This is still very primitive support of drbd in lvm2.
Can we use some /sys information for this ?
Index: LVM2.2.02.39/lib/cache/lvmcache.c
===================================================================
--- LVM2.2.02.39.orig/lib/cache/lvmcache.c	2008-06-27 23:18:31.000000000 +0800
+++ LVM2.2.02.39/lib/cache/lvmcache.c	2009-03-31 12:08:29.000000000 +0800
@@ -1119,6 +1119,13 @@
 						 pvid, dev_name(dev),
 						 dev_name(existing->dev));
 				return NULL;
+			} else if (MAJOR(existing->dev->dev) == drbd_major() &&
+					MAJOR(dev->dev) != drbd_major()) {
+				log_very_verbose("Ignoring duplicate PV %s on "
+						"%s - using drbd %s",
+						pvid, dev_name(dev),
+						dev_name(existing->dev));
+				return NULL;
 			} else if (MAJOR(existing->dev->dev) != md_major() &&
 				   MAJOR(dev->dev) == md_major())
 				log_very_verbose("Duplicate PV %s on %s - "
@@ -1131,6 +1138,12 @@
 						 "using dm %s", pvid,
 						 dev_name(existing->dev),
 						 dev_name(dev));
+			else if (MAJOR(existing->dev->dev) != drbd_major() &&
+					MAJOR(dev->dev) == drbd_major())
+				log_very_verbose("Duplicate PV %s on %s - "
+						"using drbd %s", pvid,
+						dev_name(existing->dev),
+						dev_name(dev));
 			/* FIXME If both dm, check dependencies */
 			//else if (dm_is_dm_major(MAJOR(existing->dev->dev)) &&
 				 //dm_is_dm_major(MAJOR(dev->dev)))
Index: LVM2.2.02.39/lib/filters/filter.c
===================================================================
--- LVM2.2.02.39.orig/lib/filters/filter.c	2009-03-31 11:48:52.000000000 +0800
+++ LVM2.2.02.39/lib/filters/filter.c	2009-03-31 11:57:38.000000000 +0800
@@ -46,12 +46,20 @@
 
 static int _md_major = -1;
 static int _device_mapper_major = -1;
+static int _drbd_major = -1;
 
 int md_major(void)
 {
 	return _md_major;
 }
 
+/* FIXME: Should we consider filter out non-primary
+   drbd resource ?? */
+int drbd_major(void)
+{
+	return _drbd_major;
+}
+
 /*
  * Devices are only checked for partition tables if their minor number
  * is a multiple of the number corresponding to their type below
@@ -208,6 +216,9 @@
 		if (!strncmp("md", line + i, 2) && isspace(*(line + i + 2)))
 			_md_major = line_maj;
 
+		if (!strncmp("drbd", line + i, 4) && isspace(*(line + i + 4)))
+			_drbd_major = line_maj;
+
 		/* Look for device-mapper device */
 		/* FIXME Cope with multiple majors */
 		if (!strncmp("device-mapper", line + i, 13) && isspace(*(line + i + 13)))