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Date:      Tue, 4 Jun 2002 08:31:21 +0300 (EEST)
From:      Alexander V Zubchenko <stalker@hermes-comp.zp.ua>
To:        Drew Tomlinson <drew@mykitchentable.net>
Cc:        <questions@FreeBSD.ORG>
Subject:   Re: Drive Space - Am I Getting All I Should?
Message-ID:  <20020604082402.F32721-100000@server.hermes-comp.zp.ua>
In-Reply-To: <003101c20b3e$13a0d320$0301a8c0@bigdaddy>

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Hi!

On Mon, 3 Jun 2002, 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
Yes some space is preserved by filesystem, but, imho, there is also
other factor. Manufacturer of your drive may calculate 80G as
80'000'000'000 bytes. I'd calc with bc (with precision equal to 5 digits
after point) real capacity of the drive and get 74.5G.

> dmesg shows the drive as 76319M so 72G seems reasonable:
>
> ad0: 76319MB <GENERIC GENERIC> [155061/16/63] at ata0-master UDMA33
In PC BIOS disk may has maximum of 16 heads and 63 sectors per track.
It recalculate real geometry changing number of cylinders to get around.
And capacity of recalculated drive also may diffs from real value.

>
> 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
And this is your real drive geometry, imho.

Happy life for all,
Stalker.


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