vgcfgbackup: add page (#17844)

pages/linux/vgcfgbackup.md

@@ -0,0 +1,24 @@
+# vgcfgbackup
+
+> Back up volume group configuration metadata to files (not user data).
+> More information: <https://manned.org/vgcfgbackup>.
+
+- Back up metadata for all volume groups (to `/etc/lvm/backup/` by default):
+
+`vgcfgbackup`
+
+- Back up metadata for a specific volume group:
+
+`vgcfgbackup {{vg_name}}`
+
+- Write the backup to a specific file:
+
+`vgcfgbackup {{[-f|--file]}} {{path/to/backup}} {{vg_name}}`
+
+- Back up multiple VGs using a filename template (`%s` becomes the VG name):
+
+`vgcfgbackup {{[-f|--file]}} {{/tmp/vg-backup-%s}} {{vg1 vg2 ...}}`
+
+- Increase verbosity (repeat `-v` for more detail):
+
+`vgcfgbackup {{[-v|--verbose]}} {{vg_name}}`