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We have been using Lubuntu/Ubuntu as a LiveCD image placed on a HDD formatted with ext3 file system. In the root of the file system we place a casper-rw file formatted for ext3. The casper-rw file is only 500MB in size. Everything in /dev/sda1, formatted as ext3.

Becaue of Skylake we have to update to 14.04.4 to get the proper kernel support.

Booting the liveCD image without persistance works just fine.

But, when we copy the .iso to the HDD(sda1) with ext3, create a 500MB casper-rw file, format the casper-rw file with ext3, then use grub-install to make the disk bootable, the boot fails to the busybox prompt. The logs there are saying it cannot fine casper-rw. This has worked with 14.04.1, 12.04, 9.04.

From web research it is very unclear if 14.04.4 still supports a casper-rw file. It seems that a disk partition with a casper-rw label is the preffered, only working method now.

If we create the second HDD partition, sda2, and set it up for persistance, everything magically works again.

So, the question becomes - Is using a casper-rw file in the root of the HDD(sda1), where the .iso image is located, still supposed to work? Or, it it a Casper bug?

Why is it an issue? There could be many, many pachines that might need re-partitioning.

Any help greatly appreciated!

  • just in case, here is a snippett of the grub.cfg file. It shows the boot option for persistant. Also, the ${iso} is replaced by the actual .iso file being used. set default="0" set timeout=5 #set root=(hd0,msdos1) menuentry "Normal ${iso}" { set isofile=/${iso} loopback loop (hd0,1)/${iso} set root=(loop) linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=/${iso} quiet splash persistent noeject -- initrd (loop)/casper/initrd.lz } – PicassoTKatt Jul 20 '16 at 17:30
  • Sorry for putting after last comment. Enter key posted. – PicassoTKatt Jul 20 '16 at 17:31
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Casper-rw files only work on FAT32 partitions thus the 4GB size limit. If you make a FAT32 partition and place the casper-rw file on it, Ubuntu will find the file while booting.

Better to use an ext casper-rw partition which is not limited to 4GB.

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