The policy that determines how transaction log file entries are
written to disk. This policy can affect transaction performance.
(Note: To be transactionally safe, the Direct-Write policy may
require additional OS or environment changes on some Windows
systems.)
WebLogic Server supports the following policies:
-
Cache-Flush. Flushes operating system and on-disk caches after
each write.
-
Direct-Write. Tells the operating system to write directly to
disk with each write. Direct-Write performs better than Cache-Flush
and is available on Windows, HP-UX, and Solaris.
If Direct-Write is not supported on the host platform, the
policy becomes Cache-Flush and a log message is printed.
Note: On Windows, unlike
Solaris and HP, the "Direct-Write" policy may leave transaction
data in the on-disk cache without writing it to disk immediately.
This is not transactionally safe because a power failure can cause loss
of on-disk cache data. For transactionally safe writes using
"Direct-Write" on Windows, either disable all write caching for the
disk (enabled by default), or use a disk with a battery-backed
cache.
The on-disk cache for a hard-drive on Windows can be disabled
through system administration: Control-Panel -> System ->
Hardware-tab -> Device-Manager-button -> Disk-Drives ->
name-of-drive -> Policies-tab -> "Enable write caching on the
disk" check-box. Some file systems do not allow this value to be
changed. For example, a RAID system that has a reliable cache.
Default: ServerMBean.SYNCWRITE_DIRECTWRITE