changing the value of VDWQT in DB2 for Zos

JITINDER CHOUDHARY

changing the value of VDWQT in DB2 for Zos

Hi All,

 

We are planning to change the value for VDWQT in db2 for z/OS. Could you please let us know how to do this and also please let us know if any downtime is required for this or not.

 

Thanks in Advance !!!!

Joel Goldstein

changing the value of VDWQT in DB2 for Zos
(in response to JITINDER CHOUDHARY)
By command.



You should understand why you want to change it, and it effects of the value you plan to use.





Joel Goldstein
Responsive Systems
Buffer Pool Tool(R) for DB2, the worldwide industry standard

Predicts the IO rate/Sec for tuning changes
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From: JITINDER CHOUDHARY [mailto:[login to unmask email]
Sent: Friday, February 02, 2018 6:59 AM
To: [login to unmask email]
Subject: [DB2-L] - changing the value of VDWQT in DB2 for Zos



Hi All,



We are planning to change the value for VDWQT in db2 for z/OS. Could you please let us know how to do this and also please let us know if any downtime is required for this or not.



Thanks in Advance !!!!



-----End Original Message-----

Javier Estrada Benavides

RE: changing the value of VDWQT in DB2 for Zos
(in response to Joel Goldstein)

Hey Jitinder, how's it going?

   If I remember correctly, you're using the CA suite for Db2, so it's easier to do it that way. Go to TT (Thread Terminator) and look for the buffer pools options, from there you can change the thresholds for any Bpool on your Db2.

  As Joel mentioned, you should also check the effects of changing that threshold as many things could happen afterwards. In the worst case scenario, you would have a specific TS monopolizing your Bpool (depending on the new value and also from DWTH) so you might want to isolate that one TS (or perhaps you already did and that's why you're increasing VDWQT). We could help more with a few more details from your side.

Hope that helps :)

Regards,

Javier Estrada Benavides, Mexico

IBM Champion

IBM Certified System Administrator - DB2 11 for z/OS

IBM Certified Database Administrator - DB2 11 DBA for z/OS

JITINDER CHOUDHARY

RE: changing the value of VDWQT in DB2 for Zos
(in response to Javier Estrada Benavides)

Hi Javier,

Could you please let me know what details you required from our end to help more.

Also if we are doing change from CA tool, after IPL changes will not reflect. It will show the same value that was early. AS we had done for DSMAX last week but changes are not reflecting after IPL so we had changed again. If we are doing from CA tool then i think changes are not permanent when ever there is IPL we need to change the value.

Could you please suggest more on this.

Thanks in Advance!!!!

Javier Estrada Benavides

RE: changing the value of VDWQT in DB2 for Zos
(in response to JITINDER CHOUDHARY)

Hey there

   Actually those are two different scenarios, the key lies in how the values are stored, here's the detail:

ZPARM values are stored by assembling the corresponding macro, therefore if you change it through CA tools the effect will only last until the next Db2 restart. If you want to make it official you have to either edit DSNTIJUZ and submit it or go through the official CLIST DSNTIDxx and then the update panels (which will in turn create another DSNTIJUZ ready to be submitted, and I didn't mention it last time, but I always use this options to have an updated DSNTIDxx member, which wouldn't happen if you directly edit DSNTIJUZ).

Bpool info, on the other hand, is stored on the BSDS, that's why you usually use the command. Usually I would also issue the command and then track the changes using CA Sysview for Db2 to see how that threshold is behaving along with the others, but for ease of use, using CA tools to change the Bpool threshold works great.

Lastly, what I meant by giving more detail is that tuning Bpools is more like an art and perhaps you will end up taking more actions than just updating that specific Bpool threshold. More details would allow us to give more recommendations.

Hope that helps :)

Regards,

Javier Estrada Benavides, Mexico

IBM Champion

IBM Certified System Administrator - DB2 11 for z/OS

IBM Certified Database Administrator - DB2 11 DBA for z/OS