From owner-freebsd-questions Mon Jun 3 19:55:55 2002 Delivered-To: freebsd-questions@freebsd.org Received: from infinity.aesredfish.net (ns1.aesredfish.net [65.168.0.12]) by hub.freebsd.org (Postfix) with ESMTP id 4BF9537B407 for ; Mon, 3 Jun 2002 19:55:49 -0700 (PDT) Received: from potentialtech.com (mhope-dhcp-65-168-1-181.dashfast.com [65.168.1.181]) by infinity.aesredfish.net (8.11.6/8.11.0) with ESMTP id g542tjU24698; Mon, 3 Jun 2002 22:55:45 -0400 Message-ID: <3CFC2D8C.5000906@potentialtech.com> Date: Mon, 03 Jun 2002 23:01:32 -0400 From: Bill Moran User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.0rc1) Gecko/20020502 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Drew Tomlinson Cc: questions@freebsd.org Subject: Re: Drive Space - Am I Getting All I Should? References: <003101c20b3e$13a0d320$0301a8c0@bigdaddy> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG 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 [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. -- Bill Moran Potential Technology http://www.potentialtech.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message