTION USING SYSTEM AUTHID WASADM1 ATTRIBUTES (ADDRESS '9.26.113.204’, ADDRESS '$$IPEC1’, SERVAUTH ‘EZB.NETACCESS.ZOSV1R5.TCPIP.IBM’, ENCRYPTION ‘LOW’) WITH USE FOR SAM, JOE WITH AUTHENTICATION ENABLE;
DB2 zParm
CONDBAT: Max. # of distributed connection into DB2 system – includes inactive and active connections, may be large – DB2 queues DBAT requests to become active up to CONDBAT
MAXDBAT: Max # database access threads (DBATs) that can be active concurrently.
– In many installations, max. value determined by available storage in DBM1 (check IFCID 225)
– Set this value conservatively
CMTSTAT INACTIVE: Make a thread inactive after it successfully commits or rolls back and thread does not hold resources
– prerequisite for sysplex workload balancing – inactive connections use less storage and free up DBM1
resources
DB2 zParms
IDTHTOIN: Time in sec an active server thread remain idle before it is canceled
– inactive connections are not subject to idle thread timeout – Strongly recommended to not set to 0 – disable, default works
well
TCPALVER: highly recommended to set to NO (default), applies to TCP/IP only
TCPKPALV: ENABLE or time value in seconds - may need to set a time value since TCP/IP stack default is 2 hours
POOLINAC: time duration that a DBAT remains pooled unless it has received a new unit-of-work request
POOLING
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Pooling
Benefits – Optimization of database attachment resources – Less resources required: Memory, CPU, DBATs , network
Types – DB2 Thread Pooling
• DB2 for z/OS – DB2 Connection Pooling
• DB2 Connect and DB2 UDB for LUW Server products • DB2 Clients and Drivers (limited scope)
– DB2 Connection Concentrator • DB2 Connect and DB2 UDB for LUW Server products • DB2 Clients and Drivers (limited scope)
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DB2 Connection pooling
Allows reuse of an established connection for subsequent connections
Reduction of cost associated with open + close connections
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Applications DDF DBM1
DB2 for z/OS
= Inactive connection
= Pooled DBAT
= Active connection
= Active DBAT
= Pool agent
= Connected agent
= DB2 Client
DDF
DB2 Connect
DB2 Connection pooling
Open connections kept in a pool When application request a disconnection from the host, the
connection to the host is not dropped but given to the pool Reduce CPU utilization in the host Provide little advantage for long running connections (WAS) For short and frequent txn (Web):
– $ connection > $ sql – Reduce CPU and elapsed time per txn
Transparent to applications Security: user identity information is passed along the thread
for user authentication
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DB2 Connection pooling
Implementation: – DB2 connect:
• num_poolagents:def=AUTO; =0 disable • max_coordagents: def=AUTO; SQL1226 if exceeded • DB2CONNECT_IN_APP_PROCESS must be set NO
– JDBC and SQLJ connecion pooling support • Supported by the IBM DB2 Driver for JDBC abd SQLJ • Connection pooling is transparent for the applications • Homogeneus: all connection objects should have the same
properties • Heterogeneus: connection objects with different properties
can share the same connection pool
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Behavior compared
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Using connection pooling
Not using connection pooling
New connect Reuses connection agent Creation of a new connection agent
Commit The connection agent is exclusively retained for the connection
The connection agent is exclusively retained for the connection
Disconnect Release of the connection agent to pool for reuse
Destruction of the connection agent: no reuse
DB2 Connection Concentrator
Allows applications to stay connected without any resource utilization in DB2 for z/OS
Reduces resources required in z/OS increase scalability Data Sharing: provides fail-safe operation and txn level load
balancing
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Applications DDF DBM1
DB2 for z/OS
= Inactive connection
= Pooled DBAT
= Active connection
= Active DBAT
= Connection
= Coordinator agent
= DB2 Client
DDF DBM1
DB2 Connect
DB2 Connection concentrator
Splits agents in 2 entities: – Logical agents application connection – Coordinating agents owns a DB2
connection and thread and executes application requests
Allocates host database resources only for the duration of an SQL transaction while keeping user applications active
The number of DB2 threads and the resources they consume can be much smaller than if every application connection had its own thread
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= Connection
= Coordinator agent
DDF DBM1
DB2 Connect
DB2 Connection concentrator
Implementation: – max_connections > max_coordagents – Not the default
Restrictions – Important restrictions apply: verify before implementing – Application code changes may be necessary – Not for txn WITH HOLD or KEEPDYNAMIC – Must explicitly drop DTT – Only dynamic SQL from CLI – Dynamic prepare requests from embedded SQL not supported – DB2 Connect: cannot use inbound SSL
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Behavior compared
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Using connection concentrator
Not using connection concentrator
New connect Reuses agent Creation of a new connection agent
