doc: add a note about device filtering while lvmetad is used

diff --git a/conf/example.conf.in b/conf/example.conf.in
index b99f010406671252521a35c7a6d2de480ad21274..fb96079312050314bdfd9db3ec8c239f14336664 100644 (file)
--- a/conf/example.conf.in
+++ b/conf/example.conf.in
@@ -80,6 +80,8 @@ devices {
     # the cache file gets regenerated (see below).
     # If it doesn't do what you expect, check the output of 'vgscan -vvvv'.
 
+    # If lvmetad is used, then see "A note about device filtering while
+    # lvmetad is used" comment that is attached to global/use_lvmetad setting.
 
     # By default we accept every block device:
     filter = [ "a/.*/" ]
@@ -559,6 +561,16 @@ global {
     # that appear in the system. Once the VG is complete (all the PVs are
     # present), it is auto-activated. The activation/auto_activation_volume_list
     # setting controls which volumes are auto-activated (all by default).
+    #
+    # A note about device filtering while lvmetad is used:
+    # When lvmetad is updated (either automatically based on udev events
+    # or directly by pvscan --cache <device> call), the devices/filter
+    # is ignored and all devices are scanned by default. The lvmetad always
+    # keeps unfiltered information which is then provided to LVM commands
+    # and then each LVM command does the filtering based on devices/filter
+    # setting itself.
+    # To prevent scanning devices completely, even when using lvmetad,
+    # the devices/global_filter must be used.
     use_lvmetad = 0
 
     # Full path of the utility called to check that a thin metadata device

diff --git a/man/pvscan.8.in b/man/pvscan.8.in
index 78ee3e2119a449781ee4f1f7ed100eb5b861608b..211c82babfa33b0d5a613ab227c34ee17486e509 100644 (file)
--- a/man/pvscan.8.in
+++ b/man/pvscan.8.in
@@ -59,7 +59,8 @@ Run the command in the background.
 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 in lvm.conf.
+filters set using \fBdevices/filter\fP configuration setting. To filter
+devices even in this case, the \fBdevices/global_filter\fP must be used.
 .SH SEE ALSO
 .BR lvm (8),
 .BR pvcreate (8),