Concurrent I/O for NFS

With CIO, application reads and writes that are issued concurrently run concurrently without reads blocking for the duration of writes, or the reverse.

Multiple writes also run concurrently. POSIX atomicity guarantees are not provided. When CIO is in effect, direct I/O is implied. Use the AIX cio mount option or the O_CIO open() flag to set CIO. For more information about CIO, see the -o option for the mount command.

In AIX Version 6.1 with the 6100-04 Technology Level and later, you can run the mount command, the nfs4cl command, or the open() subroutine to allow you to open read only files when those file have already been opened in CIOR. The cior mount option and the O_CIOR open () flag can only be used in conjunction with CIO.