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-   -   2 operating systems, extra partition shared between them? (https://www.linuxquestions.org/questions/linux-newbie-8/2-operating-systems-extra-partition-shared-between-them-845411/)

igadoter 11-23-2010 04:53 AM

Hi,
I think that the only solution is to create the common partition with vfat or ntfs. These systems are good for
them there should be no problems with permissions. Shared partition is in fact some kind of a file server. <different
systems have access to the same data. Under *nix sharing partition is complicated due to permissions. Say on each
your system 'users' group will have to have the same gid number.

acraig 11-24-2010 02:27 AM

Please explain
 
Hi igadoter,

Thanks for the suggestion, but I don't understand how reformatting the partition from ext3 to ntfs/vfat will prevent the partition from being visible on the desktops.

I believe I mentioned this earlier, but if I didn't, the drive is visible on both OS desktops. I'm most concerned about changing this in Dreamlinux because I am most comfortable and experienced with tweaking it, and figured I could work out the second OS later. BTW, the 2nd OS is Ubuntu 10.04.1 and both have Gnome desktop manager.

The partition is mounted in the same spot in their separate homes, but also shows up on each Desktop, even though they are not mounted in /media. I've checked /media, in both OS, multiple times to be certain. They were only visible in media before I permanently mounted them and added them to fstab and /mnt. Not sure if this matters, but thought I should let you know in case it does.

Also I am wary of having a media only drive that uses such a completely different file system from what I used when I ripped and saved the videos (especially one I associate with Windows). I know this can affect data because it has happened to me before -- and that was only the difference between ext2 and ext3, which you wouldn't think would make a difference. In that case it was my address books backups. I couldn't email to anyone in them (unless I manually typed in their address), until I went back to ext3.:scratch:

I'm starting to think this is just some Gnome thing, since people with KDE don't have this problem. Although, when I was using XFCE (also in Dreamlinux-3.5) the file system itself was visible on the desktop, and in Gnome (both Dreamlinux and Ubuntu) it is not.

igadoter 11-24-2010 05:42 AM

Quote:

Originally Posted by acraig (Post 4169163)
I believe I mentioned this earlier, but if I didn't, the drive is visible on both OS desktops.[

For me these are desktop settings. Like icon for USB stick. As I remember even not mounted are visible: If you connect USB stick before a system will start you will find an icon for USB drive on desktop as unmounted device.

Quote:

Also I am wary of having a media only drive that uses such a completely different file system from what I used when I ripped and saved the videos (especially one I associate with Windows).
vfat is widely used for USB sticks when used as data storage. I suggested ntfs because it is easy to mount this file system without restrictions.

Quote:

I know this can affect data because it has happened to me before -- and that was only the difference between ext2 and ext3, which you wouldn't think would make a difference.
It sounds very strange. I think it is worthy to post an additional thread about this situation.
Maybe this way you would find an explanation. I think there are many ways data can be broken.

acraig 11-25-2010 01:06 AM

Quote:

Originally Posted by igadoter (Post 4169314)
For me these are desktop settings. Like icon for USB stick. As I remember even not mounted are visible: If you connect USB stick before a system will start you will find an icon for USB drive on desktop as unmounted device.

I agree that it is a desktop settings things -- someone else mentioned this as well, but it's not something I can change. I've searched high and low and found nothing that would allow for a change in desktop icon mounting, except what I've mentioned previously.

When I checked the Ubuntu forum last night, I read a post where someone was told that any new drive/partition they added to the OS "should automatically be visible on the desktop" and Ubuntu's default desktop is Gnome. Other versions have different names like Kunbuntu and Xubuntu... but you probably knew that.

Quote:

Originally Posted by igadoter (Post 4169314)
vfat is widely used for USB sticks when used as data storage. I suggested ntfs because it is easy to mount this file system without restrictions.

I use nearly a dozen flash drives, all vfat, and all visible on the desktop. Wouldn't changing file systems be a waste of time and energy (I have nearly 200GB on the new partition and it took a long time to transfer all that data), since the vfat/ntfs drive would still be visible on the desktop, as this is a desktop settings problem?

acraig 11-25-2010 01:09 AM

Quote:

Originally Posted by igadoter (Post 4169314)
It sounds very strange. I think it is worthy to post an additional thread about this situation.
Maybe this way you would find an explanation. I think there are many ways data can be broken.