Commit Release agent to pool for reuse
The connection agent is exclusively retained for the connection
Disconnect No impact on agent Destruction of the connection agent: no reuse
Connection pooling and Connection Concentrator Similar but different objectives Connection pooling
– helps reduce the overhead of database connections and handle connection volume
– an application has to disconnect before another one can reuse a pooled connection
Connection concentrator – helps increase the scalability of DB2 for z/OS by optimizing the
use of your host database servers – a connection may be available to an application as soon as
another application has finished a transaction and does not require that other application to disconnect
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SYSPLEX SUPPORT
Sysplex support
Challenge: a distributed application server needs to find the best available path to the data
Dynamic virtual IP address (DVIPA): – allows servers to be made available independently of hardware
or software failures – allows multiple LPARs to appear to be a single, highly available
network host – applications can be seamlessly moved from one LPAR to
another
Sysplex distributor (SD): – combination of the high availability features of DVIPA and the
workload optimization capabilities of WLM – work distribution based on a dynamically build priority list
DVIPA and Sysplex Distributor – the Concept
DVIPA provides a virtual TCP/IP address into the DS Group Sysplex Distributor routes the connection request to the most
available member based on WLM recommendation
z/OS2 z/OS1
Client
Sysplex Distributor
DB2A DB2B
CF
DVIPA and Sysplex Distributor: better toghether
Benefit: – Connections are successful as long as one member is up – Connection level workload balancing between members – Setup is isolated to z/OS environment
Drawbacks – SD on one lpar may route to a member on a different lpar, which
results into slightly higher response time compared to direct member access
– Information about availability of data sharing members is only considered at creation of a "new" connection but application server typically maintain long-running connections.
DVIPA and Sysplex Distributor: usage
In non Data Sharing DRDA connection environment: – Static VIPA or DVIPA is recommended for network resilience
In Data Sharing DRDA connection environment: – Distributed DVIPA and Sysplex Distributor recommended for
high availability
Is there any additional benefit in using Sysplex WLB at the application server or DB2 Connect if using DVIPA and Sysplex Distributor on z/OS?
– YES! Both DVIPA and Sysplex Sistributor on z/OS and Sysplex WLB on distributed components need to be enabled to ensure highest availability
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The server list
Vital element for Sysplex support At each connection:
– The Sysplex provides a list of weighted priority information for each connection address
– This list is used by DB2 Connect in order to distribute incoming connections:
The server list is exploited by DB2 Connect and DB2 Clients and Drivers for:
– Workload Balancing (WLB): new connection are routed to the Sysplex member with the highest priority
– Fault Tolerance: try connection to other servers in the list in descending priority order; an error is sent only if all connections have failed
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The server list
The server list can be explored with db2pd –sysplex
APAR PK80474 adds display server list to –DIS DDF DETAIL
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Sysplex List: Count: 3
IP Address Port Priority Connections Status 9.12.6.70 38320 53 0 0 9.12.4.202 38320 53 0 0 9.12.6.9 38320 21 0 0
-D9C1 DIS DDF DET DSNL080I -D9C1 DSNLTDDF DISPLAY DDF REPORT FOLLOWS: … DSNL081I STATUS=STARTD DSNL100I LOCATION SERVER LIST: DSNL101I WT IPADDR IPADDR DSNL102I 45 ::9.12.4.105 DSNL102I 42 ::9.12.4.103 DSNL102I 18 ::9.12.4.104 DSNL099I DSNLTDDF DISPLAY DDF REPORT COMPLETE
The server list exploitation
There are no configuration parameters related to enabling Sysplex WLB on DB2 for z/OS server
Used by DB2 Connect and DB2 Clients
zIIP awareness was introduced in APAR PK38867 for DB2 V8 and 9 and z/OS 1R9
There is not Hipersocket awareness available (yet)
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z/OS
DB2
Linux on z
DB2 Connect
Hipersockets
z/OS
DB2
z/OS
DB2
DB2 Connect Sysplex support
Sysplex allows to: – Load balancing: seamless balance connections across
different members of a data sharing group; If connection concentrator is enabled transaction granularity
– Fault tolerance: Try alternate members in case of a member failure: rerouting capability for Sysplex
Enabled by default – but can be disabled if needed – you can also establish Sysplex member affinities
Automatic client reroute for Sysplex (ACR) will retry the connection in case of communication failure. Controlled by:
– DB2_MAX_CLIENT_CONNRETRIES
– DB2_CONNRETRIES_INTERVAL
– DB2TCP_CLIENT_CONTIMEOUT
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Client Sysplex support
Sysplex Workload Balancing (also called transaction-level load balancing) without having to go through DB2 Connect
– New WLB algorithm has built-in Connection Concentrator
Automatic Client Reroute (with seamless failover on transaction boundaries)
– When one member of a Sysplex fails, client automatically attempts to reconnect to another member.
