I found a documentation which describes how to disable the sync mount options
of
a subfs mounted device.
http://portal.suse.de/sdb/de/2005/06/dkukawka_halnosync_html.htmlhttps://bugzilla.novell.com/show_bug.cgi?id=85413#c5Mounting hotplugged devices without "sync"
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If writing to USB storage devices like USB sticks or USB hard drive is
rather slow or if you do not want synchronized writing to these devices,
disable the sync mount option.
1.
Create the directory /usr/share/hal/fdi/policy/95userpolicy:
mkdir -p /usr/share/hal/fdi/policy/95userpolicy/
2.
Create a file with the name nosync.fdi and the following contents:
vi /usr/share/hal/fdi/policy/95userpolicy/nosync.fdi
<?xml version="1.0" encoding="UTF-8"?>
<deviceinfo version="0.2">
<device>
<!-- disable sync for mount -->
<match key="block.is_volume" bool="true">
<match key="volume.fsusage" string="filesystem">
<match key="volume.uuid" string="==UUID==">
<merge key="volume.policy.mount_option.sync"
type="bool">false</merge>
</match>
</match>
</match>
</device>
</deviceinfo>
3.
Adjust the line <match key="volume.uuid" string="==UUID=="> according to
your hardware. Run 'lshal' to retrieve the "volume.uuid" and enter this id
instead of ==UUID==
4.
Finally restart the HAL service with
rchal restart