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08-02-10, 03:40
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Registered User
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Join Date: Jan 2010
Posts: 152
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Best way of testing HADR
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Hello Folks,
I finally created my HADR and its running ( as the Control Center says )
But:
What is the best way of seeing whether the clients connect to the standby database.
The problem is that when i enter a " db2 list active databases " after a takeover
the database shows no clients connected ...
when i do the takover back there are the clients connected again.
Thanks in advance!
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08-02-10, 15:51
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Registered User
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Join Date: May 2003
Location: USA
Posts: 5,198
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If you do a takeover and the applications are not connected to the new primary, you have a problem. To verify that you have actually completed the failover successfully, run this command:
db2pd -d <db-name> -hadr
If you don't see connections after a successful takeover, either the applications are not using Automatic Client Reroute, or you are not using a VIP (virtual IP that your system admin person moves with the HADR primary during a takeover via some script).
__________________
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390
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08-03-10, 02:29
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Registered User
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Join Date: Jan 2010
Posts: 152
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Hello Marcus,
Thank you for the reply.
I think its a problem of the applications because both servers dont use virtual IP Adresses. But how can i find out whether the applications use Automatic Client Rerouting or not?
Thanks in advance 
DB_N00b
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08-03-10, 14:52
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Registered User
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Join Date: May 2003
Location: USA
Posts: 5,198
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First, you have set up the Automatic Client Reroute configuration in the server db cfg.
If your client uses the type 2 DB2 client, then it will automatically use the reroute the ip address/hostname; however, your application may need to have retry logic if it gets an HADR takeover SQL error code (if it is working properly it will pick up where it left off after a retry of the last statement). The auto reroute info is stored on the client db catalog (db2 list db directory--run this on the client) that it gets from the server upon first connection.
If your application uses the DB2 universal driver (type 4) then it is a little more complicated because the application has to persist the automatic re-reroute information on its own that it gets from the server, and must also have retry logic after a takeover.
__________________
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390
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08-04-10, 01:44
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Registered User
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Join Date: Jan 2010
Posts: 152
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Hmm you mean to enter the command:
"db2 update alternate server for database sample using hostname <Primary machine IP address> port <instance port>"
I did that for each database but its not working ...
any more ideas?
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08-04-10, 02:19
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Registered User
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Join Date: May 2003
Location: USA
Posts: 5,198
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Quote:
Originally Posted by DB_N00b
Hmm you mean to enter the command:
"db2 update alternate server for database sample using hostname <Primary machine IP address> port <instance port>"
I did that for each database but its not working ...
any more ideas? |
If you want help, you will have to supply more details about exactly what you did to configure HADR and automatic client reroute, and what extactly you did to test it. Words are not sufficient, exact commands, db cfg output, and client commands are required.
