RequiresDirFsync
Turn off directory fsync(2) during runtime V8.13 and later
Some versions of Unix (or implementations of disk I/O)
do not support immediate updates of directories when
the data in them changes. For these Unix versions,
the REQUIRES_DIR_FSYNC
compile-time macro
(REQUIRES_DIR_FSYNC on page
136) must set to true, causing sendmail to
fsync(2) the directory every
time it is updated.
If your operating system is one of these, and if you
need to avoid the overhead of this forced directory
updating,[415] you may do so by defining the RequiresDirfsync
option.
It is declared like this:
O RequiresDirfsync=bool ← configuration file (V8.13 and later) -O RequiresDirfsync=bool ← command-line (V8.13 and later) define(`confREQUIRES_DIR_FSYNC', `bool') ← mc configuration (V8.13 and later)
Here, bool
is of type
Boolean. If this option is
omitted, the default is true (that is, directory
fsync(2) is required if
REQUIRES_DIR_FSYNC
was defined at
compile time). If this option is defined as false,
however, directory fsync(2) is
disabled even if REQUIRES_DIR_FSYNC
was defined at
compile-time.
The RequiresDirfsync
option is not safe. If
specified from the command line, it can cause
sendmail to relinquish its special
privileges.
[415] * You risk lost mail should the machine crash without this updating.
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