I perform a great many installations of Oracle both RAC and non-rac, in fact, I have installed RAC on over 200 clusters now.  In the process of this I have created silent install processes to help make a cluster install easier on everyone involved.   From time to time, however, the silent install (and sometimes an interactive install) fails with the error “You may not have enough space on your drive for a successful install. Do you still want to continue?”  This is all well and good if interactive as you can say yes or no, but in a silent install all is lost and you will have to start over.

But what causes this error? The obvious is not enough space in the filesystem on which you are installing the Oracle software, but not always.  Oracle typically espects anywhere from 1.6 to 3.5G free on that filesystem depending on product and platform.  You may run into a case where there is plenty of room, so why did it fail?  What the error doesn’t tell you is where the installer is looking for that space.  It is not only your installation (Oracle_base) filesystem, but also /var and /tmp.  If there have been several other installs, successfull or not, Oracle uses /tmp and /var/tmp to store installer information in directories in the format “OraInstallYYYY-MM-DD_HH-MM-SS{AM|PM}.  These directories are not automatically removed at the end of installations and not if an install fails.   Oracle requires typically about 400M in these filesystems, if not found, it will fail with the error above.  So remember to clean out /var/tmp and /tmp after your installations!