IDS Forum

Chunk Auto-expanding

Posted By: Cesar Inacio Martins
Date: Friday, 1 March 2013, at 2:50 p.m.

Hi ,

I'm studying about the auto-expanding feature.
ifx.1170 FC6

Appreciate any help/explanation .

I trying understand how Informix should behave in certain situation and how
I see/do the configuration.

The situation what is my desire to work :
* No storage pool configuration.
* Use only the chunk expanding feature , because on my test environment we
are using cooked file.
* I want the chunk expand 500 MB only when they become full.

The onconfig values of my test environment are :
SP_AUTOEXPAND 1
SP_THRESHOLD 0
SP_WAITTIME 30

I enable the auto-expand for each chunk with the comand task("modify chunks
extendable on "...)
then I change one dbspace configuration with the command task('modify space
sp_size', 9, 0 500000) to configure the expand the chunk with minimal of
500 MB

with onstat -d , the flag E appear for each chunk and all dbspaces show the
flag A .

With this I understand the instance is ready to autoexpand the chunk when
it become full , this is correct ?

Question : There is some way to enable autoexpand for chunks by default
when create them with onspaces?

Question : I was created the dbspaces with onspaces and after that not
apply any other configuration. I suppose the Auto-expand (flag A) is the
default value , what parameter define this default? SP_AUTOEXPAND ?

Question : I read in some place (blog or manual) when the dbspace flag have
A , means they have create/extend size configured with some value diff of
zero. I understand this means the value was set with "modify space
sp_size" command.
So, where/who set this values for the other chunks? since I configure
manually only one.
Looking the sysdbspaces I found this :

dbsnum create_size extend_size

1 10.00000000000 10000.00000000

2 10.00000000000 10000.00000000

3 10.00000000000 10000.00000000

4 10.00000000000 0.00

5 10.00000000000 10000.00000000

6 10.00000000000 10000.00000000

7 10.00000000000 10000.00000000

8 10.00000000000 10000.00000000

9 0.00 500000.0000000

10 10.00000000000 100000.0000000

I not able to identify the origin of 10 and 10000 configured for all
dbspaces...
Where I set this default values for them? (and new dbspaces already assume
the correct default).

Unfortunately the manual isn't clear enough about the relation of all
parameters, default values , admin commands and task schedulers...

Regards
Cesar

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