Make instance creation ask for 2 nodes, if DRBD is used
Make instance creation ask for 2 nodes, if DRBD is used

In opportunistic locking, we always ask for as many locks
as possible to later chose what fits best. However, we
may also ask for a minimum as otherwise it cannot work
for principle reasons. For DRBD, this minimum should
be two, rather than the default one.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Hrvoje Ribicic <be5828fca31f89218048bec4189e30a581aa65da@google.com>

Cherry-picked from ed94242fdd9947815c84de8b0727aa63630c8f34.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Hrvoje Ribicic <be5828fca31f89218048bec4189e30a581aa65da@google.com>

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