Re: Converted EXT4 is Slow to Check

From	"Carlos E.R." <robin_listas@es.invalid>
Newsgroups	comp.os.linux.misc
Subject	Re: Converted EXT4 is Slow to Check
Date	2026-05-06 13:36 +0200
Message-ID	<5nlrcmxkk3.ln2@Telcontar.valinor> (permalink)
References	(10 earlier) <10tbc82$1nih$8@dont-email.me> <34socmxtjb.ln2@Telcontar.valinor> <10tdp1u$oc5h$4@dont-email.me> <kbfqcmxc22.ln2@Telcontar.valinor> <wwvtssknbaj.fsf@LkoBDZeT.terraraq.uk>

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On 2026-05-06 11:21, Richard Kettlewell wrote:
> "Carlos E.R." <robin_listas@es.invalid> writes:
>> On 2026-05-05 23:56, Lawrence D’Oliveiro wrote:
>>> On Tue, 5 May 2026 12:07:31 +0200, Carlos E.R. wrote:
>>>> On 2026-05-05 02:05, Lawrence D’Oliveiro wrote:
>>>>> On Mon, 4 May 2026 20:04:04 +0200, Carlos E.R. wrote:
>>>>>> Why XFS makes it worse
>>>>>>
>>>>>> XFS does not support embedding GRUB core files inside the
>>>>>> filesystem itself (unlike something like ext4 with certain GRUB
>>>>>> setups). So GRUB has fewer fallback options.
> 
> “Embedding” is a confusing word to use here, since Grub uses it to refer
> to storing diskboot.img+core.img in the embedding area, i.e. after the
> MBR but before the first partition.
> 
>>>>> That statement doesn’t make any sense. There is no “embedding GRUB
>>>>> core files inside the filesystem itself”. Those “GRUB core files”
>>>>> are not “embedded” in the filesystem in any special way, they are
>>>>> just files like any other files, copied as necessary by the
>>>>> bootloader installation system to put the necessary stuff into the
>>>>> actual boot partition. Which is has its own layout, independent of
>>>>> any filesystem volume format, and nothing to do with any filesystem
>>>>> volume format.
>>>>
>>>> No. Grub 2 writes code directly to the start of the partition. This
>>>> is known.
>>>
>>> There is no “start of the partition”. There is an *entire* “boot
>>> partition” devoted to this purpose. This is entirely separate from any
>>> regular filesystem partition, whether ext4, XFS or whatever.
> 
> Carlos is correct that (in certain configurations) some code is written
> to the start of the boot partition. However:
> 
>> Man, focus. I am talking of the case when grub is installed in the "/"
>> partition, instead of in the MBR. Sector zero has grub part 1. Then
>> goes grub 1.5 to the initial sectors.s
>>
>> If you do not understand this, I suggest you study. I am out.
> 
> There is no such thing as a ‘stage 1.5’ in Grub 2. As best I can tell
> from studying the documentation, the only code written into the boot
> partition (if any) is the single-sector diskboot.img. In such a
> configuration, core.img is an ordinary file, as Lawrence says.

<https://www.google.com/search?client=firefox-b-e&channel=entpr&q=grub+stage+1.5>

AI Overview

GRUB Stage 1.5 is an intermediate bootloader stage in GRUB Legacy (0.9x) 
that acts as a bridge between the MBR-based Stage 1 and 
file-system-aware Stage 2. It resides in the 30 KB gap immediately 
following the Master Boot Record (MBR). Its primary purpose is to 
provide filesystem drivers (e.g., ext2, XFS) allowing Stage 1 to load 
Stage 2 from a file system.
This video explains the Linux boot process and the role of GRUB:

Function: Stage 1.5 allows GRUB to load files from a filesystem, which 
the very small Stage 1 cannot do.

Location: Usually embedded in the unused sectors after the MBR and 
before the first partition, or sometimes within the boot loader area of 
specific filesystems.

Version Note: Stage 1.5 is specific to GRUB Legacy. In GRUB 2, this was 
replaced by core.img.



Ok, confusion in the naming.


