diff --git a/userspace/marsadm b/userspace/marsadm
index 3573ee10..8e87333e 100755
--- a/userspace/marsadm
+++ b/userspace/marsadm
@@ -2777,10 +2777,12 @@ sub wait_cluster {
 }
 
 sub wait_cluster_noforce {
-  my ($cmd, $res) = @_;
+  my ($cmd, $res, $hosts) = @_;
   if (!$force) {
-    lprint "WAITING for communication\n" if $verbose;
-    wait_cluster($cmd, $res, "*", 0);
+    $res = "all" if (!$res || $res =~ m/,/);
+    $hosts = "*" unless $hosts;
+    lprint "WAITING for communication with '$hosts'\n" if $verbose;
+    wait_cluster($cmd, $res, $hosts, 0);
   }
 }
 
@@ -4040,6 +4042,16 @@ sub _get_designated_primary {
   return $val;
 }
 
+my %pri_new;
+
+sub _get_future_primary {
+  my ($cmd, $res, $unchecked) = @_;
+  if ($pri_new{$res}) {
+    return $pri_new{$res};
+  }
+  return _get_designated_primary(@_);
+}
+
 sub is_actual_primary {
   my ($cmd, $res, $peer) = @_;
   $peer = $host unless (defined($peer) && $peer);
@@ -6431,6 +6443,9 @@ sub primary_phase0 {
     }
   }
   lprint "Current designated primary: $old\n";
+  lprint "Future  designated primary: $new\n";
+  $pri_old{$res} = $old;
+  $pri_new{$res} = $new;
   if ($cmd =~ m/primary/) {
     if ($host ne $old) {
       lprint "Allowing handover in cases of sync: ignore_sync=$ignore_sync\n" if $ignore_sync;
@@ -6518,7 +6533,7 @@ sub primary_phase0 {
 # otherwise: prepare prosumers
 sub primary_phase0a {
   my ($cmd, $res) = @_;
-  my $new = $host;
+  my $new = $pri_new{$res};
   if (!$force && $cmd =~ m/primary/) {
     lprint "Prepare new primary '$new' handover\n";
     _switch($cmd, $res, "$mars/resource-$res/todo-$new/fetch", 1);
@@ -6715,8 +6730,8 @@ sub primary_phase1b {
   return 0 if $force;
   my $check_logger = 0;
   my $this_stamp = 0;
-  my $old = _get_designated_primary($cmd, $res, -1);
-  my $new = $host;
+  my $old = $pri_old{$res};
+  my $new = $pri_new{$res};
   if (todo_local(@_)) {
     my $status = check_primary_gone($cmd, $res, $old);
     return $status if $status;
@@ -6824,9 +6839,8 @@ sub primary_phase2b {
 sub primary_phase3 {
   my ($cmd, $res) = @_;
   return 0 unless $cmd =~ m/primary/;
-  my $old = _get_designated_primary($cmd, $res, -1);
-  $pri_old{$res} = $old;
-  my $new = $host;
+  my $old = $pri_old{$res};
+  my $new = $pri_new{$res};
   _primary_res($res, $new, $old);
   $allow_fail_action = \&compensate_primary_fail_switched;
   my $prosumers = get_prosumers(@_);
@@ -6902,6 +6916,7 @@ sub primary_phase3c {
     $allow_fail_action = \&compensate_primary_fail_prepared;
     _trigger(3);
   }
+  return 0;
 }
 
 # wait for prosumer-handover finished
@@ -6909,7 +6924,7 @@ sub primary_phase3d {
   my ($cmd, $res) = @_;
   return 0 if $force || todo_local(@_);
   my $old = $pri_old{$res};
-  my $new = $host;
+  my $new = $pri_new{$res};
   my $prosumers = get_prosumers(@_);
   foreach my $peer (split("\\+", $prosumers)) {
     my $lnk = "$mars/resource-$res/actual-$peer/prosumer-on";
@@ -6985,7 +7000,7 @@ sub primary_phase3f {
   my ($cmd, $res) = @_;
   if (!$force && !todo_local(@_)) {
     my $old = $pri_old{$res};
-    my $new = $host;
+    my $new = $pri_new{$res};
     if ($old ne $new) {
       my $lnk = "$mars/resource-$res/actual-$old/is-primary";
       my $val = get_link($lnk, 1);
@@ -7032,12 +7047,14 @@ sub primary_phase4 {
     check_mars_device($cmd, $res, 1, 0);
   } elsif (!$force) {
     my $old = $pri_old{$res};
-    my $new = $host;
-    lprint "Unexporting old primary '$old' for safety.\n";
-    my $lnk = "$mars/resource-$res/todo-$old/exports";
-    set_link("(none)", $lnk);
-    $lnk = "$mars/resource-$res/todo-$old/multi-prosumer";
-    set_link("0", $lnk);
+    my $new = $pri_new{$res};
+    if ($old && $new && $new ne $old && $old ne "(none)") {
+      lprint "Unexporting old primary '$old' for safety.\n";
+      my $lnk = "$mars/resource-$res/todo-$old/exports";
+      set_link("(none)", $lnk);
+      $lnk = "$mars/resource-$res/todo-$old/multi-prosumer";
+      set_link("0", $lnk);
+    }
   }
   # new switch semantics, when nothing has failed before: up
   up_res_phase1(@_);
@@ -7078,19 +7095,34 @@ my %pros_umount;
 
