If I have an oracle 9 database environment on a san running solaris 5.8 as the os. Can I plug the san into a Solaris 5.9 environment and have the database work ? - as long as binaries are on the san
By binaries do you mean the binary database image or the executables?
I would recommend that you have the executables on local disk but have the database on the san.
Also, Oracle is a complex product and has to be tuned with the operating system. I would do a separate install of oracle on the 5.9 box, and ensure that only have one oracle has the database open at a time.
You would need to check with the Oracle documentation to see if you need to migrate the database itself, but I am assuming the version of Oracle is not changing.
As always, ensure adequate backup prior to any activity like this.