– Application sees no errors (formerly SQL30081N returned)
Direct XA support (for XA TMs using single transport model such as WAS)
– DB2 z/OS APAR PK69659 needs to be applied. – enableDirectXA = true (db2dsdriver.cfg) – Multi-transport models such as BEA Tuxedo not supported
Client Sysplex support
Sysplex support is configured using the db2dsdriver configuration file. Use CA (GUI) with IBM Data Server Client
DB2 Connect migration the command db2dsgcfgfill will create a db2dsdriver.cfg file with most of the required information
WLB is NOT enabled by default: enableWLB is false How db2dsdriver looks like:
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<databases> <database name="DB9C" host="wtsc63.itso.ibm.com" port="38320"> <WLB> <parameter name="enableWLB" value="true"/> <parameter name=”maxTransports value=”100”/> </WLB> <ACR> <parameter name="enableACR" value="true"/> </ACR> </database> </databases>
db2dsdriver.cfg
An XML configuration file that has to be manually edited and used to specify settings for non-Java data server drivers
When CLI settings are specified in multiple places, they are used in the following order:
1. Connection strings parameters 2. db2cli.ini file 3. db2dsriver.cfg file
Tip: Syntax errors are silently ignored in db2dsdriver.cfg. To ensure your settings are used, update your database configuration using diaglevel 4 through CLP or manually update db2cli.ini and check db2diag.log for error messages
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Client Sysplex WLB configuration
Extract of db2dsdriver.cfg
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<databases> <database name="STLEC1" host="9.30.30.5" port="446"> <WLB> <parameter name="enableWLB" value="true"/> <parameter name="maxTransports" value="100"/> <parameter name="maxTransportIdleTime" value="600"/> <parameter name="maxTransportWaitTime" value="30"/> <parameter name="maxRefreshInterval" value="30"/> </WLB> <ACR> <parameter name="enableACR" value="true"/> <parameter name="enableSeamlessACR" value="true"/> </ACR> </database> </databases>
JCC Type 4 Sysplex Workload Balancing
JCC type 4 supports Sysplex Workload Balancing: – JDBC 2.0 datasource since DB2 Connect V8 FP10; JCC 2.7.xx – JDBC 1.2 DriverManager since DB2 Connect 9.5; JCC 3.50.xx
Typical DataSource Properties: – enableSysplexWLB=YES: enables Sysplex WLB. Default is
false disabled – maxTransportObjects: max # of connections to DB2 server
from this DataSource. Default value is -1 meaning no limit
Global properties defined in Global Properties File: – db2.jcc.maxTransportObjects: max # of connections to DB2
server across all datasources. Default value is -1 no limit – db2.jcc.maxTransportObjectIdleTime: time in sec a
connection stays idle before it is closed. Default 60 sec
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CONCLUSIONS
Agenda
CONNECTIVITY BEST PRACTICES POOLING SYSPLEX SUPPORT CONCLUSIONS
New IBM Redbook
Architecture of DB2 distributed systems
Distributed database configurations
Installation and configuration Security Application programming Data Sharing Performance analysis Problem determination
THANKS! Cristian Molaro - [email protected]
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