Installation and Initial Configuration 1-43
OnLine Disk Space Allocation

Project Total Space Requirements

The amount of additional disk space needed for OnLine data storage
dependson your production environment. Every application environment is
different.The following list suggests some of the steps you might take to help
youcalculate the amount of disk space to allocate (beyond the root dbspace):
1. Decidehow many databases and tables you need to store. Calculate
the amount of space required for each one.
2. Calculate a growth rate for each table and assign some amount of
disk space to each table to accommodate growth.
3. Decide which databases and/or tables you want to mirror.
Refer toIBM I nformix Guide to SQL: Tutorial for instructions about calculating
the size of your data bases.
After you arrive at a value, enter it on the second page of the configuration
worksheet, in the field labeled Additional disk space for OnLine chunks.
How Should You Apportion Disk Space?
When you allocate disk space (raw disk or cooked files), you allocate it in
unitscalled chunks. A dbspace or a blobspace is associated with one or more
chunks. You must allocate at least one chunk for the root dbspace.
(Refer topage 2-81 for a discussion of the relationships among chunks,
dbspaces, blobspaces, databases, and tblspaces.)
Informix recommends that you format your disk(s) so that each chunk is
associatedwith its own UNIX disk partition. When every chunk is defined as
a separate partition (or device), you will find it is easy to track disk space
usage. You avoid errors caused by miscalculated offsets.
If you are working with a disk that is already partitioned, you might be
required to use offsets to define a chunk.