From: Martin Steigerwald <Martin@lichtvoll.de>
To: util-linux@vger.kernel.org
Subject: Re: fdisk and 2048 sectors obsession.
Date: Tue, 28 Oct 2014 09:47:31 +0100 [thread overview]
Message-ID: <2236859.7Bm4QSfH9D@merkaba> (raw)
In-Reply-To: <544F0C88.1080807@gmail.com>
Hello you with the unknown real name,
Am Dienstag, 28. Oktober 2014, 08:54:56 schrieb dE:
> On 10/28/14 00:37, Felix Miata wrote:
> > dE composed on 2014-10-28 00:13 (UTC+0530):
> >> I was learning about GPT when I noticed this behavior of fdisk which I
> >> never though about before.
> >> Regardless of the partition table, fdisk always starts the first
> >> partition at 2048. In reality, the maximum size required by the gap
> >> between MBR and the 1st partition is a single sector, which's used by
> >> GRUB 1.5. GPT doesn't need this space at all.
> >> Then extended partitions too have a gap of 2048 sectors.
> >> Why this behavior?
> >
> > http://www.seagate.com/tech-insights/advanced-format-4k-sector-hard-drives
> > -master-ti/ may provide some insight WRT performance issues ensuing from
> > other start sector selections.
>
> But that works even with multiples of 8. So we can start from sector 8
> in MBR and 40 in GPT.
But then you have SoftRAID or Hardware RAID with 64 or 512 KiB chunk size. Or
you have SSD/PCIe or other flash with erase block sizes and so son. 1 MiB is
dividable by these usual sizes.
Why is this an issue for you?
Also see -c=dos switch or interactive "c" command:
merkaba:~> LANG=C fdisk /dev/sda
Welcome to fdisk (util-linux 2.25.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): c
DOS Compatibility flag is set (DEPRECATED!)
Command (m for help): o
"
Created a new DOS disklabel with disk identifier 0x7c1893d1.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1):
First sector (63-586072367, default 63):
"DOS-compatible mode is deprecated." is in red :)
Ciao,
--
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7
next prev parent reply other threads:[~2014-10-28 8:56 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-27 18:43 fdisk and 2048 sectors obsession dE
2014-10-27 19:07 ` Felix Miata
2014-10-28 3:24 ` dE
2014-10-28 3:55 ` Felix Miata
2014-10-28 4:30 ` dE
2014-10-28 5:53 ` Felix Miata
2014-10-28 7:32 ` Karel Zak
2014-10-28 7:49 ` Felix Miata
2014-10-28 8:48 ` Martin Steigerwald
2014-10-28 8:47 ` Martin Steigerwald [this message]
[not found] ` <544F3B20.7090109@gmail.com>
2014-10-28 14:33 ` dE
2014-10-28 17:11 ` Linda Walsh
2014-10-29 14:28 ` Dale R. Worley
2014-10-28 7:53 ` Karel Zak
2014-10-28 12:38 ` Martin K. Petersen
2014-10-28 14:53 ` dE
2014-10-28 15:35 ` Theodore Ts'o
2014-10-29 16:40 ` dE
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