Filesystem size and free space

[Ivan Voras]

Andrei Kolu wrote:
> Hi,
> 
> due to migration from Windows Server 2003 NTFS filesystem to FreeBSD
> 7.1Beta2 UFS+softupdates filesystem I encountered strange problem. NTFS
> formatted filesystem seen in FreeBSD as read-only and exactly 500GB with
> 28GB free space but after format to UFS disk shows up as 484GB and after
> copying back files that was on same disk (from ntfs) UFS filesystem
> shows that I got -33GB (minus?) of free space. What's wrong? Is UFS so
> inefficient filesystem or it is a bug?

UFS reserves a small percentage of the space for the superuser (root)
utilities and also for performance benefits. "-33 GB" is telling you
that you have used 33 GB of this reserved space, which isn't good if the
file system is going to be used in a read-write environment. If the file
system is going to be used read-only, you can safely ignore this;
otherwise try never to use the reserved space. In particular, userland
programs running under non-root user accounts will not see this reserved
space and will get "out of disk space" errors when they try to add data
to files in such a file system.

You can lower the size of this reserved space with "tunefs -m" which
will allow non-root users to access more space, but this isn't
recommended. Either delete files or buy a bigger drive.

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