Ubuntu ISO install - can't unmount /cdrom

MOH

I'm trying to install Ubuntu alongside Mint.
Mint is working fine, and through it I've mounted the ISO of the Ubunto install CD on a partition.

After lots of fiddling, got the grub menu updated, so when I boot I get the option to install Ubuntu, and that all works fine.

The installer is grand until the point where I choose the partitions to use. It then refuses to go any further and gives an error saying it can't unmount /cdrom (the partition it's running from). The partitions I'm choosing are in no way connected to that, but I'm assuming it needs to unmount all partitions in order to commit the changes.

This seems daft - there's instructions on the Ubuntu site on how to do this, yet the web is full of people with the same error.
If I could somehow get a terminal up I could manually unmount /cdrom while the partition change is in progress.

Has anyone managed to actually do this?

Stuxnet

mint IS ubuntu....whats the point running 2 ubuntu's?

human 19

MOH wrote: »

I'm trying to install Ubuntu alongside Mint.
Mint is working fine, and through it I've mounted the ISO of the Ubunto install CD on a partition.

After lots of fiddling, got the grub menu updated, so when I boot I get the option to install Ubuntu, and that all works fine.

The installer is grand until the point where I choose the partitions to use. It then refuses to go any further and gives an error saying it can't unmount /cdrom (the partition it's running from). The partitions I'm choosing are in no way connected to that, but I'm assuming it needs to unmount all partitions in order to commit the changes.

This seems daft - there's instructions on the Ubuntu site on how to do this, yet the web is full of people with the same error.
If I could somehow get a terminal up I could manually unmount /cdrom while the partition change is in progress.

Has anyone managed to actually do this?

If you are installing from the CD, then it needs to be mounted so the installer can read from it. It cant unmount because it is running...you are using it.
Why are you trying to unmount it?
Do you have sda selected as where you want to install the ISO, or sdb or some other, corresponding to the cd?

MOH

human 19 wrote: »

If you are installing from the CD, then it needs to be mounted so the installer can read from it. It cant unmount because it is running...you are using it.
Why are you trying to unmount it?
Do you have sda selected as where you want to install the ISO, or sdb or some other, corresponding to the cd?

I'm not explicitly trying to unmount it.

I'm trying to install Ubuntu as per the Install from Linux documentation.

Eventually found out it can't be done. There seems to be a bug which prevents committing changes to a partition as long as there's any partition currently mounted from the same drive. Which obviously there has to be, since the .iso is mounted there. So when you get to the bit where you select a partition to install to, it then gives an error message, and hangs.
Depending on exactly how you're going about it, you can possibly open a console and unmount the CD image just before committing the partition change, and remount it afterwards, but the wasn't an option for me. Ended up having to waste a CD.

The irritating thing is that the bug is 3 years old but not mentioned anywhere in the install guide.

human 19

Im trying to get my head around what you are tyying to do. Ive never had a problem installing about 20 distros over the last few years.

Mint is installed on sda1 (hard disk), yes?

You have an Ubunu iso on a cd. yes?

then what do you do after you switch the computer on?

MOH

human 19 wrote: »

Im trying to get my head around what you are tyying to do. Ive never had a problem installing about 20 distros over the last few years.

Mint is installed on sda1 (hard disk), yes?

You have an Ubunu iso on a cd. yes?

then what do you do after you switch the computer on?

Sorry, didn't realise the page I'd linked to covered multiple options.

Was trying to install without a CD - download the iso, and mount it on a separate partition (call it #1). Then edit grub to add that new partition to the boot options. Then reboot, and choose that partition to boot from. All of which went fine.

The problem is that when you reach the install stage of choosing a partition for the new install (call it #2), you get an error if the partition you choose to install to (#2) is on the same drive as the one you've just booted from (#1), as the installer can't seem to commit the partition change while your iso partition (#1) is mounted, which obviously it needs to be for the install to run!

(I know you can't install to the same partition you're running the installer from , but you should be able to install to a different partition on the same drive).

Johnboy1951

as the installer can't seem to commit the partition change while your iso partition

This is the bit I do not understand.

Are you making changes to the partitions when installing? That would explain it I suppose.

But I don't use Bunty so maybe there is some bug.

You *should* be able to prepare the partition/s to install to, before booting the Live OS.
Is there then an option to install to existing partitions without making any changes to those partitions, such as formatting etc ?

Not making changes to the target partitions while running Live, *should* allow the OS to install.

..... but as I said ..... no experience with the Bunty installer ....

pickarooney

Would you not use a memory stick if you don't want to waste 20 cents on a CD?

