Hi Olav, Am 15.08.20 um 08:43 Uhr schrieb seroton10@gmail.com:
Hi,
When installing openSUSE (any flavour), the installer offers a choice between the "server" and "transactional server" roles, among others.
If I choose to install using the "server" role, is there a (supported) procedure by which I can later convert it into a "transactional server"? (Assume using btrfs for /, and having snapshots.)
No, this is unsupported - see Richards mail for the differences between the roles.
I tried to do this conversion on a test system running openSUSE Leap 15.2 as follows:
* run "zypper install patterns-base-transactional_base" * edit /etc/fstab to make root read-only * reboot
This appears to work: The system self-updates, and reboots when needed; /etc has been turned into an overlay filesystem; and zypper up tells me to use the transactional-update tool.
However, one of the packages installed during the conversion is "read- only-root-fs", and its description contains a rather stern warning:
Files, scripts and directories to run the system with a read-only root filesystem with /etc writeable via overlayfs.
This package should never be installed in an already running system! It should only be selected by a system role for a read-only root filesystem with transactional updates. The package will create / modify entries for mounting /etc and /var. Those entries are used by dracut to mount the overlay file systems during the early boot phase.
After reading this, I ask myself, was it just dumb luck that the test system wasn't destroyed during the conversion? What can/does go wrong if read-only-root-fs is installed in an already running system, against the advice given?
Any clarification on this would be much appreciated.
I was also quite surprised to see this approach working - I would have
expected that at least the /etc overlays would be falling apart.
So I just checked the read-only-root-fs spec file. The necessary
directories will be created there even on an existing system, so you may
indeed have created a working setup ;-)
HOWEVER: The warning is imho completely legitimate. Installing this
package will not magically convert an existing read-write system into a
read-only system, but will require manual interaction. In fact you
missed one important step: The root subvolume should also be set
read-only (i.e. not only setting the read-only flag in fstab but by
calling `btrfs property set / ro true`).
You may have to mount the root file system rw again for this operation
to succeed, or call it directly on the snapshot directory in
/.snapshots/xxx/snapshot).
Cheers,
Ignaz
--
Ignaz Forster