Gentoo Archives: gentoo-user

From: Grant <emailgrant@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Re: Gentoo on a Dell XPS 13 Ultrabook
Date: Sun, 04 Mar 2012 22:37:27
Message-Id: CAN0CFw3-FNJC30GVWppmFn24gjAc4BGYKUJ_Uq-iAwfOxBS0aw@mail.gmail.com
In Reply to: Re: [gentoo-user] Re: Gentoo on a Dell XPS 13 Ultrabook by Alan McKinnon
1 >> >> [snip]
2 >> >>>> 1. fdisk won't let me specify a start block before 2048 even
3 >> >>>> though I deleted all partitions.
4 >> >>>>
5 >> >>>
6 >> >>> That's normal. It's a long story, but Windows Vista and Windows 7
7 >> >>> expects the first partition to start at sector 2048.
8 >> >>>
9 >> >>> You can force a lower number by toggling "DOS compatibility";
10 >> >>> this should let you start the first partition as low as sector 63.
11 >> >>>
12 >> >>> HOWEVER, make sure that all partitions begin at multiples of 8
13 >> >>> (e.g., 64, 72, 80, and so on); this will save you a lot of grief
14 >> >>> if it happens that the hard disk you're using has 4KiB-sectors.
15 >> >>
16 >> >> I just looked up the start block for my other systems and they're
17 >> >> all on 63.  Is performance impacted on all of these systems since
18 >> >> they aren't started on 64?
19 >> >>
20 >> >> - Grant
21 >> >>
22 >> >
23 >> > The performance is only impacted if the sector size is something
24 >> > other than 512 bytes. The newer 4K sector size used by some higher
25 >> > density drives requires that you start partitions on a sector
26 >> > boundary or they will perform badly. There isn't an actually
27 >> > performance need to actually start on 2048 but the fdisk-type
28 >> > developer folks are doing that to be more compatible with newer
29 >> > Windows installations.
30 >>
31 >> All my drives says this from fdisk:
32 >>
33 >> Units = sectors of 1 * 512 = 512 bytes
34 >> Sector size (logical/physical): 512 bytes / 512 bytes
35 >> I/O size (minimum/optimal): 512 bytes / 512 bytes
36 >>
37 >> So it doesn't matter where the first partition starts?
38 >
39 > Correct. Those drives are all the same style as you've
40 > been using for years. If partitions start at 63, that's just an msdos
41 > convention. For reasons I've never understood, Windows liked to reserve
42 > the first 32k for some purpose or other.
43
44 So fdisk used to enforce a block 63 start point and now it enforces a
45 2048 start point? fdisk is the one doing this?
46
47 - Grant

Replies

Subject Author
Re: [gentoo-user] Re: Gentoo on a Dell XPS 13 Ultrabook Pandu Poluan <pandu@××××××.info>