configuration advisor on buffer pool size

[xixi]

hi, we are using db2 udb v8.1 on windows, i try to use the
configuration advisor to get recommendation on the parameter setting,
at first, i give the target memory for DB2 is 80% of the physical
memory, it gives me a recommendation on bufferpool size, so i accept
the change, later on , i found that i gave too much memory to DB2, so
i change the target lower, but the recommendation doesn't change the
buffer pool size accordingly, why is that? thanks

[Pierre Saint-Jacques]

Xixi, I believe that when you say it does not change, you are still
looking at the value through the COnfigure Parameters option in the
COntrol Center.
This application, when it opens, snapshots the DB CFG and picks the
values it reads. When you run the Advisor output, you change the actual
file with the immediate or deferred option, and the old value is still
cached and displayed.
If you look at the size of the bp using the Buffer Pools object in the
db drop down on the control center you should see the new value. If
not, just refresh the the buffwer pool object.
Or, if you do not mind, just close the CC and reopen it. Go to the
Configure parameters and you shouyld see your new value.
HTH, Pierre.

xixi wrote:

hi, we are using db2 udb v8.1 on windows, i try to use the
configuration advisor to get recommendation on the parameter setting,
at first, i give the target memory for DB2 is 80% of the physical
memory, it gives me a recommendation on bufferpool size, so i accept
the change, later on , i found that i gave too much memory to DB2, so
i change the target lower, but the recommendation doesn't change the
buffer pool size accordingly, why is that? thanks

--
Pierre Saint-Jacques - Reply to: sesconsjunk at attglobaljunk dot com
Reconstruct address: Remove the two junk and replace at and dot by
their symbols.
IBM DB2 Cerified Solutions Expert - Administration
SES Consultants Inc.

[Pierre Saint-Jacques]

Xixi, I believe that when you say it does not change, you are still
looking at the value through the COnfigure Parameters option in the
COntrol Center.
This application, when it opens, snapshots the DB CFG and picks the
values it reads. When you run the Advisor output, you change the actual
file with the immediate or deferred option, and the old value is still
cached and displayed.
If you look at the size of the bp using the Buffer Pools object in the
db drop down on the control center you should see the new value. If
not, just refresh the the buffwer pool object.
Or, if you do not mind, just close the CC and reopen it. Go to the
Configure parameters and you shouyld see your new value.
HTH, Pierre.

xixi wrote:

hi, we are using db2 udb v8.1 on windows, i try to use the
configuration advisor to get recommendation on the parameter setting,
at first, i give the target memory for DB2 is 80% of the physical
memory, it gives me a recommendation on bufferpool size, so i accept
the change, later on , i found that i gave too much memory to DB2, so
i change the target lower, but the recommendation doesn't change the
buffer pool size accordingly, why is that? thanks

--
Pierre Saint-Jacques - Reply to: sesconsjunk at attglobaljunk dot com
Reconstruct address: Remove the two junk and replace at and dot by
their symbols.
IBM DB2 Cerified Solutions Expert - Administration
SES Consultants Inc.

[xixi]

it doesn't change because the Configuration advisor didn't give a
recommendation value for new buffer pool size just like for other
parameters, cause i could see that. even i close the control center
and reopen it, it still display the size which use 80% memory, not the
new target memory. thanks

[xixi]

it doesn't change because the Configuration advisor didn't give a
recommendation value for new buffer pool size just like for other
parameters, cause i could see that. even i close the control center
and reopen it, it still display the size which use 80% memory, not the
new target memory. thanks

[Pierre Saint-Jacques]

I think I got confused.
If you say it still shows 80% od memory, then it is working as expected.
The Advisor opens on the premise that you are running a dedicated
system, one instance owning one database.
Given that, it will always open recommending using 80% of leftover
memory for the db.
Even if you execute the Advisor recommendations and reopen the Advisor,
the 80 % value will still show up, independent of any choices you made
while choosing and running the advisor output.
I also think, not sure, that if you change the 80% with the slider and
set it to 70% for example, when you reopen the advisor after running it,
it will come and show an 80% value again.
HTH, Pierre.

xixi wrote:

it doesn't change because the Configuration advisor didn't give a
recommendation value for new buffer pool size just like for other
parameters, cause i could see that. even i close the control center
and reopen it, it still display the size which use 80% memory, not the
new target memory. thanks

--
Pierre Saint-Jacques - Reply to: sesconsjunk at attglobaljunk dot com
Reconstruct address: Remove the two junk and replace at and dot by
their symbols.
IBM DB2 Cerified Solutions Expert - Administration
SES Consultants Inc.

