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public:btrfs_snapshot_size [2016/04/01 01:41]
fangfufu created
public:btrfs_snapshot_size [2018/03/31 01:38] (current)
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 +====== BTRFS snapshot size ======
 +  * First you need to enable quota
 +<code bash>
 +sudo btrfs quota enable /home
 +  * You need to wait for BTRFS so scan the filesystem for quota usage, then
 +<code bash>
 +sudo btrfs qgroup show /home
 +  * You get output which looks like this:
 +qgroupid ​        ​rfer ​        excl
 +-------- ​        ​---- ​        ----
 +0/5         ​142.21GiB ​    ​89.70MiB
 +0/410        96.00KiB ​    ​96.00KiB
 +0/​2191 ​      ​17.62GiB ​       0.00B
 +0/​3237 ​     137.90GiB ​     4.05GiB
 +''​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
 +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
 +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