Esto es muy informativo, gracias.
Antes de intentar cleanup, ¿proporciona Discourse alguna forma de verificar la integridad de la copia de seguridad sin realizar una restauración?
El resultado de du -hx / | sort -h | tail -49 (noté que la opción -h facilitaba la interpretación de los resultados):
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 /
La salida de docker volume ls -qf dangling=true estaba vacía. De hecho, docker volume ls también lo está.
docker images -a:
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
Sé muy poco sobre Docker para diagnosticar esta salida, pero /var/log/ parece un poco grande si solo contiene registros, y es interesante tener 3 imágenes cuando solo tengo 1 foro en ejecución (aunque quizás esto sea totalmente esperado).
Agradezco la observación sobre tener más espacio de almacenamiento. Probablemente lo ampliaré, pero esto ha sido una buena experiencia de aprendizaje antes de hacerlo.