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Date:      Tue, 8 Dec 2009 14:13:39 -0500
From:      Maxim Khitrov <>
To:        Peter Steele <>
Cc:        "" <>
Subject:   Re: How do I create large partitions in FreeBSD?
Message-ID:  <>
In-Reply-To: <>
References:  <>

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On Tue, Dec 8, 2009 at 1:36 PM, Peter Steele <> wrote:
> We have 3U systems with 3Ware raid controllers configured to give us larg=
e 11TB logical drives. The diskinfo command shows this:
> # diskinfo -v da1
> da1
> =C2=A0 =C2=A0 =C2=A0 =C2=A0512 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
# sectorsize
> =C2=A0 =C2=A0 =C2=A0 =C2=A011999933104128 =C2=A0# mediasize in bytes (11T=
> =C2=A0 =C2=A0 =C2=A0 =C2=A023437369344 =C2=A0 =C2=A0 # mediasize in secto=
> =C2=A0 =C2=A0 =C2=A0 =C2=A01458908 =C2=A0 =C2=A0 =C2=A0 =C2=A0 # Cylinder=
s according to firmware.
> =C2=A0 =C2=A0 =C2=A0 =C2=A0255 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
# Heads according to firmware.
> =C2=A0 =C2=A0 =C2=A0 =C2=A063 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =
=C2=A0# Sectors according to firmware.
> =C2=A0 =C2=A0 =C2=A0 =C2=A0Y08210901E792700BAB9 =C2=A0 =C2=A0# Disk ident=
> We want to create a BSD slice to cover the entire drive. My plan was to u=
se the fdisk -I option:
> [snip]

You cannot use fdisk for this, because fdisk creates MBR partition
tables and these partitions are limited to 2 TB. You have three

1. Use GPT instead of MBR. This is handled by gpt (FreeBSD 7) and
gpart (FreeBSD 8) commands.
2. Use a "dangerously dedicated" partitioning scheme.
3. Bypass all partitioning issues and do what Polytropon suggested.

The third option will only work if you don't need to boot from the
array and are happy with a single 11TB file system.

The second option gives you partitions and the ability to boot
FreeBSD, but no other operating system will recognize the array.
Device names will be da1a, da1b, etc. To do this run the following

bsdlabel -w -B da1
bsdlabel -e da1
<edit your partitions>
newfs /dev/da1a
newfs -U /dev/da1d

I've never used GPT, but that's what you would have become familiar
with if you want these arrays to be recognized by operating systems
other than FreeBSD.

- Max

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