How to persist boot messages on Fedora13 USB live image?

[csharpp]

I've a headless custom device that boots from USB using live image. Since I cannot access the device through the network, I need a way to persist boot related log files (dmesg, boot.log, messages) to view them on another computer. I also need to know how can I run custom commands on startup of live image. Thank you.

[JosePF]

Hi,
i dont know if it is the best way but most easy is:
create usb live with unetbootin of fedora.
Go to Index of /diskimg and download one of the files (128mb.zip, 256mb.zip, or 512mb.zip) corresponding to the mount of persistent space you want (make sure the size of the persistent disk image is smaller than the free space you have on your USB drive).
Now extract the file "casper.rw" from the zip file to your USB drive.
(This file is a ext2 file system, you can resize it if you need).

Add persistent in kernel line boot in sysconfig.conf.

This way you have a usb that uses casper-rw as a persistent file system when its needed.

I hope this is what you want.
Regards

[csharpp]

I've tried Fedora Live USB Creator with persistent layout, but the persistent layout was empty after boot. How can I redirect boot message files to the persistent layout?

[JosePF]

Hi,
how have you create usb live?
Following fedora wiki:

Data Persistence

Data persistence means that your files and settings will remain even after you reboot your live system. You can perform updates just like a regular installation to your hard disk except for kernel updates which are not supported. The primary use of this feature is booting a USB stick with your live image as well as the persistent changes.

Use liveusb-creator, a graphical utility to do this easily. Liveusb-creator is available in the Fedora repository and for Windows users as well.

If you prefer the command line, you can run the following command:

$ livecd-iso-to-disk --overlay-size-mb 512 /path/to/ISO /dev/USBPARTITIONNAME

where 512 is the desired size (in megabytes) of the overlay. The livecd-iso-to-disk shell script won't accept an overlay size value greater than 2047 for VFAT, but for ext[23] filesystems it is only limited by the available space. You can find the livecd-iso-to-disk shell script in the LiveOS directory at the top-level of the CD image. Note that you'll need to have space on your USB stick for the live image plus your overlay plus any other data you want on the stick.
Limited Lifetime of Persistent Overlay
One very important note about using the "primary" persistent overlay for system changes is that due to the way it's currently implemented (as a LVM copy-on-write snapshot), every single change to it (writes AND deletes) subtracts from its free space, so it will eventually be "used up" and your USB stick will no longer boot. Because of these limitations, it is advisable to use the system-level persistence sparingly, for configuration changes and important security updates only. For a truly persistent write-many (vs write-once) overlay, use the --home-size-mb option to create a home directory filesystem image for personal files. Unlike the primary system overlay image, the home.img can be re-used and loop mounted outside of the liveusb environment.

The persistent overlay status may be queried by issuing this command on the live system:

dmsetup status

The returned value may look like this:

live-osimg.min: 0 8388608 snapshot 2352/2352 24
live-rw: 0 8388608 snapshot 42296/204800 176

I dont know if Fedora Live USB Creator save logs, but unetbootin method do it.

Regards