Unmounting a volume with open file handles to deleted files without killing the process
Recently we've been turning on compression in our Oracle databases because it saves us a ton of disk space and actually improves the performance of the databases. Among other things the process involves writing the newly compressed tablespaces to new data files (the systems in question are not using ASM). Because we're moving the DB's from where they are, that gives us the opportunity to do some housecleaning before moving them back, such as un-mounting, checking and possibly resizing the existing filesystems. Occasionally it will occur that after the data has been migrated away and the old data files deleted, that Oracle still has open handles to the deleted files. So the DBA tells me the filesystem is clear and I can have it, but then this happens: [root@kwt-r3oql00 E1Q]# umount /dev/mapper/vg_kwt_r3oql20_s00-oracle_E1Q_sapdata7 umount: /oracle/E1Q/sapdata7: device is busy. (In some cases useful info about processes that use the device is found by lsof(