Combining replies to Allen and Matthias. On Thursday, June 07, 2012 17:29:16, Allen wrote: > On Thursday, June 07, 2012 03:42:55 PM Chris Knadle wrote: > > I'll mention this even though I'm not necessarily suggesting > > it -- sometimes it's possible to use a shared "test" /home > > partition and a single swap partition across several > > distributions. A shared /home partition can work where > > the software used is of similar version levels. An example > > of where this becomes strange is if the /home partition was > > installed by Ubuntu which uses AppArmor, but then the same > > /home partition is used by Fedora which expects files to have > > extended attributes for use with SELinux which are now > > missing. [It's sometimes possible to add the extended > > attributes later, and they may or may not be necessary for > > /home depending on the SELinux policy being used.] > > Based on my multiboot experience, I think it is safer to begin by not > trying to share swap or /home partitions among distros, or at least to > investigate it via google search. > > In 2008 I tried to share a swap partition between Fedora and Ubuntu. > Originally the PC had Fedora only. I then installed Ubuntu and instructed > it to use the same swap partition as Fedora was using. Subsequently, > Fedora would boot but KDE froze and gkrellm reported zero swap space. > I found a thread in Fedoraforum "sharing swap partitions with kubuntu". > I ended up giving up on trying to share a swap partition among distros. > (I didn't pursue trying to understand the reason for the failure.)
Interesting. That's an issue I hadn't considered. There's a possibility that either Fedora or Ubuntu was configured to do LUKS encryption on top of the swap partition, and thus the other distro couldn't use the swap without some detailed manual configuration for swap atop LUKS. Based on the links below, the Ubuntu 7.10 "alternate installer" for Ubuntu from Oct 2007 had this as an install option, so this has been a possibility at least since then. https://wiki.ubuntu.com/EncryptedFilesystems (For Ubuntu release dates) https://en.wikipedia.org/wiki/Ubuntu_(operating_system)#Releases Not sure, but I seem to recall someone telling me that Ubuntu of today encrypts the /home [and possibly the swap] partition by default. What I do know is that when partition encryption is used, it works differently on Ubuntu than it does on Debian. LUKS encryption on Debian is a non-default install option, and when chosen the decryption is done within the initrd.img init script at boot time. When encryption is used on Ubuntu, home directories (or the /home partition, I don't recall which) is decrypted when a user logs in. However barring that, my experience has been that normal unencrypted swap partitions work across different distributions. A common use case is booting a LiveCD to rescue a local Linux system. LiveCDs tend to use the swap partition on a local disk if it finds there's one available. > IIRC, I investigated via google search the possibility of sharing /home > among distros. The immediate result was that this won't work. The apps > have hidden files (dot files) on /home. For example, Firefox on distro A > will conflict with Firefox on distro B. I agree that it can be problematic, but I have heard of it work. Where this is known to get dicy is shared /home with a combination of old and new distributions due to local settings for software (dot files) having "desired differences" from the software between distributions being different versions. Local settings are likely to bet different between Firefox 10 vs Firefox 3.5, for instance. So there's the possibilty for "local setting clashes". Separate /home areas is obviously the safer option, but uses more space. On Thursday, June 07, 2012 17:41:01, Matthias Johnson wrote: > I would think you could have ownership issues with a shared home as well as > user setting configs. > > Matthias Yes that's definitely possible (and I have run into this myself), but it can be worked around if necessary. Usually the first UID and GID allocated is 1000, and if that's the case then the ownership will match. If it doesn't, then the /etc/passwd and /etc/group files for the distribution that clashes can be edited to fix this. [I remember doing this, but it's been a long time now.] -- Chris -- Chris Knadle [email protected] _______________________________________________ Mid-Hudson Valley Linux Users Group http://mhvlug.org http://mhvlug.org/cgi-bin/mailman/listinfo/mhvlug Upcoming Meetings (6pm - 8pm) Vassar College Jul 11 - Mad Science Fair - Open Hardware Expo Aug 1 - Pimp My Network Sep 5 - OpenStack
