From 00271f41dbff6bfcce1389bd904337c823dc2d64 Mon Sep 17 00:00:00 2001
From: Thomas Lamprecht <t.lamprecht@proxmox.com>
Date: Mon, 5 Jul 2021 14:24:35 +0200
Subject: [PATCH] btrfs: document df weirdness and how to better get usage

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
---
 local-btrfs.adoc | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/local-btrfs.adoc b/local-btrfs.adoc
index d7a94f7..f68e30d 100644
--- a/local-btrfs.adoc
+++ b/local-btrfs.adoc
@@ -214,3 +214,13 @@ UUID=<uuid of your root file system> / btrfs defaults,compress=zstd 0 1
 ----
 
 This change will take effect after rebooting.
+
+Checking Space Usage
+^^^^^^^^^^^^^^^^^^^^
+
+The classic `df` tool may output confusing values for some btrfs setups.
+For a better estimate use the `btrfs filesystem usage /PATH` command, for example:
+
+----
+# btrfs fi usage /my-storage
+----