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--- public:btrfs_snapshot_size [2016/04/01 20:21] – fangfufu
+++ public:btrfs_snapshot_size [2018/03/31 00:38] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+====== BTRFS snapshot size ======
+  * First you need to enable quota
+<code bash>
+sudo btrfs quota enable /home
+</code>
+  * You need to wait for BTRFS so scan the filesystem for quota usage, then
+<code bash>
+sudo btrfs qgroup show /home
+</code>
+  * You get output which looks like this:
+<code>
+qgroupid         rfer         excl
+--------         ----         ----
+/5         142.21GiB     89.70MiB
+/410        96.00KiB     96.00KiB
+/2191       17.62GiB        0.00B
+/3237      137.90GiB      4.05GiB
+</code>
+''qgroupid'' is the snapshot ID, ''rfer'' is the total size of that snapshot (the size of the parent subvolumes are included), ''excl'' is the exclusive space that particular snapshot occupies.
+===== Deleting snapshots =====
+  * You can list all the subvolume by running this:
+<code bash>
+sudo btrfs subvolume list /home
+</code>
+Note that this will display the link between the ''BTRFS_SNAPSHOT_ID'' and ''SNAPPER_SNAPSHOT_ID''.
+  * Note that if you are using snapper, you should delete snapshots using:
+<code bash>
+snapper -c home delete $SNAPPER_ID
+</code>
+You shouldn't delete the snapshot using ''btrfs subvolume delete'', as this will confuse Snapper.
+===== Re-initialise qgroups =====
+If your filesystem has just suffered an episode of catastrophic failure, you might need to re-initialise things. A Snapper rollback can cause it.
+<code bash>
+for i in $(btrfs qgroup show /home | tail -n+3 | cut -d ' ' -f 1); do btrfs qgroup destroy $i /home; done
+btrfs quota disable /home
+btrfs quota enable /home
+</code>