You don't think it was a file system change problem?
Thing is, when I switched back to ext3, I used the same files I attempted to use in ext2... which were created in ext3.

igadoter 11-25-2010 08:06 AM

I don't know. But I thought that if you afraid of loosing your data maybe there is a chance to use network protocols to copy files. I meant to post a thread about your suspicions - that passing from one files system to another one may broke your data. I am also interested in if it is possible.

markush 11-25-2010 08:28 AM

Hi,

I'm dualbooting with Gentoo, Arch and Slackware. I have one shared partition which I mount in "/usr/local/public". The filesystem is ext4, but it doesn't matter if it were ext3.
FAT filesystem is improper if one has no Windowssystem on the same machine. The problem is that on FAT systems there are no permissions, all files are executable and writeable for everyone from Linux. This is very inconventient and dangerous. Also when copying data from a FAT system into a Linuxfilesystem like ext3 the permissions are still set to everything executable.
Another point: if you build your own kernel, be sure to configure for all filesystems you are using. What I mean is if you (for example) have a distro which comes with ext3 as default filesystem, and you have an ext4 shared partition it may be that the kernel can't see the shared partition.

Markus

acraig 11-26-2010 12:53 AM

That's a good idea...
 
Quote:

Originally Posted by igadoter (Post 4170747)
I don't know. But I thought that if you afraid of loosing your data maybe there is a chance to use network protocols to copy files. I meant to post a thread about your suspicions - that passing from one files system to another one may broke your data. I am also interested in if it is possible.

I think I will start a thread on it. I may want to use ext4 or something else in the future and I want to know for sure if my backup files will work on a new file system. Thanks, for the suggestion.

acraig 11-26-2010 12:58 AM

That is good to know
 
Quote:

Originally Posted by markush (Post 4170783)
Hi,

I'm dualbooting with Gentoo, Arch and Slackware. I have one shared partition which I mount in "/usr/local/public". The filesystem is ext4, but it doesn't matter if it were ext3.
FAT filesystem is improper if one has no Windowssystem on the same machine. The problem is that on FAT systems there are no permissions, all files are executable and writeable for everyone from Linux. This is very inconventient and dangerous. Also when copying data from a FAT system into a Linuxfilesystem like ext3 the permissions are still set to everything executable.
Another point: if you build your own kernel, be sure to configure for all filesystems you are using. What I mean is if you (for example) have a distro which comes with ext3 as default filesystem, and you have an ext4 shared partition it may be that the kernel can't see the shared partition.

Markus

Thanks for the information! I did not know that. So glad I joined LinuxQuestions. :newbie:

igadoter 11-26-2010 07:34 AM

Quote:

Originally Posted by markush (Post 4170783)
Hi,
The problem is that on FAT systems there are no permissions, all files are executable and writeable for everyone from Linux.

This is exactly why I suggested to use FAT. The simplest problem is when the gid of users groups differs for different systems.
For one of them a file with that gid belongs to users group but for others there can be no at all a group with that gid.
Management for uid and gid is for some distros predefined - one cannot change it easily.

markush 11-26-2010 11:01 AM

Quote:

Originally Posted by igadoter (Post 4171730)
...The simplest problem is when the gid of users groups differs for different systems.
For one of them a file with that gid belongs to users group but for others there can be no at all a group with that gid.
Management for uid and gid is for some distros predefined - one cannot change it easily.

I think that it is sufficient when root has writeaccess to the files on the shared partition. It is no problem to create files for the shared partition as a normal user and then as root to move them onto the shared partition. All members of the group "users" can have read/execute access.
And if you have the described problems with different group ids, why don't you create a new group with a unique id for both OSes? For example create a group "mylocalusers" and give it any id which is not yet used on both systems. Create this group for both OS. This should meet your requirements.

Markus

igadoter 11-26-2010 11:25 AM

Quote:

Originally Posted by markush (Post 4171908)
And if you have the described problems with different group ids, why don't you create a new group with a unique id for both OSes? For example create a group "mylocalusers" and give it any id which is not yet used on both systems.

You are quite right but it is not a simple solution.

mryuck 11-26-2010 12:22 PM

I havent used gnome in a while but if I recall
Code:

gconf-editor
Under Apps->Desktop or nautilus->desktop (I can't remember exactly where)
you should be able to turn off volumes-visible.

I've done this before, I think it only works on drives mounted at boot.

acraig 11-27-2010 07:08 PM

Quote:

Originally Posted by mryuck (Post 4171964)
I havent used gnome in a while but if I recall
Code:

gconf-editor
Under Apps->Desktop or nautilus->desktop (I can't remember exactly where)
you should be able to turn off volumes-visible.

I've done this before, I think it only works on drives mounted at boot.

I checked gconf-editor/Configuration editor and there was no volumes visible setting. I checked volume manager under apps/desktop and also schema/desktop and could not find anything that would make volumes invisible. Under desktop/gnome/volume manager there is a checkbox list that includes auto-mounting drives, but it's for removable drives and my partition is not removable. I'm thinking this is not what you meant. Or is it? Is there something I am missing/overlooking?

mryuck 11-27-2010 08:34 PM

press alt+f2.
Run gconf-editor.
Go to Apps->Nautilus->Desktop
There should be a show_volumes or volumes_visible or something key.

If there is not, something changed since I last used gnome.


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