这非常有信息量，谢谢。
在我尝试 cleanup 之前，Discourse 是否提供了一种无需执行恢复即可验证备份完整性的方法？
du -hx / | sort -h | tail -49 的输出结果（我发现 -h 选项让结果更容易解析）：
833M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/42/fs/var/www/discourse/vendor/bundle/ruby
833M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/42/fs/var/www/discourse/vendor/bundle/ruby/3.4.0
837M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/283/fs/var
837M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/283/fs/var/www
837M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/283/fs/var/www/discourse
837M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/283/fs/var/www/discourse/vendor
837M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/283/fs/var/www/discourse/vendor/bundle
837M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/283/fs/var/www/discourse/vendor/bundle/ruby
837M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/283/fs/var/www/discourse/vendor/bundle/ruby/3.4.0
839M /var/discourse/shared
839M /var/discourse/shared/standalone
840M /var/discourse
863M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/42
863M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/42/fs
868M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/283
868M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/283/fs
874M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/284
874M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/284/fs
874M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/43
874M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/43/fs
908M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/263/fs/usr
925M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/22/fs/usr
944M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/263
944M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/263/fs
961M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/22
961M /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/22/fs
1.3G /usr
1.4G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/251
1.4G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/251/fs
1.4G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/251/fs/var
1.4G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/251/fs/var/www
1.4G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/251/fs/var/www/discourse
1.5G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/227/fs/var
1.5G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/227/fs/var/www
1.5G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/227/fs/var/www/discourse
1.6G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/227
1.6G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots/227/fs
2.5G /var/log
2.5G /var/log/journal
2.5G /var/log/journal/1d9299c9656046d6bd0e18d4a09c183c
2.7G /var/lib/containerd/io.containerd.content.v1.content
2.7G /var/lib/containerd/io.containerd.content.v1.content/blobs
2.7G /var/lib/containerd/io.containerd.content.v1.content/blobs/sha256
9.8G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs
9.8G /var/lib/containerd/io.containerd.snapshotter.v1.overlayfs/snapshots
13G /var/lib
13G /var/lib/containerd
17G /var
20G /
docker volume ls -qf dangling=true 的输出为空。实际上，docker volume ls 也是空的。
docker images -a 的输出：
IMAGE ID DISK USAGE CONTENT SIZE EXTRA
discourse/base:2.0.20260209-1300 50d2dae489a9 4.77GB 1.12GB
discourse/base:2.0.20260521-0047 27373b823bbe 4.89GB 1.17GB
local_discourse/app:latest 01527763be8d 6.9GB 1.63GB U
我对 Docker 的了解不足以诊断这些输出，但如果 /var/log/ 仅包含日志，其大小似乎有点大。另外，我只有一个论坛在运行，却有三个镜像，这很有趣（当然，这也可能是完全正常的）。
感谢您关于增加存储空间的建议。我可能会进行扩容，但在这样做之前，这也是一次很好的学习经历。