15.5. Bypassing the Page Cache with Direct I/O
In some cases we may want to do completely unbuffered I/O to a file. A direct I/O facility in most file systems allows a direct file read or write to completely bypass the file system page cache.
15.5.1. UFS Direct I/O
Support for direct I/O was added to UFS starting with Solaris 2.6. Direct I/O allows reads and writes to files in a regular file system to bypass the page cache and access the file at near raw disk performance. Direct I/O can be advantageous when you are accessing a file in a manner where caching is of no benefit. For example, if you are copying a very large file from one disk to another, then it is likely that the file will not fit in memory and you will just cause the system to page ...
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