Date: Wed, 30 Jul 2014 14:07:45 +0100 From: Matthew Seaman <matthew@freebsd.org> To: freebsd-questions@freebsd.org Subject: Re: huge difference between du and df - no open file descriptors Message-ID: <53D8EE21.8020109@freebsd.org> In-Reply-To: <20140730142609.1ac2bdc9@azubix.tec.work> References: <20140730142609.1ac2bdc9@azubix.tec.work>
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This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --JQSonEARSFqKmJcDblCs0M72nGUCLa7GU Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 07/30/14 13:26, Nils Effenberger wrote: > du and df are showing signifcantly different values on our storage > system: >=20 > [root@zhoernchen ~]# df -h / > Filesystem Size Used Avail Capacity Mounted on =20 > /dev/mirror/root 4.8G 4.1G 336M 93% /=20 > [root@zhoernchen ~]# du -shx /=20 > 2.3G / >=20 > root@zhoernchen:~ # gpart show=20 > =3D> 34 97696301 ada0 GPT (47G) > 34 128 1 freebsd-boot (64K) > 162 10485760 2 freebsd-ufs (5.0G) > 10485922 10485760 3 freebsd-zfs (5.0G) > 20971682 76724653 4 freebsd-zfs (37G) >=20 > =3D> 34 97696301 ada1 GPT (47G) > 34 128 1 freebsd-boot (64K) > 162 10485760 2 freebsd-ufs (5.0G) > 10485922 10485760 3 freebsd-zfs (5.0G) > 20971682 76724653 4 freebsd-zfs (37G) >=20 > (The zfs partitions are zil and l2arc of the zpool on HDDs) >=20 > My first thought was that this was due to open file descriptors but I > could'nt find anything relevant with fstat. > To be absolutely shure I rebooted (fortunately the system isn't > productive yet) but that didn't help either. >=20 > To enshure that I was using fstat correctly (I'm not that familiar with= > FreeBSD) I created a file of ~350MB, opened it with less, deleted it > while opened, was able to find it with fstat, closed less and found the= > system in following state: >=20 > root@zhoernchen:~ # du -shx / > 2.2G / > root@zhoernchen:~ # df -h / > Filesystem Size Used Avail Capacity Mounted on > /dev/mirror/root 4.8G 4.5G -13M 100% / >=20 > Could someone explain this and how I get that fixed? One other way of using up space in a partition without it showing up in du(1) is to have files hidden underneath the mount points for other filesystems. So you've got a 5GB UFS partition and a ZFS pool somewhere -- if you have (say) a file /mnt/big-file on the root and then you mount another filesystem (eg. ZFS) on top of /mnt you'll hide that file from du(1), but it will still be using space on the root partition and show up in df(1) output. The only way to find this sort of thing is to unmount those other filesystems and look at what exists under the mount point. You can also use up space invisibly by creating snapshots -- see mksnap_ffs(8) and snapinfo(8). Cheers, Matthew --JQSonEARSFqKmJcDblCs0M72nGUCLa7GU Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQJ8BAEBCgBmBQJT2O4oXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXQxOUYxNTRFQ0JGMTEyRTUwNTQ0RTNGMzAw MDUxM0YxMEUwQTlFNEU3AAoJEABRPxDgqeTn1L0P/AgQWdrThTQJt+Go/vjUqizf 1bFdbiRjnSYvs0Zje/nlOSSCg8jljMH67comY09iD+uopuAENpx5bD7PtYe1bfEa hEJ1aqAlf0ceYHSMA5SEjKHAeDlqBGQEieGDCVD1zV6nhSLEe3xoxyJDxg5AX9l3 258lsOjt3liaWJl+Z1SsjxbWhe/6H7aCYRBMh4pwxSm0d4R1jpzB2uk86n08Dtef AJXvd9Z1LLqNsrOQ31NTkWbIpmQAuA9fXuZ7XCA7Sg5IxuQbCk2OXEYTHyj9zRDn 991xc6tPjRp6UiEkimhWXtiroOANj8D5sIQve5MWHED7kpOh858GpvBH5E+Gf6c5 a5++Zfdlo3urz392n4nufSSwz7WZ9WNMtYOovk3hYj9JdcMABbDnukmoU3bnwlrp I8Wl0ENgyVt55oFbhrjJnaj1Kucf8HeMX47358HU6dHT1ZZhHMLf0fGLm2C60OQH RvGuLPWsBkdnYlzcnylovAD34eqIU1F2VGKzNeN1RoGLBd35pZX3IcMJH95hgjNc Y1rVave5T2uAu+KoB0Xg7XhUAc95pyjJBk0RhZRF6IcZ4JFjvkqOnSPC2ZLW0sFA 9QNXskDPwKSJSYTvkSkyP66Y2cCNDgjt8GpSBDHn9E6QnUZgacdypzLk6YzySJfL WF0nZ6EjySM7FR481lOX =aBcp -----END PGP SIGNATURE----- --JQSonEARSFqKmJcDblCs0M72nGUCLa7GU--
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