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	2026-05-04 20:04 +0200
Message-ID	<kl3ncmxfq4.ln2@Telcontar.valinor> (permalink)
References	(4 earlier) <10svp5o$3ler1$1@news.xmission.com> <10svt92$p5k9$2@dont-email.me> <slrn10veft7.1akm.boraxman@geidiprime.invalid> <fcjkcmxt1h.ln2@Telcontar.valinor> <slrn10vh4vv.2tn.boraxman@geidiprime.invalid>

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On 2026-05-04 14:41, Borax Man wrote:
> On 2026-05-03, Carlos E.R. <robin_listas@es.invalid> wrote:
>> On 2026-05-03 14:29, Borax Man wrote:
>>> Come to think of it, its quite late in the game to be still running
>>> EXT3!  EXT4 is already nearly two decades old.  Personally, I'd
>>> recommend BTRFS or XFS, especially for large storage/archival.
>>
>> I don't trust btrfs, and xfs poses problems when used for root; for data
>> it is perfect.
>>
>> I have a raid 6 with 8 active disks, LUKS encrypted and using btrfs with
>> compression. It has developed an error, impossible to correct (I don't
>> know how, got advice about what to do, but took days and it aborted.
>> Eventually will redo with XFS instead).
>>
> 
> What issues are there with XFS for root?

I don't remember well, and I feel lazy about writing it up, so I asked 
chatgpt.

The core problem

On BIOS systems (not UEFI), GRUB traditionally embeds part of its code 
(“core.img”) in the post-MBR gap—the space between the MBR and the first 
partition.

This works fine if that gap exists (common with older partition layouts).
But modern partitioning tools or certain layouts don’t leave enough 
space there.

Now add XFS:

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.

That leads to this situation:

If there’s no post-MBR gap available
And your /boot is on XFS
→ GRUB has nowhere safe to put core.img
Resulting error

You’ll often see something like:

embedding is not possible, but this is required for cross-disk install
The usual fixes
1. Use a BIOS boot partition (recommended for GPT + BIOS)

Create a small (~1–2 MB) partition with type:

bios_grub (GPT flag)

GRUB will store its core image there safely.

2. Use a different filesystem for /boot

Instead of XFS:

ext4 is the most common safe choice
3. Switch to UEFI (if possible)

With UEFI:

GRUB lives in the EFI System Partition (FAT32)
No need for embedding tricks at all

> 
> I have had an issue with BTRFS in the past, an error which couldn't be
> corrected.  The error didn't have any impact except failing to read one
> extended attribute from a file, which didn't matter that much, but it
> did mean that one subvolume couldn't be sent properly (a fact I became
> aware of too late).  The filesystem seemed to work fine regardless.
> What made me lost a little trust is I backed up then ran FSCK, and FSCK
> made a complete dogs breakfast of the filesystem.  This might have been
> in 2015, thereabouts.

Well, I hit "something" less than a year ago.

> 
> But that was over 10 years ago, and its been fine ever sense.  As I
> mentioned before, the checksumming picked up issues that would have
> otherwise gone unnoticed and led to lost data, so I do trust it but
> still, I'd only use it if I really needed the features.  If not, XFS

-- 
Cheers, Carlos.
ES🇪🇸, EU🇪🇺;

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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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