Change the physical-log location and size

You can use the onparams utility to change the location and size of the physical log.

You can move the physical-log file to try to improve performance. When the database server initializes disk space, it places the disk pages that are allocated for the physical log in the root dbspace. You might improve performance by moving the physical log to another dbspace.

You can move the physical log to a dbspace or the plogspace. When the physical log is in the plogspace, the database server increases the size of the physical log as needed to improve performance. When the physical log is in a dbspace, you must manually increase the size of the physical log.

To move the physical log to the plogspace, create the plogspace by running the onspaces -c -P command or the SQL administration API admin() or task() function with the create plogspace argument. To change the location of the plogspace, create a new plogspace. The physical log is moved to the new plogspace and the old plogspace is dropped.

Prerequisites to moving the physical log to a dbspace:
  • Log in as user informix or root on UNIX or as a member of the Informix-Admin group on Windows.
  • Determine whether adequate contiguous space in the target chunk is available by running the oncheck -pe command.

    The space that is allocated for the physical log must be contiguous. When you change the physical log size or location, if the target dbspace does not contain adequate contiguous space, the server does not change the physical log. Additionally, if insufficient resources for the physical log exist when you initialize the database server, the initialization fails. The dbspace must use the default page size.

To move the physical log to a dbspace, run the onparams -p -s command or the SQL administration API admin() or task() function with the create dbspace argument.

The following example changes the size and location of the physical log. The new physical-log size is 400 KB, and the log is in the dbspace6 dbspace:
onparams -p -s 400 -d dbspace6 

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