This example shows how you can fully configure for the
automatic addition of more space by changing some configuration parameter
settings, changing the frequency of a task that monitors low storage,
and specifying information for extendable spaces and chunks.
To configure for the automatic addition of more storage
space:
- Add entries to the storage pool.
For example,
add the $INFORMIXDIR/tmp directory to the storage
pool, as follows:
DATABASE sysadmin;
EXECUTE FUNCTION task("storagepool add", "$INFORMIXDIR/tmp",
"0", "0", "10000", "2");
- Mark some chunks in unmirrored dbspaces and temporary dbspaces
as extendable so that the server can extend the chunks if necessary
in the future.
For example, specify that chunk 12 can
be extended:
EXECUTE FUNCTION task("modify chunk extendable", "12");
You
can also change the mark to of an extendable chunk to not extendable.
For example, specify that chunk number 10 cannot be extended:
EXECUTE FUNCTION task("modify chunk extendable off", "10");
- In the SP_THRESHOLD configuration parameter, set a threshold
for the minimum amount of free KB that can exist in a storage space
before Informix® automatically
runs a task to expand the space. Specify either:
- A value from
1
to 50
for a percentage,
- A value from
1000
to the maximum size of the
chunk in KB
If an individual storage space fills beyond this threshold
that you define and remains that full until the space-monitoring task
(mon_low_storage) next runs, the server attempts to expand
the space by extending an extendable chunk or by using the storage
pool to add a chunk.
For example, suppose the SP_THRESHOLD value
is 5.5, which the server treats as 5.5 percent. If a space runs low
on free pages, and the free space percentage falls below 5.5 percent
and remains below that level until the mon_low_storage task
runs next, that task attempts to expand the space. If SP_THRESHOLD
is set to 50000 and a space has fewer than free 50000 KB, that space
is expanded the next time mon_low_storage runs.
- Optional: Change how often the mon_low_storage task
runs. This task periodically scans the list of dbspaces to find spaces
that fall below the threshold indicated by SP_THRESHOLD configuration
parameter.
For example, to configure the task to run
every 10 minutes, run the following SQL statements:
DATABASE sysadmin;
UPDATE ph_task set tk_frequency = INTERVAL (10) MINUTE TO MINUTE
WHERE tk_name = “mon_low_storage”;
- Optional: Change the value of the SP_WAITTIME
configuration parameter, which specifies the maximum number of seconds
that a thread waits for a space to expand before returning an out-of-space
error.
- Optional: Change two sizes that are associated
with expanding a storage space:
- The
extend size, which is the minimum size that is used when extending
a chunk in a dbspace, temporary dbspace, or the plogspace
- The create size, which is the minimum size that is used when
creating a new chunk in a dbspace, temporary dbspace, sbspace, temporary
sbspace, or blobspace that is not a mirror space
For example, the
following command sets the create size and extend size to 60 MB and
10 MB, respectively, for space number 3:
EXECUTE FUNCTION task("modify dbspace sp_sizes",
"3", "60000", "10000");
After you configure for the automatic expansion of a storage
space, you can also manually expand the space or extend a chunk in
the space, as necessary.