__________________
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390
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08-04-10, 03:41
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Registered User
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Join Date: Jan 2010
Posts: 152
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Code:
HADR database role = PRIMARY PRIMARY
HADR local host name (HADR_LOCAL_HOST) = 6.213.48.223 6.213.48.223
HADR local service name (HADR_LOCAL_SVC) = hadr_fdbkdb hadr_fdbkdb
HADR remote host name (HADR_REMOTE_HOST) = 6.213.48.221 6.213.48.221
HADR remote service name (HADR_REMOTE_SVC) = hadr_fdbkdb_int hadr_fdbkdb_int
HADR instance name of remote server (HADR_REMOTE_INST) = db2inst1 db2inst1
HADR timeout value (HADR_TIMEOUT) = 120 120
HADR log write synchronization mode (HADR_SYNCMODE) = NEARSYNC NEARSYNC
HADR peer window duration (seconds) (HADR_PEER_WINDOW) = 0 0
First log archive method (LOGARCHMETH1) = LOGRETAIN TSM:MCDWH08
Options for logarchmeth1 (LOGARCHOPT1) =
Second log archive method (LOGARCHMETH2) = OFF OFF
Options for logarchmeth2 (LOGARCHOPT2) =
Failover log archive path (FAILARCHPATH) =
Number of log archive retries on error (NUMARCHRETRY) = 5 5
Log archive retry Delay (secs) (ARCHRETRYDELAY) = 20 20
Vendor options (VENDOROPT) =
Auto restart enabled (AUTORESTART) = ON ON
Index re-creation time and redo index build (INDEXREC) = SYSTEM SYSTEM (RESTART)
Log pages during index build (LOGINDEXBUILD) = ON ON
Default number of loadrec sessions (DFT_LOADREC_SES) = 1 1
Number of database backups to retain (NUM_DB_BACKUPS) = 20 20
Recovery history retention (days) (REC_HIS_RETENTN) = 20 20
Auto deletion of recovery objects (AUTO_DEL_REC_OBJ) = ON ON
TSM management class (TSM_MGMTCLASS) = MCDWH08
TSM node name (TSM_NODENAME) =
TSM owner (TSM_OWNER) =
TSM password (TSM_PASSWORD) =
Automatic maintenance (AUTO_MAINT) = OFF OFF
Automatic database backup (AUTO_DB_BACKUP) = OFF OFF
Automatic table maintenance (AUTO_TBL_MAINT) = ON ON
Automatic runstats (AUTO_RUNSTATS) = ON ON
Automatic statement statistics (AUTO_STMT_STATS) = OFF OFF
Automatic statistics profiling (AUTO_STATS_PROF) = OFF OFF
Automatic profile updates (AUTO_PROF_UPD) = OFF OFF
Automatic reorganization (AUTO_REORG) = OFF OFF
Enable XML Character operations (ENABLE_XMLCHAR) = YES YES
WLM Collection Interval (minutes) (WLM_COLLECT_INT) = 0
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08-04-10, 03:49
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Registered User
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Join Date: Jan 2010
Posts: 152
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For the ACR i entered the command
Code:
db2 update alternate server for database fdbkdb using hostname 6.213.48.223 port 50000
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08-04-10, 04:21
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Registered User
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Join Date: Jan 2010
Posts: 152
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When I enter the command
db2 list active databases, i get this:
Code:
Active Databases
Database name = FDBKDB
Applications connected currently = 0
Database path = /daten/db2inst1/NODE0000/SQL00003/
Database name = JCRDB
Applications connected currently = 6
Database path = /daten/db2inst1/NODE0000/SQL00002/
Database name = LMDB
Applications connected currently = 10
Database path = /daten/db2inst1/NODE0000/SQL00004/
Database name = WPSDB
Applications connected currently = 18
Database path = /daten/db2inst1/NODE0000/SQL00001/
When I do the hadr takeover, the role switch is working from primary to standby, but no clients are connected anymore ... 
what can i do therefore?
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08-04-10, 08:13
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:-)
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Join Date: Jun 2003
Location: Toronto, Canada
Posts: 4,449
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Quote:
Originally Posted by DB_N00b
When I do the hadr takeover, the role switch is working from primary to standby, but no clients are connected anymore ... |
The DB2 client does not know that the connection to primary is broken until it attempts to use it. It is only at that time, I think, that it will try to re-establish the connection.
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08-04-10, 08:15
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Registered User
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Join Date: Jan 2010
Posts: 152
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Uh right - I havent thought of that.
Thats because of the HADR Timeout, right?
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08-04-10, 08:37
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Registered User
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Join Date: May 2003
Location: USA
Posts: 5,198
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Test it out with your own own Command Line Interface connection to the database from a remote client. It only works automatically when you have a type 2 client, a type 4 client is more complicated and requires some changes to the application to persist the alternate server.
__________________
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390
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08-04-10, 08:45
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Registered User
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Join Date: Jan 2010
Posts: 152
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works now thank you guys! 
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Best way of testing HADR
