Hello, I am wondering if it is safe to assume that specifying cio mount option is safe with PostgreSQL. As far as I understand the CIO (AIX Concurrent I/O) means that filesystem does not serialize access to file blocks. In other words multiple threads can simultaneously read and write the file block, which means that it is possible that reader reads stale data. Now, if database enforces its own serialization (and as far as I can tell, bufmgr does it exactly), this option should be totally safe to use, probably giving boost since kernel has less overhead while multiple processes access the database file. Is my thinking correct? Regards, Dawid