[Bug 20717] Improve async/sync writing behaviour for removable devices

[Martin Pitt]

Public bug report changed:
https://launchpad.net/malone/bugs/20717

Comment:
Wrt. performance, the difference between sync and async is a magnitude
(factor 10 to 100, depending on the application).

I am aware that the unmounting behaviour should be greatly improved, and
we already have an open bug about this (bug 32643), which will be fixed
for Dapper.

Thanks,

Martin