O_Direct; Gfs File Attribute - Red Hat GLOBAL FILE SYSTEM 5.1 Manual

Chapter 4. Managing GFS
When a file is opened with
I/O operations must be done in block-size multiples of 512 bytes. The memory being read from
or written to must also be 512-byte aligned.
One of the following methods can be used to enable direct I/O on a file:
•

O_DIRECT

• GFS file attribute

• GFS directory attribute
7.1.
O_DIRECT
If an application uses the
opened file.
To cause the
O_DIRECT
beginning of a source file before any includes, or define it on the cc line when compiling.
7.2. GFS File Attribute
The command can be used to assign (set) a direct I/O attribute flag,
gfs_tool
GFS file. The
directio
Usage
Setting the
directio
gfs_tool setflag directio File
Clearing the
directio
gfs_tool clearflag directio File
File
Specifies the file where the
Example
In this example, the command sets the
.
/gfs1
32
, or when a GFS direct I/O attribute is attached to a file, all
O_DIRECT
flag on an
O_DIRECT
flag to be defined with recent glibc libraries, define
flag can also be cleared.
Flag
Flag
flag is assigned.
directio
directio
system call, direct I/O is used for the
open()
flag on the file named
at the
_GNU_SOURCE
, to a
directio
in directory
datafile