I'm on Oracle Linux 7.I used cryptsetup to create block device and mounted it(shown as /dev/mapper/damo3 mounted on /mnt/vldsk_damo3 in the picture). To test its IO, I used sysbench to fill it to 50GB.Afterwards, I rmed all the files inside /mnt/vldsk_damo3, and then suddenly /dev/mapper/ol-root and /dev/mapper/ol-home showed up, and /dev/mapper/ol-root is taking up 50GB. I have no idea how to free that.Can someone help me explain what has happened here?UPDATE 1:I kinda figured out where the 50GB is being held.It's being held in the image file for /dev/mapper/damo3.So apparently, deleting files in the disk does not shrink the size of encrypted data on the image file??And also strangely, as you can see in the second image, while the image file size is 80GB, the contents are apparently 50GB? I'm not exactly sure how that is possible.UPDATE 2:Even when I deleted that image file (damo3), that /dev/mapper/ol-root still has 50Gb. I don't understand...UPDATE 3:After rebooting after update2, most of /dev/mapper/ol-root shrunk. I still don't know why.
Why does /dev/mapper/ol-root not empty out space after deleting files?
filesystems;mount;dm crypt;cryptsetup;device mapper