 sub prosumer_phase0 {
   my ($cmd, $res) = @_;
-  my $primary = _get_designated_primary($cmd, $res, 0);
-  lprint "Current designated primary: $primary\n";
-  if ($primary eq "(none)") {
+  my $max_retry = 3;
+ retry:
+  my $old_primary = _get_designated_primary($cmd, $res, 0);
+  my $new_primary = _get_future_primary($cmd, $res, 0);
+  lprint "Current designated primary: $old_primary\n";
+  lprint "Future  designated primary: $new_primary\n";
+  if ($new_primary eq "(none)") {
     my $old_prosumers = _get_prosumer(@_);
     my $new_prosumers = parse_list_spec($cmd_suffix{"prosumer"}, $old_prosumers, $host);
     if ($new_prosumers ne "(local)" && $new_prosumers ne "(none)") {
-      ldie "Cannot activate prosumers '$new_prosumers' when there is no designated primary.\n";
+      if ($max_retry-- > 0) {
+	lwarn "cannot find a designated primary.\n";
+	update_cluster($cmd, $res);
+	goto retry;
+      }
+      ldie "Cannot activate prosumers '$new_prosumers' without a designated primary.\n";
     }
   }
-  if ($primary ne "(none)" &&
-      !is_actual_primary($cmd, $res, $primary)) {
-    ldie "Designated primary '$primary' is not actually primary\n" unless $force;
-    lwarn "CONTINUE AT YOUR RISK, although designated primary '$primary' is not actually primary\n";
+  if ($old_primary ne "(none)" &&
+      !is_actual_primary($cmd, $res, $old_primary)) {
+    if ($max_retry-- > 0) {
+      lwarn "current designated primary '$old_primary' is not actually primary\n";
+      sleep(1);
+      wait_cluster_noforce($cmd, $res, $old_primary);
+      goto retry;
+    }
+    ldie "Designated primary '$old_primary' is not actually primary\n" unless $force;
+    lwarn "CONTINUE AT YOUR RISK, although current designated primary '$old_primary' is not actually primary\n";
   }
 
   my $old_prosumers = _get_prosumer(@_);
@@ -7109,8 +7141,8 @@ sub prosumer_phase0 {
     $old_prosumers = "";
     $old_means .= " means ''";
   } elsif ($old_prosumers eq "(local)") {
-    $old_prosumers = $primary;
-    $old_means .= " means designated primary '$primary'";
+    $old_prosumers = $new_primary;
+    $old_means .= " means designated primary '$new_primary'";
   }
   if ($new_prosumers eq "(none)") {
     $new_prosumers = "";
@@ -7205,7 +7237,7 @@ sub prosumer_phase0 {
 
 sub prosumer_phase1 {
   my ($cmd, $res) = @_;
-  my $primary = _get_designated_primary($cmd, $res, 0);
+  my $primary = _get_future_primary($cmd, $res, 0);
   my $new_prosumers = $pros_new{$res};
   my $uni_prosumers = $pros_uni{$res};
   my $inter_prosumers = $pros_inter{$res};
@@ -10815,6 +10847,89 @@ my %cmd_table =
        \&prosumer_phase5,
        "set final prosumers",
 
+       "LOOP",
+       \&prosumer_phase6,
+       "wait for device",
+      ],
+   "primary+prosumer"
+   => [
+       "usage: primary=<host_list_1> prosumer=<host_list_2> [<resource_name>]",
+       "       where <host_list_*> is '+'-separated.",
+       "       Operators += and -= are also allowed in place of = .",
+       "Switch both the primary and the prosumer device at the same time.",
+       [
+	\&update_guests,
+       ],
+
+       \&primary_phase0,
+       "check primary preconditions",
+       \&prosumer_phase0,
+       "check prosumer preconditions",
+
+       "FORK",
+       "LOOP",
+       \&prosumer_phase1,
+       "remove old prosumers",
+
+       \&primary_phase0a,
+       "conditionally wait for fetch off",
+
+       "LOOP",
+       \&primary_phase0b,
+       "wait for systemd",
+
+       "LOOP",
+       \&prosumer_phase2,
+       "check that any old prosumers are gone when necessary",
+
+       "LOOP",
+       \&primary_phase1,
+       "leave primary state",
+
+       "LOOP",
+       \&primary_phase1b,
+       "trigger remote",
+
+       "LOOP",
+       \&primary_phase2,
+       "wait for cluster when necessary",
+
+       "LOOP",
+       \&primary_phase2b,
+       "avoid split brain",
+
+       \&primary_phase3,
+       "switch to primary",
+
+       "LOOP",
+       \&primary_phase3b,
+       "trigger remote",
+
+       \&primary_phase3c,
+       "trigger prosumer handover",
+
+       \&prosumer_phase3,
+       "set new prosumers",
+
+       "LOOP",
+       \&primary_phase3d,
+       "wait for prosumer handover and open gate",
+
+       "LOOP",
+       \&primary_phase3e,
+       "wait for gate open and reset old primary exports",
+
+       "LOOP",
+       \&primary_phase3f,
+       "wait for old primary gone",
+
+       "LOOP",
+       \&prosumer_phase4,
+       "check that all old prosumers are finally gone",
+
+       \&prosumer_phase5,
+       "set final prosumers",
+
        "LOOP",
        \&prosumer_phase6,
        "wait for device",