[DRBD-user] Howto define disk-barrier/disk-flushes different on both hosts

[Jasmin J.]

Hi!

I have a machine (A) with a RAID1 and a BBU. On top of a partition of this RAID
is LVM and then DRBD 8.4.

The other machine (B), which is the DRBD mirror for the former mentioned
partition, has a normal SATA disk. I try to use Protocol A, so it makes sense
to configure disk-barrier and disk-flushes different on machine A (quick) and
B (slower).

Here is my config:
resource vm-100-disk-root {
          net {
                  # allow-two-primaries;
                  after-sb-0pri discard-zero-changes;
                  after-sb-1pri discard-secondary;
                  after-sb-2pri disconnect;
          }
          disk {
                  no-disk-barrier;
          }
          volume 0 {
                  device /dev/drbd0;
                  meta-disk internal;
          }
          on serverA {
                  # LVM on top of RAID1
                  disk /dev/vg_vm_disks_A/vm_100_disk_root;
                  address 10.1.0.1:7788;
                  # we have a BBU on the RAID controller, so no flushing
                  # necessary
                  no-disk-flushes;
          }
          on serverB {
                  # /dev/sdc1 normal SATA disk
                  disk /dev/vg_vm_disks_A/vm_100_disk_root;
                  address 10.1.0.2:7788;
                  # this is a local disk without battery and cache
                  disk-flushes;
          }
  }

But this gives:
   $ drbdadm adjust vm-100-disk-root
   drbd.d/vm_100_disk_root.res:22: Parse error: 'disk | device | address |
          meta-disk | flexible-meta-disk' expected, but got 'no-disk-flushes'

So it seems this is the wrong syntax to describe what I want.

Can someone explain if it is possible to define different "disk-flushes"
options to different hosts/disks with another syntax?
If the answer is yes, how can I do this?
If the answer is no, is there a technical reason or simply "not required till
now and therefore not implemented"?

BR,
    Jasmin