Change default for DRBD barriers
Change default for DRBD barriers

Commit 8a69b3a8 changed the DRBD barriers disabled by default if
“--disable-drbd-barriers” is used to “bfd”, where “d” stands for
disk-drain. DRBD's upstream updated their documentation[1] to
say disk drains should always be used.

[1] http://git.drbd.org/?p=drbd-8.3.git;a=commit;h=f952dcfed57acf

Signed-off-by: Michael Hanselmann <68b67885ff74281219b4a4be33cc20fd45078d7c@google.com>
Reviewed-by: René Nussbaumer <bc755ac45a0e799d1d490cba76febc56d80cc5fc@google.com>

dimara/ganeti,mbakke/ganeti,andir/ganeti,apyrgio/ganeti,grnet/snf-ganeti,bitemyapp/ganeti,apyrgio/snf-ganeti,yiannist/ganeti,leshchevds/ganeti,mbakke/ganeti,andir/ganeti,ganeti/ganeti,yiannist/ganeti,ganeti/ganeti,leshchevds/ganeti,ganeti/ganeti,leshchevds/ganeti,yiannist/ganeti,ganeti-github-testing/ganeti-test-1,ganeti-github-testing/ganeti-test-1,apyrgio/snf-ganeti,bitemyapp/ganeti,apyrgio/ganeti,mbakke/ganeti,onponomarev/ganeti,andir/ganeti,onponomarev/ganeti,grnet/snf-ganeti,dimara/ganeti