1) Nein, nicht in dieser Größenordnung.
2) Ja , bereits durchgeführt.
Ich habe von btdu inzwischen eine Meldung erhalten:
--- Explanation:
This node represents samples in files for which btrfs provided an inode, but responded with "not found" when attempting to look up filesystem paths for the given inode.
One likely explanation is files which are awaiting deletion, but are still kept alive by an open file descriptor held by some process. This space could be reclaimed by killing the respective tasks or restarting the system.
More precisely, this node represents samples for which BTRFS_IOC_INO_PATHS returned ENOENT.
Allerdings hilft mir das nicht wirklich weiter.