Testing ext4 and auto fix

[Keith]

On 12/6/23 1:13 PM, Jerry Geis wrote:
> 
> 
> On Wed, Dec 6, 2023 at 1:54 PM Jose Luis Alarcon Sanchez 
> <jlalarcon at planetmail.net <mailto:jlalarcon at planetmail.net>> wrote:
> 
>     On dic. 6 2023, at 7:06 pm, Jerry Geis <jerry.geis at gmail.com
>     <mailto:jerry.geis at gmail.com>> wrote:
> 
>      > How do I enable "auto fix" no matter what on ext4 ?
>      > Then how do I simulate that ?
>      >
>      >
>      > I just tried doing on 22.04:
>      > touch  /forcefsck
>      > shutdown -r now
>      >
>      > I did not see any file system check,
>      > when I log back in the file is still present.
>      >
>      > When power goes out on my remote computer - I want it to come back up
>      > no matter what.
>      >
>      > Thanks,
>      >
>      > Jerry
>      >
> 
>     Hi Jerry.
> 
>     Isn´t with a dot in the instruction?. something like:
>     touch  /.forcefsck
> 
>     Try it. Nothing to loose.
> 
>     Regards.
>     Jose Luis.
> 
>     --
>     https://lordofunix.org/ <https://lordofunix.org/>
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> 
> Seems I had a typo on such a simple command. :)
> I created /forcefsck   (not /forcefsk)
> I rebooted and the file is gone. OK.
> 
> How then to just go ahead "fix" any issue. This is on a remote computer 
> - and just need it to "fix" and boot.
> I did find /fsckoptions  and I could put a -y in there - but how do I 
> "simulate" a file system issue - so the fix will happen ?
> 

Well you could always create a real issue with relatively minimal damage 
to the filesystem if you want a real world test.

Log out of graphical environment and switch to a virtual terminal
Take system to runlevel 1 aka rescue mode

$ sudo telinit 1

force reboot without unmounting drives and not going through any proper 
shutdown basically as if a brief power loss occurred.

# echo b > /proc/sysrq-trigger

When system is rebooted, check as root /run/initramfs/fsck.log
to see what fsck fixed. On my system, this resulted:
Log of fsck -C -a -V -t ext4 /dev/sda3
Wed Dec  6 21:39:32 2023

fsck from util-linux 2.37.2
[/usr/sbin/fsck.ext4 (1) -- /dev/sda3] fsck.ext4 -a -C0 /dev/sda3
/dev/sda3: recovering journal
/dev/sda3: clean


Normally, you don't need to force a fs check since the systemd-fsck-root 
service will automatically detect whether it needs to run fsck on the 
root filesystem on every boot and will initiate a safe repair if it 
needs to.

To manually force a check, put fsck.mode=force in the kernel 
command-line. Use fsck.repair=yes (default is "preen") to initiate 
repairs that could potentially worsen a damaged filesystem.

Using tune2fs, you could also change the max-mount-count to 1 (assuming 
the actual mount count is +1) which will force a fs check on every boot 
until the max count is set to another number (0 or -1 to disable)

-- 
Keith