Systemd incompatible with mounted /usr [LWN.net]

Systemd incompatible with mounted /usr

Posted Mar 3, 2011 10:02 UTC (Thu) by peter-b (subscriber, #66996)
In reply to: Systemd incompatible with mounted /usr by russell
Parent article: Quotes of the week

I'm just going by this thread on the systemd mailing list. Says Lennart:

It's just a statement of fact, as a warning. Thinks like locale, certain udev rules, udisks, SMART, the pci db, the usb id, and a lot more have been broken since about always on seperate /usr.

The only thing that is new here is that we now print a warning that things are broken. The fact that it is broken didn't change. And hence I see little reason to add this to the release notes.

Also, it's just a *warning*. If you ignore it then things will continue to work as well or badly as they have been doing before.

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Systemd incompatible with mounted /usr

Posted Mar 3, 2011 10:27 UTC (Thu) by roblucid (subscriber, #48964) [Link]

Well mentioning those problems, would be much more sensible than saying, "not supported" and warn of "things breaking in mysterious ways". It's spreading FUD by being mysterious and non-specific.

If you have to have /usr in same FS as /, then there's no point anymore in /usr/{bin,sbin,lib}, in single user mode /usr is generally mounted.

If things like "locale, certain udev rules, udisks, SMART, the pci db, the usb id" are required for init(8) before /usr is mounted then that stuff should be under / instead. If someone fixes this error, how would someone see that systemd warning is no longer required?

Traditionally /usr was mountable read only, except during OS updates and being able to put / & /usr on different disks could be nice system optimisation.

With SSDs or flash based embedded systems, there's more reason to support multiple partitions and more than one system mount point, even if desktop developers don't see a need for it.

Systemd incompatible with mounted /usr

Posted Mar 3, 2011 20:12 UTC (Thu) by mezcalero (subscriber, #45103) [Link]

Oh, right. The usual complaint about "there's no documentation". Well, it's kinda unfounded, since the README explains the background of the warning:

http://cgit.freedesktop.org/systemd/tree/README

Systemd incompatible with mounted /usr

Posted Mar 4, 2011 10:53 UTC (Fri) by rvfh (subscriber, #31018) [Link]

The warning is visible against your will. The documentation needs to be searched for.

Please stop the RTFM stupidity and start giving proper information where and when it is needed.

Systemd incompatible with mounted /usr

Posted Mar 4, 2011 11:27 UTC (Fri) by rahulsundaram (subscriber, #21946) [Link]

As per demand,

http://cgit.freedesktop.org/systemd/commit/?id=aa1671320d...

Systemd incompatible with mounted /usr

Posted Mar 4, 2011 12:27 UTC (Fri) by rvfh (subscriber, #31018) [Link]

Thanks! And BTW, I can't wait to put my hands on systemd. Looks like the way to go IMVHO. Are we sure it will get in Fedora this time?

Systemd incompatible with mounted /usr

Posted Mar 4, 2011 12:52 UTC (Fri) by rahulsundaram (subscriber, #21946) [Link]

Your questions makes a assumption which I am not clear is true. Fedora 14 includes systemd. It is not the default but it is easy enough to try (yum install systemd, boot with init=/bin/systemd). Fedora 15 branch includes systemd as default and I don't see any reason it wouldn't be released that way. If you want to try it out, Fedora 15 alpha release is coming out shortly

http://alt.fedoraproject.org/pub/alt/stage/15-Alpha.RC2/

You can grab a nightly build from

http://alt.fedoraproject.org/pub/alt/nightly-composes/