[Pierre Saint-Jacques]

I think I got confused.
If you say it still shows 80% od memory, then it is working as expected.
The Advisor opens on the premise that you are running a dedicated
system, one instance owning one database.
Given that, it will always open recommending using 80% of leftover
memory for the db.
Even if you execute the Advisor recommendations and reopen the Advisor,
the 80 % value will still show up, independent of any choices you made
while choosing and running the advisor output.
I also think, not sure, that if you change the 80% with the slider and
set it to 70% for example, when you reopen the advisor after running it,
it will come and show an 80% value again.
HTH, Pierre.

xixi wrote:

it doesn't change because the Configuration advisor didn't give a
recommendation value for new buffer pool size just like for other
parameters, cause i could see that. even i close the control center
and reopen it, it still display the size which use 80% memory, not the
new target memory. thanks

--
Pierre Saint-Jacques - Reply to: sesconsjunk at attglobaljunk dot com
Reconstruct address: Remove the two junk and replace at and dot by
their symbols.
IBM DB2 Cerified Solutions Expert - Administration
SES Consultants Inc.

[xixi]

when i use the configuration advisor, the first screen come up with a
slide bar as target memory 80%, then i take it and finish the rest of
the steps, it gives me recommendation on the bufferpool size , e.g.
4000000 (about 2g) , so i accept it. later on the same server(windows
2003) has to hold app server and the database server at the same time,
and also i have two databases being used under same instance, so i
decided to use the configuration advisor change the target memory, the
first screen still come up with 80% target, i slide the bar to use
40%, finish the rest of steps, then i saw the recommendation for the
bufferpool size doen't change , still 4000000, that is why confusing
me. why the new update on the memory is not reflected?

[xixi]

when i use the configuration advisor, the first screen come up with a
slide bar as target memory 80%, then i take it and finish the rest of
the steps, it gives me recommendation on the bufferpool size , e.g.
4000000 (about 2g) , so i accept it. later on the same server(windows
2003) has to hold app server and the database server at the same time,
and also i have two databases being used under same instance, so i
decided to use the configuration advisor change the target memory, the
first screen still come up with 80% target, i slide the bar to use
40%, finish the rest of steps, then i saw the recommendation for the
bufferpool size doen't change , still 4000000, that is why confusing
me. why the new update on the memory is not reflected?

[Pierre Saint-Jacques]

That the buffer pool value 4000000 (4M pages ???) does not change after
you new specs. has me confused.
Is it really 4,000,000 pages??? That really is 16 GB of memory and
you'd absolutely need t run on a 64 bit system for this.

If you set it at 4MB or 1000 pages then it should not change even if you
only claim 40% of memeory on the second run of your advisor.

Torestate, I do not think that the Advisor changes the 80% claim when it
starts for every time it runs. I do not think that there's a paramater
that will remeber you chose 60% one time, 40% another and so on. It
just comes up with 805 each time and lets you reset.
HTH, Pierre.

xixi wrote:

when i use the configuration advisor, the first screen come up with a
slide bar as target memory 80%, then i take it and finish the rest of
the steps, it gives me recommendation on the bufferpool size , e.g.
4000000 (about 2g) , so i accept it. later on the same server(windows
2003) has to hold app server and the database server at the same time,
and also i have two databases being used under same instance, so i
decided to use the configuration advisor change the target memory, the
first screen still come up with 80% target, i slide the bar to use
40%, finish the rest of steps, then i saw the recommendation for the
bufferpool size doen't change , still 4000000, that is why confusing
me. why the new update on the memory is not reflected?

--
Pierre Saint-Jacques - Reply to: sesconsjunk at attglobaljunk dot com
Reconstruct address: Remove the two junk and replace at and dot by
their symbols.
IBM DB2 Cerified Solutions Expert - Administration
SES Consultants Inc.