diff --git a/lib/cache/lvmetad.c b/lib/cache/lvmetad.c
index 85bbf8824..aec6a7119 100644
--- a/lib/cache/lvmetad.c
+++ b/lib/cache/lvmetad.c
@@ -20,8 +20,6 @@
 #include "lvmcache.h"
 #include "lvmetad-client.h"
 #include "format-text.h" // TODO for disk_locn, used as a DA representation
-#include "format_pool.h" // for FMT_POOL_NAME
-#include "format1.h" // for FMT_LVM1_NAME
 #include "crc.h"
 
 static daemon_handle _lvmetad;
@@ -901,25 +899,28 @@ int lvmetad_pvscan_single(struct cmd_context *cmd, struct device *dev,
 	info = (struct lvmcache_info *) label->info;
 
 	baton.vg = NULL;
-	baton.fid = lvmcache_fmt(info)->ops->create_instance(lvmcache_fmt(info),
-							     &fic);
+	baton.fid = lvmcache_fmt(info)->ops->create_instance(lvmcache_fmt(info), &fic);
 
 	if (!baton.fid)
 		goto_bad;
 
-	lvmcache_foreach_mda(info, _lvmetad_pvscan_single, &baton);
-
-	if (lvmcache_fmt(info) == get_format_by_name(cmd, FMT_POOL_NAME)) {
-		log_error("WARNING: Ignoring old GFS pool metadata on device %s "
-			  "when using lvmetad", dev_name(dev));
+	if (baton.fid->fmt->features & FMT_OBSOLETE) {
+		log_error("WARNING: Ignoring obsolete format of metadata (%s) on device %s when using lvmetad",
+			  baton.fid->fmt->name, dev_name(dev));
 		lvmcache_fmt(info)->ops->destroy_instance(baton.fid);
 		return 0;
 	}
 
-	/* LVM1 VGs have no MDAs. */
-	if (!baton.vg && lvmcache_fmt(info) == get_format_by_name(cmd, FMT_LVM1_NAME))
-		baton.vg = ((struct metadata_area *) dm_list_first(&baton.fid->metadata_areas_in_use))->
-			ops->vg_read(baton.fid, lvmcache_vgname_from_info(info), NULL, 0);
+	lvmcache_foreach_mda(info, _lvmetad_pvscan_single, &baton);
+
+	/*
+	 * LVM1 VGs have no MDAs and lvmcache_foreach_mda isn't worth fixing
+	 * to use pseudo-mdas for PVs.
+	 * Note that the single_device parameter also gets ignored and this code
+	 * can scan further devices.
+	 */
+	if (!baton.vg && !(baton.fid->fmt->features & FMT_MDAS))
+		baton.vg = ((struct metadata_area *) dm_list_first(&baton.fid->metadata_areas_in_use))->ops->vg_read(baton.fid, lvmcache_vgname_from_info(info), NULL, 1);
 
 	if (!baton.vg)
 		lvmcache_fmt(info)->ops->destroy_instance(baton.fid);
diff --git a/lib/format_pool/format_pool.c b/lib/format_pool/format_pool.c
index 0f8f3a3e4..503005a7e 100644
--- a/lib/format_pool/format_pool.c
+++ b/lib/format_pool/format_pool.c
@@ -298,7 +298,7 @@ struct format_type *init_format(struct cmd_context *cmd)
 	fmt->name = FMT_POOL_NAME;
 	fmt->alias = NULL;
 	fmt->orphan_vg_name = FMT_POOL_ORPHAN_VG_NAME;
-	fmt->features = 0;
+	fmt->features = FMT_OBSOLETE;
 	fmt->private = NULL;
 
 	dm_list_init(&fmt->mda_ops);
diff --git a/lib/metadata/metadata-exported.h b/lib/metadata/metadata-exported.h
index 1cce72c44..6a959d18c 100644
--- a/lib/metadata/metadata-exported.h
+++ b/lib/metadata/metadata-exported.h
@@ -122,6 +122,7 @@
 #define FMT_RESTRICTED_READAHEAD 0x00000200U	/* Readahead restricted to 2-120? */
 #define FMT_BAS			0x000000400U	/* Supports bootloader areas? */
 #define FMT_CONFIG_PROFILE	0x000000800U	/* Supports configuration profiles? */
+#define FMT_OBSOLETE		0x000001000U	/* Obsolete format? */
 
 /* Mirror conversion type flags */
 #define MIRROR_BY_SEG		0x00000001U	/* segment-by-segment mirror */
diff --git a/man/pvscan.8.in b/man/pvscan.8.in
index 37ecaafe1..61b15d00c 100644
--- a/man/pvscan.8.in
+++ b/man/pvscan.8.in
@@ -57,13 +57,20 @@ supported for logical volumes that are part of partial or clustered volume group
 .BR \-b ", " \-\-background
 Run the command in the background.
 .TP
-.BR \-\-cache " [" \-\-major " " \fImajor " " \-\-minor " " \fIminor " | " \fIDevicePath " ]..."
+.BR \-\-cache " [" \-\-major " " \fImajor " " \-\-minor " " \fIminor " | " \fIDevicePath " | " \fImajor:minor " ]..."
 Scan one or more devices and instruct the lvmetad daemon to update its cached
 state accordingly.  Called internally by udev rules.
 All devices listed explicitly are processed \fBregardless\fP of any device
 filters set using \fBdevices/filter\fP configuration setting. To filter
 devices even in this case, the \fBdevices/global_filter\fP must be used.
+If lvmetad has not yet cached any metadata or the filters have recently been
+changed, then all devices may be scanned, effectively ignoring the rest of
+the command line.  Otherwise, if all the devices referenced on the command line
+contain metadata in the default lvm2 format, other devices are not accessed.
+If metadata written using the obsolete GFS pool format is encountered, this is
+ignored and so lvmetad should not be used.
 .SH SEE ALSO
 .BR lvm (8),
+.BR lvmetad (8),
 .BR pvcreate (8),
 .BR pvdisplay (8)