Date: Mon, 3 Jun 2002 21:14:46 -0700 From: "Drew Tomlinson" <drew@mykitchentable.net> To: "Bill Moran" <wmoran@potentialtech.com> Cc: <questions@freebsd.org> Subject: Re: Drive Space - Am I Getting All I Should? Message-ID: <005b01c20b7e$6873f590$1b01a8c0@TAGALONG> References: <003101c20b3e$13a0d320$0301a8c0@bigdaddy> <3CFC2D8C.5000906@potentialtech.com>
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----- Original Message ----- From: "Bill Moran" <wmoran@potentialtech.com> To: "Drew Tomlinson" <drew@mykitchentable.net> Cc: <questions@freebsd.org> Sent: Monday, June 03, 2002 8:01 PM Subject: Re: Drive Space - Am I Getting All I Should? > Drew Tomlinson wrote: > > I added a 80G IDE drive to my 4.5 machine. I used /stand/sysinstall > > to FDisk and Label the drive. Now after mounting, df -h shows: > > > > Filesystem Size Used Avail Capacity Mounted on > > /dev/ad0s1e 72G 1.0K 66G 0% /ftp > > > > dmesg shows the drive as 76319M so 72G seems reasonable: > > > > ad0: 76319MB <GENERIC GENERIC> [155061/16/63] at ata0-master UDMA33 > > > > The /stand/sysinstall disklabel editor sees it as the same size: > > > > Part Mount Size Newfs Part Mount Size > > Newfs > ----- ---- ----- ---- ----- ---- - > > ---- > > ad0s1e /ftp 76319MB UFS Y > > > > But the FDISK partition editor sees the drive geometry differently > > than dmesg: > > > > Disk name: ad0 FDISK Partition > > Editor > > DISK Geometry: 30629 cyls/81 heads/63 sectors = 156299787 sectors > > > > Offset Size End Name PType Desc Subtype > > Flags > > > > 0 156301488 156301487 ad0s1 3 freebsd 165 > > C> > > > > So how come df -h only shows 66G available? Where's the other 6G? Is > > this some limitation of FBSD or my system BIOS? > > If this isn't in the FAQ, it should be. It's in certain man pages. > The short answer is: Filesystem performance degrades very badly when > a filesystem is more than 92% full, so the OS reserves 8% of the drive > to keep performance reasonable. Only the root user can fill the disk > more than 92% > This is only a default value. You can change the reserved space on a > drive with either tunefs or with options when you newfs it. I don't > recommend it, though. The 8% thing was heavily researched and if you > fill a drive fuller than that, saving data to it is going to take > forever. Oh OK, duh. I knew that but 6G seemed so large that it didn't register in my head. After all, I had already lost 8G since it's supposed to be an 80G drive but FBSD only sees 72G. :) I don't know how it works but one never seems to get all the space that is advertised in a drive. I suspect it has something to do with total storage capacity vs. formatted storage capacity but that's a topic for another discussion. Thanks for pointing me back in the right direction. Thanks, Drew To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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