Re: Shutdown - 25 Years Later

Message-ID	<68057416@news.ausics.net> (permalink)
From	not@telling.you.invalid (Computer Nerd Kev)
Subject	Re: Shutdown - 25 Years Later
Newsgroups	comp.os.linux.misc
References	(3 earlier) <vtt1pr$2jm59$4@dont-email.me> <biOMP.2417830$t84d.626730@fx11.iad> <slrn10084b2.ort.jj@iridium.wf32df> <wwv5xizpaoe.fsf@LkoBDZeT.terraraq.uk> <vu2lpn$3mfun$1@dont-email.me>
Date	2025-04-21 08:24 +1000
Organization	Ausics - https://newsgroups.ausics.net

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Pancho <Pancho.Jones@protonmail.com> wrote:
> If they can do it for shutdown, presumably this is some method,
> some acknowledgement?

On shutdown the filesystems are remounted read-only, shown here
in dmesg (captured from serial port):

 EXT4-fs (sda3): re-mounted f109ff12-da03-4dfd-ad2a-cbd4eb713c43 ro. Quota mode: disabled.
 sd 0:0:0:0: [sda] Synchronizing SCSI cache
 reboot: Power off not available: System halted instead

"mount -o ro /deb/sda3" should do the first part during normal
operation too, but you'd need to have "/" on a ramdisk or tmpfs if
every physical filesystem is being mounted read-only.

I'm not so sure about "Synchronizing SCSI cache", is that like
running sync or something else (it didn't appear in dmesg when I
ran "sync" now)? A web search points to the "sg_sync" command
from sg3_utils as a way of triggering it manually:
https://manpages.debian.org/bookworm/sg3-utils/sg_sync.8.en.html

It sounds like they're talking about the cache in the drive itself,
making sure data is physically written out before power-off. Sounds
like a good idea. I wonder if there's a risk to unplugging
unmounted USB HDDs without doing that? Or does it only have a real
effect on actual SCSI drives (none present on the system where that
kernel message was captured)?

