DISK INITIALIZATION ABORTED: potential instance overwrite detected

Technote (troubleshooting)


After running oninit -i, IBM Informix Dynamic Server fails to come online and writes the following messages to the message log:

16:06:00 DISK INITIALIZATION ABORTED: potential instance overwrite detected.
To disable this check, set FULL_DISK_INIT to 1 in your config file and retry.

16:06:00 oninit: Fatal error in shared memory initialization

16:06:00 IBM Informix Dynamic Server Stopped.

16:06:00 mt_shm_remove: WARNING: may not have removed all/correct segments


This is expected behavior. It is a feature first put into 11.70.xC1 that prevents the accidental overwrite of an instance which can happen when using the -i (full disk initialization) option. This feature utilizes the onconfig config file parameter FULL_DISK_INIT.

By default, FULL_DISK_INIT is set to 0. This setting protects the ROOTPATH file/device from being overwritten by oninit -i. A value of 1 allows oninit -i to perform full disk initialization (destructive overwrite) of the ROOTPATH file/device.

Resolving the problem

If it is desired to overwrite the ROOTPATH file/device and perform full disk initialization (destructive overwrite), as per the error message above, set the onconfig config file parameter FULL_DISK_INIT to 1 and run oninit -i.

As the server is initializing the instance and the ROOTPATH disk/file, you will see the following messages in the message log:

16:09:48 Value of FULL_DISK_INIT has been changed to 0.
16:11:17 IBM Informix Dynamic Server Initialized -- Complete Disk Initialized.

The first message indicates that the instance is setting the value of FULL_DISK_INIT back to 0 to as a defensive mechanism to prevent a subsequent oninit -i from performing full disk initialization (destructive overwrite). The second message indicates that the instance processes, threads, shared memory segments, memory structures and full disk initialization (destructive overwrite) has completed.

Document information

More support for:

Informix Servers

Software version:

11.7, 12.1

Operating system(s):

AIX, HP-UX, Linux, OS X, Solaris, Windows

Reference #:


Modified date:


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