On Fri, Apr 04, 2003 at 07:58:30AM -0700, Sewell, Cassandra D (Cassandra) wrote: > Then are we saying this is possibly a problem in Linux in general, > and has never been fixed. No, it's not a "problem" with Linux. It's always been this way with Unix, and it's not necessarily considered a problem. In Unix if some process has a file open, and that file is subsequently deleted, the process will continue to be able to use the file, and when the process exits, space consumed by that file is deallocated at this time. The directory entry for that file is removed, so that no new process can use this file, and this also means that the du command won't find or see space consumed by that file. However, the space is still in use by the filesystem, so that the process can continue to use the file. This means that this disk blocks are still in use, and this is reflected in the output of the df command. Note that many Unix/Linux programs use this as a feature (it is required by thej POSIX standard) for handling temporary files. They will open a temporary file for scratch space, and then delete it. That way, they the program use the temporary file for its own purposes, but the disk space is automatically reclaimed when the program exits, either normally or abnormally. So as much as you probably hate it when programmers say, "it's a feature, not a bug", in this case, this is absolutely the case. This behaviour has been around for over twenty five years --- it is older than Linux --- and there are various Unix and POSIX standards specifications that absolutely require that we function in this way. You say that you had no applications running, but the space could have been held open by a system daemon. For example, if there was a very large log file which you deleted, but the syslogd daemon was still running, the space wouldn't be reclaimed until you restarted the syslog daemon, since it was holding the file open and hence the space was still in use. I don't know if this is what you did, but I mention it because it is absolutely classic mistake made by beginning Unix system administators. You say that you haven't seen this with other journaled filesystem, but let me assure you that this particular behaviour is shared across all Linux filesystems, and indeed across all Unix-compatible operating systems. I have also not heard of any other case where space has not visible by du and which then "reappeared" when the system was rebooted has been traced down to any thing other than this classic case of system administrator confusion. Is it possible that you've found a bug that no one else in the world as reported and confirmed to date? Quite possibly, but please understand that the symptoms and cure which you reported correspond to the a very common system administrator misunderstanding of how the system works. If you can replicate this problem, I suggest bringing the system down to single user mode. This will kill all off all processes without remounting or rereading the filesystem. I am 99.999% sure that you will then find that all of the space has been reclaimed. - Ted _______________________________________________ Ext3-users@redhat.com https://listman.redhat.com/mailman/listinfo/ext3-users
