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Re: /etc/fstab question (problem)?



On 20/04/2023 04:03, David Christensen wrote:
* What if root attempts to remove everything under /etc, in anticipation of mounting a file system at /etc, when one or more programs have one or more open temporary files?

David, you were wrote /etc instead of /tmp in several messages, so at certain moment I thought that original issue was due to attempt to really mount another partition to /etc (e.g. for easier backups). Later an entry for /tmp was added to fstab on mounted partition, perhaps new version of fstab even propagated to initramfs. However after reboot there was no an entry for /etc in the /etc/fstab file residing on the root partition, so init had no change to mount /etc with another fstab (with the entry for /etc). It is literally bootstrap problem. Fortunately Default User posted complete fstab, so it was possible to rule out such hypothesis.

I used initramfs and initrd as synonyms because of file names /boot/initrd* and update-initramfs command. Even though /tmp entry should not be necessary during early init, I believe, it is safer to run "update-initrams -u" just to avoid surprise due to changes in fstab several days or weeks later when kernel update will arrive. It would be much harder to associate boot failure with fstab restored from backup instead of "broken" kernel package.

I am glad to read that the issue is solved, I see no problem with using of live image (it is wise to always have it available).

I think, in this case live image (unlike reboot) was not strictly necessary and may reduce down time if it is critical. I think, the following is safe enough (not verified, may contain typos or even errors):
- backup /etc/fstab and current initrd
- have a look into grub.cfg and grub manual to be able to boot using backup file
- restore /etc/fstab from backup
- Do not run "systemctl daemon-reload", since till shutdown systemd should work accordingly to content of old fstab version
- update-initramfs -u
- reboot. It is required after adding /tmp to fstab to make new fstab active and after update-initramfs to verify that new fstab does cause boot issue. Single reboot should be enough, however another one before update-initramfs is possible.
- mount --bind / /mnt
- remove files from /mnt/tmp/ remained from the previous boot. Otherwise some large file hidden by mounted /tmp may reduce free space available on the / partition
- umount /mnt
- remove initrd backup


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