Removed files but filesystem usage still 100%

One filesystem dedicated to Oracle exports.
This system has been around for many years and filesystem usage is generally around 75%.
Normally, export files are created, written to tape and then deleted.

Puzzled why one day we had ended up with 100% usage - what seems to have happened is:

• Export ran and completed
• Backup started (for whatever reason it didn’t finish)
• Export ran and started to overwrite (delete and recreate) the export file
• Backup still had the export file open so delete succeeded but space was not released.

I used lsof to identify open files:

[root@ora1 log]# lsof | grep export
vbda 19182 root 6r  DIR 120,193 4096 2 /oradata/export
vbda 19182 root 7r  REG 120,193 243816632320 18 /oradata/export/exp.dmp (deleted)
bash 25957 ora  cwd DIR 120,193 4096 2 /oradata/export

The second column in lsof output is the owning PID - in this case it was the old backup process.

Killed the backup process, space was released and things returned to normal.