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Posssilbe reasons why Db2LUW connections are slow

Technical Blog Post


Abstract

Posssilbe reasons why Db2LUW connections are slow

Body

Following  is a good  document  on  possible reasons  why  db2 connections could  be slow,

/support/pages/node/412221

 

I  just  wanted to highlight  one more area to consider   for the connect slowness.

Sometimes a  database   which  might not be continuously  in use.

Connections are happening  in low numbers and then being terminated  and there is a silent  period  after that before  some more connections are being tried again.

If   the  database  is  not activated  explicitly  what  happens is,   the  first  connection will  activate the database implicitly and then when it will go away the database will be deactivated  implicitly against  the last connection in the database.

As  a result,  when  a  new connection comes after a  delay  it will find the database needed to be  activated  again.

A  database  activation has overheads  depending on the size of the total memory  it need to allocate  during the activation sequence  and other initialization steps there too.


So,  one  easy way to  rule  out  this issue is  to  issue an  explicit  activation  at the beginning  with   "db2 activate  database  <db-name>".   That will keep the database activated continuously   even  if there is no connections  left  in the database.  It will  remain  activated  until  an  explicit  deactivate is issued.

The clue to  find  the symptom  is to  find   FirstConnect  messages  in the db2diag.log  over and over.

Also, there could be  various  reasons why  db2 connections could  be terminated.  It could be as  per the design of the setup or,  by  some abnormal reasons.  Usually  messages with -1224  will show up  in the  db2diag.log file  if connections are being  terminated.

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