Date: Fri, 14 Nov 2008 13:52:41 +0200 From: Andrei Kolu <antik@bsd.ee> To: freebsd-fs@freebsd.org Subject: Re: Filesystem size and free space Message-ID: <491D6689.4090800@bsd.ee> In-Reply-To: <gfjmn2$7v7$1@ger.gmane.org> References: <491D5296.3000600@bsd.ee> <gfjmn2$7v7$1@ger.gmane.org>
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Ivan Voras wrote: > 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. > > So, I can say bye-bye to 50GB of space due to UFS filesystem features? IIRC then FreeBSD 4.x got 10% root reservation per filesystem and these days we got 1000 times bigger hard drives, do we need so much reservation (8% now I presume)? This filesystem would be read-only for users but writable to administrator to store large image files from other computers on network. If I understand correctly then this "reserved space" is used to avoid filesystem fragmentation. Can ZFS be more efficient, what if I create volumes per disk? Andrei
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