In HADR superasync synchronization mode, if the following steps
are executed, standby will hang for ever.
Note: Because standby is hung, any action on standby including
takeover will hang.
1. HADR pair using super aysnc mode is setup with logfilsiz X.
2. HADR primary generates few log's.
3. Standby is deactivated.
4. Run some transactions on primary to move up in number of log
extents.
5. Primary is deactivated.
6. logfilsiz on primary is changed to Y
7. A start hadr on db hadrdb as primary BY FORCE is issued.
8. Few more log's are written with the new logfilsiz
9. Activate the standby.
After step 9, standby will appear hung. You can also confirm
this by looking at the output of db2pd -hadr. If the log extent
number for standby does not move ahead then it could be due to
this hang.
db2diag.log will contain messages similar to the following, note
that the next extent header standby received after extent header
for log 718 is for log 747 instead of 719. Due to this out of
order extent header send issue at the time of logfilsiz causes a
hang on standby.
2012-01-05-04.46.03.978538-300 I391774E443 LEVEL: Info
PID : 18870 TID : 140736989226752PROC :
db2sysc
INSTANCE: db2inst1 NODE : 000
EDUID : 34 EDUNAME: db2hadrs (HDRLNX)
FUNCTION: DB2 UDB, High Availability Disaster Recovery,
hdrHandleXhdrMsg, probe:10175
DATA #1 : <preformatted>
Received HDR_MSG_XHDR, ExtNum 718, firstlsn 00036DEF8000 ExtSize
5000, PageCount 5000, state 0x18211
2012-01-05-04.46.06.062622-300 I392218E448 LEVEL: Info
PID : 18870 TID : 140736989226752PROC :
db2sysc
INSTANCE: db2inst1 NODE : 000
EDUID : 34 EDUNAME: db2hadrs (HDRLNX)
FUNCTION: DB2 UDB, High Availability Disaster Recovery,
hdrHandleXhdrMsg, probe:10175
DATA #1 : <preformatted>
Received HDR_MSG_XHDRCLOSE, ExtNum 718, firstlsn 00036DEF8000
ExtSize 5000, PageCount 5000, state 0x18211
2012-01-05-04.46.06.079451-300 I393037E443 LEVEL: Info
PID : 18870 TID : 140736989226752PROC :
db2sysc
INSTANCE: db2inst1 NODE : 000
EDUID : 34 EDUNAME: db2hadrs (HDRLNX)
FUNCTION: DB2 UDB, High Availability Disaster Recovery,
hdrHandleXhdrMsg, probe:10175
DATA #1 : <preformatted>
Received HDR_MSG_XHDR, ExtNum 747, firstlsn 000391560000 ExtSize
6700, PageCount 6700, state 0x10001 |
