The sybcluster create cluster command may fail with error -131 and issue a message stating that the parent directory in which the raw devices are defined cannot be accessed:
INFO - Choosing the first instance to be created using the connected agent... ERROR - Parent directory access error. The parent directory /dev/rdsk for the device can not be accessed. Please change the protection on the device and try again. INFO - Create cluster error: -131
You may have incorrectly spelled the name of the raw device. Check the complete name of each raw device and verify that it is correct.