SAN Mode on Linux Uses Direct Mode

With SAN transport on Linux, read and write operations are performed in “direct” mode (O_DIRECT), meaning that no read or write buffering is done. Direct mode prevents other processes from accessing the latest data, and avoids loss of information if the process dies before committing its write buffers. In direct mode, the most time efficient performance can be achieved if applications follow these guidelines when performing reads and writes. These guidelines are applicable to Windows also.

• The buffer used for data transfer should be aligned on a page boundary.
• The transfer length should be an even multiple of the page size.