> 
> 
> AFAICT the way it works on an MBR system is:
> 
> 1) boot.img is always in the MBR, with the disk address of diskboot.img
>     copied into it. It contains enough code to load diskboot.img and run
>     it.
> 
> 2) diskboot.img can be anywhere, and contains the list of disk addresses
>     for core.img plus enough code to load core.img (using that list) and
>     run it.
> 
> 3) core.img contains all the code for reading filesystems natively,
>     interacting with the user, loading a kernel etc. No more blocklists
>     are necessary at this point.
> 
> This is realized in two documented configurations:
> 
> 1) boot.img in the MBR, diskboot.img+core.img the embedding area
>     i.e. after the MBR but before the first partition.
> 
> 2) boot.img in the MBR, diskboot.img in the first sector of a partition
>     containing a real filesystem, and core.img as an ordinary file in
>     that filesystem.
> 
>     This is not particularly well documented but it depends on the
>     filesystem reserving the first sector for use by boot loaders. This
>     This appears to correspond to the reserved_first_sector flag in the
>     implementation, which is zero for Grub’s XFS implementation,
>     consistent with XFS not being usable in this mode of operation.
> 
> See
> https://www.gnu.org/software/grub/manual/grub/grub.html#BIOS-installation
> for the documentation.
> 
> Fortunately none of this nonsense is necessary on modern platforms.
> 


Yep :-)

-- 
Cheers, Carlos.
ES🇪🇸, EU🇪🇺;

