CephFS delayed deletion
The deletion of a file does not immediately remove its data. Each of the file’s
underlying objects must be removed independently. If these objects were removed
immediately, the client would have to send
size_of_file / stripe_size *
replication_count messages. This would consume significant bandwith and would
slow the client unacceptably. If snapshots exist, their existence can prevent
the deletion of objects associated with them.
In these cases, such files are (1) marked as deleted on the MDS and (2) deleted lazily.