Btrfs

备份

dosnap 可用于定时备份。

备份到移动硬盘：

sudo btrfs send -p /mnt/_snapshots/%home/{2021-04-30T23-00-57-auto,2021-05-09T23-00-01-auto} | pv |
     sudo btrfs receive /path/to/backupdrive/home

相关程序

以下是一些好用的 Btrfs 相关的程序。

compsize

查看 / 的压缩类型和压缩前后的大小

sudo compsize /

btrfs-heatmap

查看 /mountpoint 的 heatmap

sudo btrfs-heatmap /mountpoint

btrfs-list

查看树形的 snapshot 列表

sudo btrfs quota enable /
# 等待 quota rescan
sudo btrfs-list
sudo btrfs quota disable /

btrfs-diff

查看第二个 subvolume 相对于第一个改变的文件

sudo btrfs-diff /mnt/_snapshots/%home/snap /mnt/@home

脚本如下（拷贝自 https://serverfault.com/a/580264）

set -eu

usage() {
    echo "Usage: $0 <older-snapshot> <newer-snapshot>" >&2
    exit 1
}

[ $# -eq 2 ] || usage "Incorrect invocation"
snapshot_old=$1
snapshot_new=$2

[ -d "$snapshot_old" ] || usage "$snapshot_old does not exist"
[ -d "$snapshot_new" ] || usage "$snapshot_new does not exist"

old_transid=$(btrfs subvolume find-new "$snapshot_old" 9999999)
old_transid=${old_transid#transid marker was }
[ "$old_transid" -gt 0 ] || usage "Failed to find generation for $snapshot_new"

btrfs subvolume find-new "$snapshot_new" "$old_transid" | sed '$d' | cut -f17- -d' ' | sort | uniq