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System Architecture 2-15
What Happens During Disk-Space Initialization
Important: Do not initialize disk space without careful consideration. As part of the
procedure, initialization destroys all data on the portion of the disk where the new
root dbspace (and its mirror) will be located.
Here are the main tasks that are completed during disk-space initialization:
1. The tbinit process calculates configuration values.
2. The tbinit daemon creates OnLine shared memory.
3. The tbinit daemon attaches to shared memory.
4. The tbinit daemon initializes shared-memory structures.
5. The tbinit daemon initializes disk space.
6. The tbinit daemon wakes parent tbinit process.
7. The tbinit daemon initiates the first checkpoint.
8. OnLine changes to quiescent mode.
9. The tbinit daemon sets forced residency, if specified.
10. The tbinit daemon begins looping as master daemon.
When you initialize disk space, shared memory is automatically initialized.
However, disk-spaceinitialization does not follow the same steps outlined on
page 2-10. Disk-space initialization and shared-memory initialization are
interrelated but disk-space initialization is more than extra steps added to the
shared-memory initialization procedure.
Step 1: Calculate Configuration Values
The tbinit process reads the configuration values contained in the file
specified by $INFORMIXDIR/etc/$TBCONFIG. If TBCONFIG is not specified,
tbinit reads the values from $INFORMIXDIR/etc/tbconfig.Iftbconfig cannot
be found and TBCONFIG is not set, tbinit reads the values from tbconfig.std.
If TBCONFIG is set but the specified file cannot be accessed, an error message
is returned. Refer to page 1-11 for further information about the OnLine
configuration files.
The tbinit process writes all the values from the configuration file into its
private data space. Then tbinit uses the values to calculate the required size
of OnLine shared memory. In addition, tbinit computes additional configu-
ration requirements from internal values. Space requirements for overhead
are calculated and stored where it is available to tbinit.