-- 
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#_ < |\| |< _#

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Shutdown - 25 Years Later Farley Flud <ff@linux.rocks> - 2025-04-16 14:32 +0000
  Re: Shutdown - 25 Years Later Eli the Bearded <*@eli.users.panix.com> - 2025-04-18 04:34 +0000
    Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-18 05:56 +0000
      Re: Shutdown - 25 Years Later Eli the Bearded <*@eli.users.panix.com> - 2025-04-18 06:38 +0000
        Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-18 08:15 +0000
    Re: Shutdown - 25 Years Later Andy Burns <usenet@andyburns.uk> - 2025-04-18 08:53 +0100
      Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-18 08:16 +0000
        Re: Shutdown - 25 Years Later Charlie Gibbs <cgibbs@kltpzyxm.invalid> - 2025-04-19 14:19 +0000
          Re: Shutdown - 25 Years Later Jim Jackson <jj@franjam.org.uk> - 2025-04-19 21:10 +0000
            Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-19 22:22 +0000
            Re: Shutdown - 25 Years Later Richard Kettlewell <invalid@invalid.invalid> - 2025-04-20 08:13 +0100
              Re: Shutdown - 25 Years Later The Natural Philosopher <tnp@invalid.invalid> - 2025-04-20 10:31 +0100
              Re: Shutdown - 25 Years Later Pancho <Pancho.Jones@protonmail.com> - 2025-04-20 12:28 +0100
                Re: Shutdown - 25 Years Later Richard Kettlewell <invalid@invalid.invalid> - 2025-04-20 20:44 +0100
                Re: Shutdown - 25 Years Later not@telling.you.invalid (Computer Nerd Kev) - 2025-04-21 08:24 +1000
                Re: Shutdown - 25 Years Later not@telling.you.invalid (Computer Nerd Kev) - 2025-04-21 08:28 +1000
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-21 00:29 +0000
                Re: Shutdown - 25 Years Later "Carlos E.R." <robin_listas@es.invalid> - 2025-04-22 10:35 +0200
                Re: Shutdown - 25 Years Later The Natural Philosopher <tnp@invalid.invalid> - 2025-04-22 10:03 +0100
                Re: Shutdown - 25 Years Later "Carlos E.R." <robin_listas@es.invalid> - 2025-04-22 11:27 +0200
                Re: Shutdown - 25 Years Later Pancho <Pancho.Jones@protonmail.com> - 2025-04-22 10:37 +0100
                Re: Shutdown - 25 Years Later The Natural Philosopher <tnp@invalid.invalid> - 2025-04-22 12:13 +0100
                Re: Shutdown - 25 Years Later Pancho <Pancho.Jones@protonmail.com> - 2025-04-22 12:38 +0100
                Re: Shutdown - 25 Years Later The Natural Philosopher <tnp@invalid.invalid> - 2025-04-22 14:29 +0100
                Re: Shutdown - 25 Years Later Pancho <Pancho.Jones@protonmail.com> - 2025-04-23 12:55 +0100
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-22 22:49 +0000
                Re: Shutdown - 25 Years Later candycanearter07 <candycanearter07@candycanearter07.nomail.afraid> - 2025-04-23 19:20 +0000
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-24 00:24 +0000
                Re: Shutdown - 25 Years Later candycanearter07 <candycanearter07@candycanearter07.nomail.afraid> - 2025-04-25 17:50 +0000
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-25 23:15 +0000
                Re: Shutdown - 25 Years Later John Ames <commodorejohn@gmail.com> - 2025-04-28 07:45 -0700
                Re: Shutdown - 25 Years Later Richard Kettlewell <invalid@invalid.invalid> - 2025-04-28 20:18 +0100
                Re: Shutdown - 25 Years Later The Natural Philosopher <tnp@invalid.invalid> - 2025-04-29 12:15 +0100
                Re: Shutdown - 25 Years Later Richard Kettlewell <invalid@invalid.invalid> - 2025-04-29 18:29 +0100
                Re: Shutdown - 25 Years Later The Natural Philosopher <tnp@invalid.invalid> - 2025-04-29 21:18 +0100
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-29 03:02 +0000
                Re: Shutdown - 25 Years Later Richard Kettlewell <invalid@invalid.invalid> - 2025-04-22 18:20 +0100
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-22 22:45 +0000
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-22 22:46 +0000
                Re: Shutdown - 25 Years Later The Natural Philosopher <tnp@invalid.invalid> - 2025-04-23 06:29 +0100
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-22 22:46 +0000
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-22 22:43 +0000
                Re: Shutdown - 25 Years Later "Carlos E.R." <robin_listas@es.invalid> - 2025-04-23 13:35 +0200
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-24 00:23 +0000
                Re: Shutdown - 25 Years Later "Carlos E.R." <robin_listas@es.invalid> - 2025-04-25 23:20 +0200
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-25 23:14 +0000
                Re: Shutdown - 25 Years Later The Natural Philosopher <tnp@invalid.invalid> - 2025-04-26 10:32 +0100
                Re: Shutdown - 25 Years Later Richard Kettlewell <invalid@invalid.invalid> - 2025-04-26 17:08 +0100
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-26 22:56 +0000
                Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-26 22:52 +0000
      Re: Shutdown - 25 Years Later The Natural Philosopher <tnp@invalid.invalid> - 2025-04-18 10:15 +0100
        Re: Shutdown - 25 Years Later Lawrence D'Oliveiro <ldo@nz.invalid> - 2025-04-19 00:06 +0000
  Re: Shutdown - 25 Years Later vallor <vallor@cultnix.org> - 2025-04-18 10:41 +0000
    Re: Shutdown - 25 Years Later % <pursent100@gmail.com> - 2025-04-18 06:17 -0700
    Re: Shutdown - 25 Years Later "Carlos E.R." <robin_listas@es.invalid> - 2025-04-18 15:29 +0200
  Re: Shutdown - 25 Years Later Farley Flud <ff@linux.rocks> - 2025-04-18 19:02 +0000

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