Utilities And Settings; Write Filter; Write Filter Command Line Control - Wyse WintermTM 9000 Quick Reference Manual

Utilities and Settings

Write Filter

The write filter provides a secure environment for thin-client computing. It does this by
protecting the terminal from undesired flash memory writes (flash memory is where the
operating system and functional software components reside). The write filter also
extends the life of the terminal by preventing excessive flash write activity. It gives the
appearance of read-write access to the flash by employing a cache to intercept all flash
writes and returning success to the process that requested the I/O.
The intercepted flash writes stored in cache are available as long as the terminal remains
active but will be lost when the terminal is rebooted or shut down. To preserve the results
of writes to the registry, favorites, cookies, etc., the contents of the cache can be
transferred ("flushed") to the flash on demand by the Rapport Remote Administration
Software or manually using the Write Filter Control dialog box (see Figure 12) available
from the Control Panel | Administrative Tools | Write Filter selection or through the
Start menu. After the write filter has flushed the cache, all future writes during the current
boot session are written to the flash, with no further caching until a reboot occurs. The
write filter may also be enabled/disabled through the command line or through the Write
Filter Control dialog box. The enabled/disabled status of the write filter is displayed on
the green/red button icon on the task bar system tray (green indicates that the write filter is
active, and red indicates that the write filter is inactive).
The administrator should periodically check the status of the cache. The terminal should
be rebooted if the cache is more than eighty percent full.
The write filter can be manipulated through the command line or the Write Filter Control
dialog box, as follows:

Write Filter Command Line Control

Note
When administering the terminal for permanent changes, to avoid flash
corruption it is strongly recommended flushing the write filter cache
immediately following a fresh reboot before making permanent modifications
to the system. Do not flush the cache if the terminal has been used in the
current boot session.
Caution
The write filter cache should never be flushed if it is eighty-percent or more
full.
Note
Command line arguments cannot be combined.
Caution
Terminal Administrators should use NT file security to prevent undesired
usage of these commands.
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