Date: Mon, 3 Jan 2005 22:10:39 -0600 From: David Kelly <dkelly@HiWAAY.net> To: Gregor Mosheh <stigmata_blackangel@yahoo.com> Cc: FreeBSD_Questions FreeBSD_Questions <freebsd-questions@freebsd.org> Subject: Re: 4.8 - / out of space Message-ID: <97E8FBEA-5E06-11D9-BC68-000393BB56F2@HiWAAY.net> In-Reply-To: <20050104010723.34785.qmail@web53801.mail.yahoo.com> References: <20050104010723.34785.qmail@web53801.mail.yahoo.com>
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On Jan 3, 2005, at 7:07 PM, Gregor Mosheh wrote: > --- David Kelly <dkelly@HiWAAY.net> wrote: > >> Another goof is for root to "write" to an unmounted filesystem. >> Later when the filesystem is mounted the written files are hidden >> yet still consume space on the fs containing the mount point >> (usually /). > > Could you explain how this happens (or point me to a doc)? Do you > mean something like "tar cvf /dev/ad0s1a"? Guessing you quoted the wrong paragraph for the question. As for tar, yes, "tar -cvf /dev/baddevicename myfiles" will happily create a file (not device) named /dev/baddevicename and write the contents of myfiles into it. Iff you have write permission on /dev/. Its no different than "tar -cvf myfiles.tar myfiles" other than you tried to hit a device but created a file instead. As for what I was writing about consider the case where one is running single user and /usr is not yet mounted. A directory named /usr exists. Nothing is preventing root from writing in the /usr directory. This will consume space on / but no longer exist in file namespace once a filesystem is mounted on top of the /usr directory. Files are still there but you can't get to them. > Does that cause fs corruption? Would fsck reclaim that space? No corruption. Fsck is perfectly happy with it and won't change a thing. The stuff hidden under the mount point is still there. The only way to get at it is to umount the fs on top and then the previous contents of /usr reappear. Assuming of course that /usr actually had files underneath. Go read the manpage for mount. Search for "union". Its talking about the same thing as above only a union mount appends the underlying namespace at the end of the mounted filesystem's namespace. Without "union" the underlying namespace is unreachable. -- David Kelly N4HHE, dkelly@HiWAAY.net ======================================================================== Whom computers would destroy, they must first drive mad.
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