[systemd-devel] Root remaining read-only after boot, no obvious reason why

[Dave Re]

Hi, Zbyszek,

The kernel default is to mount root ro, so unless there's some configuration to
mount or remount it rw, it'll stay ro. Generally this is configured in two
places 'rw' on the kernel command line and 'rw' in /etc/fstab. Do you have
one or both of those?
Yes. In this case, the kernel command line in grub contains the usual "ro" option, but /etc/fstab has an entry for root with "defaults" as the sole option. Default options are theoretically "rw, suid, dev, exec, auto, nouser, and async". To verify, I placed that option list in /etc/fstab for root, and saw the same behavior on reboot, so I eliminated the fstab entry as a potential issue.

Also related - the device is identified in fstab by UUID, not by label or partition. I verified the UUID of the device still matches the UUID in fstab, etc.

If I change the kernel command line in grub to use "rw", root mounts rw as expected.

If a remount is done, it'll be done by systemd-remount-fs.service. Do you
see it in the logs?
Ah, I misunderstood initrd-switch-root - thanks. On a system that successfully boots with root mounted rw, I don't see anything about systemd-remount-fs.service until it's shutdown, when the service is stopped, but systemd was ratelimited by the kernel on that boot, so a startup message may have been missed. But - I can see that systemd-remount-fs.service is Active/exited (via systemctl status command).

On the problem system, systemd-remount-fs.service is inactive/dead - and shows the same status if I reboot with "rw" on the kernel command line (which would be expected, given our symptoms, I think?).

On both systems, it's linked in /usr/lib/systemd/system/local-fs.target.wants - so, should be run as part of getting to that target, if I understand correctly? What should my next step be to determine why it's not being run?

Thank you!

Dave








Dave Re
Manager, DevOps Engineering
www.imprivata.com
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​480 Totten Pond Road
​Waltham, MA  02451
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