Date: Sat, 2 Mar 2002 10:15:32 -0500 From: "C J Michaels" <cjm2@earthling.net> To: "David Smithson" <david@customfilmeffects.com> Cc: <freebsd-questions@freebsd.org> Subject: RE: defragment UFS Message-ID: <CDEJIONOMGKHCNHBALKPGEKJCAAA.cjm2@earthling.net> In-Reply-To: <3C807A58.1030209@customfilmeffects.com>
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> -----Original Message----- > From: owner-freebsd-questions@FreeBSD.ORG > [mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of David Smithson > Sent: Saturday, March 02, 2002 2:08 AM > Cc: freebsd-questions@FreeBSD.ORG > Subject: Re: defragment UFS > > > I see. Well that's dandy. I have another filesystem-related question. > I have a 1.2TB file server running FreeBSD. The filesystem is exported > via SMB. When I view the properties of a SAMBA shared folder, there are > two file sizes shown: "size" and "size on disk". The "size on disk" is > consitently greater than the "size". I ignorantly assumed this meant > that data was fragmented. Do you have any idea what this means? When Windows is reporting size vs size on disk, it's reporting the difference between the actual size of the files and the amount of space allocated to the file. There's a minimum amount of space that can be allocated on a FAT filesystem (which depends on several factors). E.g. if the cluster size is 32KB, and you save a file that's only 8KB, it still takes up 32KB "on disk". This is generally called "slack" space. Couple this with the high fragmentation rate of FAT/NTFS filesystems and you end up with alot of space being allocated to files that isn't actually used. What you are seeing in the properties box when viewing a SAMBA share is pure fiction. Your 2k box believes it is looking at an NTFS filesystem (not ufs) so it also assumes the same cluster size, and the same issues with slack space. Long story short, the actual size should be accurate, and the "size on disk" is fiction, just ignore it. > > The question of data size came about when I ran a backup of a directory > tree that is reportedly 76 GB. The Large DTF tape medium I'm using is > supposed to hold 108 GB at it's only compression ratio of 1:2.59. I ran > "tar -cvf /dev/sa0 /dir-tree". After some time, tar reported that it > had reached the end of the medium. Clearly 76 GB should fit on this > tape. I can't figure out what is happening here. Any ideas? > > Thanks for your help. > > > Cliff Sarginson wrote: > > >On Fri, Mar 01, 2002 at 08:57:16PM -0800, David Smithson wrote: > > > >>Hi all. Is there a defragment utility for FreeBSD? Is it even > necessary? If not, why not? > >> > >No. > >No. > >No matter what size file you have on FreeBSD it will never have more > >than one partially filled block, when a file grows it fills the spaces > >up rather than allocating new blocks uneccesarily a la DOS. -- Chris "To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public." --Theodore Roosevelt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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