According to the IBM Informix Dynamic Server 9.30.FC1 PRODUCT RELEASE (http://www-3.ibm.com/software/data/informix/pubs/library/notes/machnote/ids_solaris_9_30.txt)
6. Optical
The name of the IBM Informix shared library for Optical on Solaris is
iosm09a.so. This library must be located /usr/lib/sparcv9/iosm09a.so
(or must have a link provided in /usr/lib/sparcv9). Refer to the Guide
to the Optical Subsystem for more information about enabling optical
functionality.
Check that you have the iosm09a.so library installed
Rgds,
axepert (who happens to be facing the same problem too!)