So, I've spent the last day going through similar questions, and can confirm first that this is not a duplicate of:
- Ubuntu Live-USB Using a "casper-rw" Partition
- Persistent Ubuntu 14.04 USB fails to boot after creation of ext4 casper-rw partition
With that out of the way: I've created an Ubuntu 14.04.03 Live USB Flash Drive (32GB) using UNetbootin, as well as the Ubuntu Startup Disk Creator. In both cases, I was able to successfully deploy my Ubuntu ISO (which I've confirmed is intact via
md5sum analysis). In both cases, persistence worked successfully (I had to manually enable it when using Ubuntu Startup Disk Creator, but UNetBootin adds the
-persistent kernel argument automatically to
syslinux.cfg), no problems.
I need to have a persistence file larger than 4GB, as I'm creating a bunch of these flash drives for Field Application Engineers (FAEs), and they need to be able to use them on the road to diagnose installations for custom systems my company currently supports. It's fine if they burn out due to excessive write cycles, and each FAE gets a dozen of them if needed for each trip.
Also, we need to keep the first partition on the disk as a FAT partition in case the FAE needs to drop files onto the disk from Windows, Mac, Linux, etc, as Windows machines refuse to mount FAT partitions on a flash drive unless they are the first and only FAT partition on the disk.
I've tried the steps in the following articles:
- How to make a persistent live Ubuntu USB with more than 4GB
- How do I get a live-USB to use a partition for persistence?
The instructions were clear:
- Create a Live USB flash drive with Ubuntu, leaving space for an extra partition.
- Delete the
casper-rwloopback file on the first FAT partition on the flash drive.
gpartedto create an
ext2/ext3/ext4partition after the FAT partition, and give it a volume lable of
I followed all of the advised steps, but booting fails. When I attempt to boot from my newly-created flash drive, I am directed to a prompt instead of Ubuntu properly booting, though I briefly see the graphical Ubuntu startup screen animation.
dmar: IOMMU: failed to map dmar0 ACPI PCC probe failed. BusyBox v1.12.1 (Ubuntu 1:21.0-1ubuntu1) built-in shell (ash) Enter 'help' for a list of built-in commands. (initramfs) _
I've gone through the Ubuntu bug tracker, and it seems that this issue has been observed by numerous others:
And that it has been solved, so I should expect the fix to already be in my Ubuntu 14.04.03 image:
I've also tried updating my kernel boot parameters, by inserting
LIVE-MEDIA=/dev/sdd1 (in my case) at boot time by hitting TAB, ie:
kernel /casper/vmlinuz.efi initrd=/casper/initrd.lz file=/cdrom/preseed/ubuntu.seed boot=casper LIVE-MEDIA=/dev/sdd1 -- persistent
This time it at least finds the boot partition and starts attempting to boot the Live USB disk, but seems to fail along the way, with a bunch of "casper" related warnings. I can't seem to save those logs though, so I'm unable to provide them at this time. My current default kernel arguments are:
label ubnentry1 menu label ^Try Ubuntu without installing kernel /casper/vmlinuz.efi append initrd=/casper/initrd.lz file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash -- persistent
How can I go about resolving this issue?