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Thread

Converted EXT4 is Slow to Check Leroy H <lh@somewhere.net> - 2026-04-24 00:04 +0000
  Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-04-24 02:29 +0000
    Re: Converted EXT4 is Slow to Check Leroy H <lh@somewhere.net> - 2026-04-24 09:23 +0000
      Re: Converted EXT4 is Slow to Check The Natural Philosopher <tnp@invalid.invalid> - 2026-04-24 10:28 +0100
      Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-04-24 19:46 -0400
  Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-04-24 10:55 +0200
  Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-04-26 12:53 +0000
    Re: Converted EXT4 is Slow to Check Leroy H <lh@somewhere.net> - 2026-04-26 14:01 +0000
      Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-04-26 20:54 +0200
      Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-04-27 13:25 +0000
  Re: Converted EXT4 is Slow to Check Rich <rich@example.invalid> - 2026-04-27 15:24 +0000
    Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-04-29 13:10 +0000
      Re: Converted EXT4 is Slow to Check Rich <rich@example.invalid> - 2026-04-29 15:57 +0000
        Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-04-30 01:02 -0400
          Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-04-30 11:01 +0200
          Re: Converted EXT4 is Slow to Check Borax Man <rotflol2@hotmail.com> - 2026-04-30 12:36 +0000
            Re: Converted EXT4 is Slow to Check gazelle@shell.xmission.com (Kenny McCormack) - 2026-04-30 14:32 +0000
              Re: Converted EXT4 is Slow to Check Nuno Silva <nunojsilva@invalid.invalid> - 2026-04-30 16:42 +0100
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-03 12:29 +0000
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-03 21:13 +0200
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-03 22:05 +0000
                Re: Converted EXT4 is Slow to Check jayjwa <jayjwa@atr2.ath.cx.invalid> - 2026-05-04 12:08 -0400
                Re: Converted EXT4 is Slow to Check John Bokma <contact@johnbokma.com> - 2026-05-04 19:24 +0200
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-05 00:00 +0000
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-04 12:41 +0000
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-04 20:04 +0200
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-05 00:05 +0000
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-05 12:07 +0200
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-05 21:56 +0000
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-06 02:41 +0200
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-06 04:13 +0000
                Re: Converted EXT4 is Slow to Check Nuno Silva <nunojsilva@invalid.invalid> - 2026-05-06 13:03 +0100
                Re: Converted EXT4 is Slow to Check Richard Kettlewell <invalid@invalid.invalid> - 2026-05-06 10:21 +0100
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-06 13:36 +0200
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-06 21:16 +0000
                Re: Converted EXT4 is Slow to Check Nuno Silva <nunojsilva@invalid.invalid> - 2026-05-06 23:31 +0100
                Re: Converted EXT4 is Slow to Check Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-05-07 06:41 +0200
                Re: Converted EXT4 is Slow to Check Nuno Silva <nunojsilva@invalid.invalid> - 2026-05-07 08:34 +0100
                Re: Converted EXT4 is Slow to Check Richard Kettlewell <invalid@invalid.invalid> - 2026-05-07 09:06 +0100
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-07 10:58 +0200
                Re: Converted EXT4 is Slow to Check not@telling.you.invalid (Computer Nerd Kev) - 2026-05-08 09:00 +1000
                Re: Converted EXT4 is Slow to Check Nuno Silva <nunojsilva@invalid.invalid> - 2026-05-08 09:45 +0100
                Re: Converted EXT4 is Slow to Check not@telling.you.invalid (Computer Nerd Kev) - 2026-05-09 10:01 +1000
                Re: Converted EXT4 is Slow to Check Leroy H <lh@somewhere.net> - 2026-05-09 00:12 +0000
                Re: Converted EXT4 is Slow to Check Computer Nerd Kev <not@telling.you.invalid> - 2026-05-09 17:30 +1000
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-08 00:12 +0000
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-08 10:57 +0200
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-08 09:26 +0000
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-08 12:47 +0200
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-08 21:55 +0000
                Re: Converted EXT4 is Slow to Check Nuno Silva <nunojsilva@invalid.invalid> - 2026-05-08 16:42 +0100
                Re: Converted EXT4 is Slow to Check Richard Kettlewell <invalid@invalid.invalid> - 2026-05-08 22:42 +0100
                Re: Converted EXT4 is Slow to Check Nuno Silva <nunojsilva@invalid.invalid> - 2026-05-09 08:34 +0100
                Re: Converted EXT4 is Slow to Check Richard Kettlewell <invalid@invalid.invalid> - 2026-05-09 10:18 +0100
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-09 13:31 +0200
                Re: Converted EXT4 is Slow to Check Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-05-09 09:57 +0200
                Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-05-06 00:53 -0400
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-06 10:47 +0200
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-07 13:17 +0000
                Re: Converted EXT4 is Slow to Check rbowman <bowman@montana.com> - 2026-05-05 01:22 +0000
                Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-05-05 00:52 -0400
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-05 12:11 +0200
                Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-05-06 00:46 -0400
                Re: Converted EXT4 is Slow to Check rbowman <bowman@montana.com> - 2026-05-06 06:43 +0000
                Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-05-06 11:05 -0400
                Re: Converted EXT4 is Slow to Check rbowman <bowman@montana.com> - 2026-05-06 19:47 +0000
                Re: Converted EXT4 is Slow to Check Bobbie Sellers <bliss-sf4ever@dslextreme.com> - 2026-05-06 15:10 -0700
                Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-05-06 22:04 -0400
                Re: Converted EXT4 is Slow to Check rbowman <bowman@montana.com> - 2026-05-07 06:32 +0000
                Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-05-07 17:37 -0400
                Re: Converted EXT4 is Slow to Check rbowman <bowman@montana.com> - 2026-05-08 00:30 +0000
                Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-05-07 23:20 -0400
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-06 10:51 +0200
                Re: Converted EXT4 is Slow to Check The Natural Philosopher <tnp@invalid.invalid> - 2026-05-06 17:38 +0100
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-06 20:52 +0200
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-07 13:14 +0000
                Re: Converted EXT4 is Slow to Check The Natural Philosopher <tnp@invalid.invalid> - 2026-05-07 16:51 +0100
                Re: Converted EXT4 is Slow to Check Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2026-05-07 18:35 +0000
                Re: Converted EXT4 is Slow to Check The Natural Philosopher <tnp@invalid.invalid> - 2026-05-07 20:08 +0100
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-08 12:47 +0000
                Re: Converted EXT4 is Slow to Check The Natural Philosopher <tnp@invalid.invalid> - 2026-05-08 14:22 +0100
                Re: Converted EXT4 is Slow to Check Rich <rich@example.invalid> - 2026-05-08 13:24 +0000
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-09 14:08 +0000
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-07 20:20 +0200
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-08 12:40 +0000
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-08 00:17 +0000
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-08 12:38 +0000
                Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-08 21:07 +0000
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-09 14:06 +0000
                Re: Converted EXT4 is Slow to Check Rich <rich@example.invalid> - 2026-05-09 15:27 +0000
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-10 12:28 +0000
                Re: Converted EXT4 is Slow to Check "Carlos E.R." <robin_listas@es.invalid> - 2026-05-05 12:08 +0200
              Re: Converted EXT4 is Slow to Check The Natural Philosopher <tnp@invalid.invalid> - 2026-04-30 17:05 +0100
                Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-04-30 14:28 -0400
              Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-03 12:15 +0000
            Re: Converted EXT4 is Slow to Check The Natural Philosopher <tnp@invalid.invalid> - 2026-04-30 16:54 +0100
            Re: Converted EXT4 is Slow to Check Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-05-01 00:15 +0000
              Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-04-30 20:36 -0400
                Re: Converted EXT4 is Slow to Check Borax Man <boraxman@geidiprime.invalid> - 2026-05-03 12:08 +0000
      Re: Converted EXT4 is Slow to Check c186282 <c186282@nnada.net> - 2026-04-30 00:59 -0400

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