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Why a tablespace rebalance is not initiating ?

Technical Blog Post


Abstract

Why a tablespace rebalance is not initiating ?

Body

Altered a tablespace  to  add space and  then trying to  rebalance the tablespace with command like,

db2 alter tablespace <tablespace> rebalance

But, the   "db2 list utilities show detail"   or,  "db2pd  -utilities" does not show any  rebalance is running.

The tablespace  shows the status to be,

Tablespace State = 0x'10000000'
Detailed explanation:
DMS rebalancer is active

 

Following two command run successfully,

ALTER TABLESPACE tablespace_name REBALANCE SUSPEND;
ALTER TABLESPACE tablespace_name REBALANCE RESUME;

But, still    rebalance is not restarted.

 

Restart of the database which is supposed to restart any suspended rebalance should restart the same.

That is also not working either.

 

Following query shows the  tablespace is  in FWD_REBAL ACTIVE,

db2 "select varchar(tbsp_name, 30) as tbsp_name,
dbpartitionnum,member,rebalancer_mode,rebalancer_status,
rebalancer_extents_remaining,rebalancer_extents_processed,
rebalancer_start_time from table(mon_get_rebalance_status(NULL,-2))
as t"

 

There is absolutely no messages logged in  db2diag.log

 

So, is this a DB2 bug ?   Or,  what is the reason ?

 

The reason being,   there is an internal   DB2 registry  which was  unknowingly  set by  somebody.

It's  call  REBALANCER

In a  "db2set -all"  output  following could be seen,

[i] REBALANCER=OFF

 

Internal  DB2 registries  are there to be used by DB2 support analysts to help in some critical situations.  And, should not be used casually.

This being internal registry it does not even log  much diagnostics  in the db2diag.log  as  this is supposed to be used consciously by support analysts.

 

To fix the issue  following needs to be done,

db2set  REBALANCER=

db2stop / db2start

That will restart the rebalancers and complete the  tablespace  rebalance.

 

 

 

 

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ibm13286779