Linux - GeneralThis Linux forum is for general Linux questions and discussion.
If it is Linux Related and doesn't seem to fit in any other forum then this is the place.
Notices
Welcome to LinuxQuestions.org, a friendly and active Linux Community.
You are currently viewing LQ as a guest. By joining our community you will have the ability to post topics, receive our newsletter, use the advanced search, subscribe to threads and access many other special features. Registration is quick, simple and absolutely free. Join our community today!
Note that registered members see fewer ads, and ContentLink is completely disabled once you log in.
If you have any problems with the registration process or your account login, please contact us. If you need to reset your password, click here.
Having a problem logging in? Please visit this page to clear all LQ-related cookies.
Get a virtual cloud desktop with the Linux distro that you want in less than five minutes with Shells! With over 10 pre-installed distros to choose from, the worry-free installation life is here! Whether you are a digital nomad or just looking for flexibility, Shells can put your Linux machine on the device that you want to use.
Exclusive for LQ members, get up to 45% off per month. Click here for more info.
This looks like the infamous "open file deletion" issue.
When you delete a file that is being held "open" by a process what actually happens is the file's name is deleted but not its inode (and its data). df sees what is happening at filesystem level whereas du sees what is happening at file/directory level. If the filename is gone du doesn't see it in the directory any longer. However since the inode is still in use df sees that the filesystem is still using the space.
You can try to run lsof against the filesystem and look for any reg file that has a large size but no name. This will show you the process that has it "open". If you stop then restart the process it will clear the inode. Failing that you can do a reboot which will stop all processes and should definitely clear any such open inodes.
By the way doing a "mv" of a file doesn't help because it keeps the same inode when moved within the filesystem. A "mv" to another filesystem would result in the same situation as the deletion did because such a "mv" actually copies then deletes as the inode is unique to the filesystem it is on.
The most common cause of this is deleting a log file to clear up space. Many log files are held "open" by their applications so deletion should only be done after the application is shutdown. You might want to look at logrotate (man logrotate) to setup automatic aging of logfiles if you have one that is consistently filling up your filesystem.
Last edited by MensaWater; 10-29-2010 at 10:11 AM.
This looks like the infamous "open file deletion" issue.
When you delete a file that is being held "open" by a process what actually happens is the file's name is deleted but not its inode (and its data). df sees what is happening at filesystem level whereas du sees what is happening at file/directory level. If the filename is gone du doesn't see it in the directory any longer. However since the inode is still in use df sees that the filesystem is still using the space.
You can try to run lsof against the filesystem and look for any reg file that has a large size but no name. This will show you the process that has it "open". If you stop then restart the process it will clear the inode. Failing that you can do a reboot which will stop all processes and should definitely clear any such open inodes.
By the way doing a "mv" of a file doesn't help because it keeps the same inode when moved within the filesystem. A "mv" to another filesystem would result in the same situation as the deletion did because such a "mv" actually copies then deletes as the inode is unique to the filesystem it is on.
The most common cause of this is deleting a log file to clear up space. Many log files are held "open" by their applications so deletion should only be done after the application is shutdown. You might want to look at logrotate (man logrotate) to setup automatic aging of logfiles if you have one that is consistently filling up your filesystem.
Hi, I found out the problem and its exactly the same case, one file was deleted while it was used by another process. lsof confirmed that.
Thanks for that simple explanation.
LinuxQuestions.org is looking for people interested in writing
Editorials, Articles, Reviews, and more. If you'd like to contribute
content, let us know.