lvmsar: add page (#18169)

Author: ali90h

pages/linux/lvmsar.md

@@ -0,0 +1,16 @@
+# lvmsar
+
+> LVM system activity reporter (not supported under LVM2; prefer `dmstats`).
+> More information: <https://manned.org/lvmsar>.
+
+- Run the legacy reporter (LVM1 systems only):
+
+`lvmsar`
+
+- Report I/O statistics for a device using device-mapper stats:
+
+`dmstats report {{/dev/mapper/device}}`
+
+- List statistics regions for a device:
+
+`dmstats list {{/dev/mapper/device}}`