MOH

Johnboy1951 wrote: »

This is the bit I do not understand.

Are you making changes to the partitions when installing? That would explain it I suppose.

But I don't use Bunty so maybe there is some bug.

You *should* be able to prepare the partition/s to install to, before booting the Live OS.
Is there then an option to install to existing partitions without making any changes to those partitions, such as formatting etc ?

Not making changes to the target partitions while running Live, *should* allow the OS to install.

..... but as I said ..... no experience with the Bunty installer ....

Unless I was missing something in the installer, you select 'change' for the partition you want to mount, select '/' for where you want to mount it, and that's that. But even without anything extra like formatting, it still wasn't working

pickarooney wrote: »

Would you not use a memory stick if you don't want to waste 20 cents on a CD?

Because I needed it done in a hurry and I didn't have a memory stick or CD handy?


It's not a massive deal, it's just frustrating that the Ubuntu install documentation lists this as a valid way to install, while the forums are full of threads about the issue, and there's been a bug open for 3 years.

It does mention the issue as a footnote to the install process on this page, which isn't the one I was following originally, but the workaround requires a console, which I couldn't find any way of accessing during the install.

Oddly, when I did eventually get a CD and run the install, I got a number of steps in the process which I hadn't been presented with when booting from the iso, even before reaching the partition stage.

Bottom line: don't try and install from a mounted iso image, it's not worth the hassle.

Johnboy1951

Bottom line: don't try and install from a mounted iso image, it's not worth the hassle.

I obviously misunderstood ....... I thought you had run the ISO as Live session booting from HDD partition, and not mounted it from within a running OS.

MOH

Johnboy1951 wrote: »

I obviously misunderstood ....... I thought you had run the ISO as Live session booting from HDD partition, and not mounted it from within a running OS.

That *is* what I did.
I obviously made things worse by trying to explain it

Johnboy1951

Do they offer a different ISO for putting on a USB stick so that is can be installed from there?

If so maybe that ISO would work .......

croo

Did you try any of the workarounds mentioned in the link you provided? Or is that a different problem?

Note: if you unpacked the livecd on the same disk where you want to install Ubuntu, chances are you'll run into LP#288675, and be unable to select a partition. The workaround by Nick Spencer ("sudo umount -l -r -f /dev/sda3 or sudo umount -l -r -f /cdrom (where sda3 was the device mounted as cdrom)") is a rather terrible hack, but usable as a workaround.

Note2: Instead of using 'workaround', an alternative is to modify the file /etc/mtab by erasing the line that specifies the partition where the cdrom is mounted. This way the kernel thinks thats the /cdrom is not mounted and will not show the advice when installing ubuntu. I think this procedure is less dangerous than the one in the previus note.

Note3: Instead of the above 'workarounds', you may simply use the boot option live-media=/dev/sdb1 or LIVEMEDIA=/dev/sdb1, referring to the usb device holding the ISO. This would be the "bootable usb", even if your pc has a "buggy BIOS" and cannot boot from USB. The running kernel can access the USB device. This boot option is documented in http://manpages.ubuntu.com/manpages/karmic/man7/casper7.html, but unfortunately not supported by Ubuntu 11.10. Use the patch I filed as bug fix in https://bugs.launchpad.net/ubuntu/+source/casper/+bug/423616 while this is not yet put back in the ISO. Warning: this implies building a new initrd.gz which is not very trivial, although this forum has a good manual.

Wonder83

If you use Windows and just want to partition the drive another alternative is VMware player, download that and use as virtual machine. I use Ubuntu with VM player and works quite well.

MOH

Johnboy1951 wrote: »

Do they offer a different ISO for putting on a USB stick so that is can be installed from there?

If so maybe that ISO would work .......

I didn't have a USB stick handy at the time, so that wasn't an option

croo wrote: »

Did you try any of the workarounds mentioned in the link you provided? Or is that a different problem?

Since I was doing it manually rather than using unetbootin, couldn't find any way of getting a console so the first two options were out, and the third required a USB stick.

Ended up getting a CD and doing it the straightforward way.

goldendragon

I had the same problem, 3:00 pm, without usb stick bigger than 2gb, for ubuntu studio 12.04 instalation, so i solved that way, i create 2 partions at he hd 320 gb, the first one sda1 in ext4, the second sda2, in fat32 with the iso image bootable with unetbootin on it, restart the netbook, choose install, not defaut, before the choose of root at the partitioning, the same error about the cdrom moun, i ignore it, 2 times, so the instalation of ubuntu studio 12.04 proceeds normaly.