[conspire] mystuff on external media

Tony Godshall tony at of.net
Wed Dec 9 14:03:08 PST 2009

What ubuntu does with their ubuntu-on-a-stick is pretty easy.

Their "usb-creator" app optionally makes a file named casper-rw on the stick.

When you boot from the stick, it makes whatever's on the stick
available and when you shut down it makes any settings, files created,
etc., get put back in casper-rw.

I think they may even detect the stick's casper-rw if you boot from
dvd or cd (dvd+r is way faster than cd btw) but you'll have to check
on that.

To mount the casper-rw on a regular system to access the files do
something like this...

  # sudo mkdir -p /mnt/casper-rw && sudo mount -o loop
/media/(mounted-stick)/casper-rw /mnt/casper-rw

... poke around /mnt/casper-rw ...

  # sudo umount /mnt/casper-rw

By the way, be careful with using rsync -u with files on a bootable
usb stick- if you boot up on various computers it's quite possible
timestamps might be off and you could easily get "newer" older files
overwriting ...

Best Regards.

On Sat, Dec 5, 2009 at 4:55 PM,  <roger at rogerchrisman.com> wrote:
> I'm sure many of you have experience with this. Suggestions and tales welcome!
> I am experimenting with keeping a copy of my stuff (work in progress
> files, config notes, some images, some music and some reference files)
> on external media, in this case a USB thumb drive and or an SD card.
> Pros:
> - it's a backup of my work and current files
> - easy to take my files with me when I use different computers
> Cons:
> - if I lose my thumb drive who knows who might end up with my files
> - if it sticks out of the computer it might get whacked and broken
> - if I goof up my rsync invocation I could turn the disk(s) into a --toad
> My files aren't secrets and don't need to be encrypted. If thumb drive
> gets broken I can buy a new one. If toad, then reload from other
> computer or the other thumb drive.
> I'm experimenting with a USB thumb drive, and an SD card.
> - USB thumb drive is a 4Gig PNY metal swivel case USB thumb drive
> ($15.00 at Frys, thumb drive isle) that looks and feels sturdy and
> only sticks out 5/8th of an inch when I plug it in with its metal case
> swiveled 90 degrees instead of 180 degrees.
> - SD card is a 4Gig Kingston MicroSDHC flash card bundled with a USB
> adapter, an SDHC adapter and a MiniSDHC adapter ($21.00 at frys, other
> end of store in memory isle). I wanted to try this one because my
> laptop has a SC card reader slot in front that (a) has a transfer
> light that flashes when the SD card is being read or written and (b)
> caries the drive safely inside the computer with only 1/8th inch
> sticking out.
> rsync
> To sync files from the computer to the removable media:
> rsync -auv --del ~/mystuff /media/disk
> To sync the files from the removable media to the computer:
> rsync -auv --del /media/disk ~/mystuff
> Slow SD card reader
> For some reason the SD card reader in the front of my laptop is slow.
> Write speed to the MicroSDHC card in its SD card adapter there is
> ~270k/sec.
> Fast USB
> Write speed to the same MicroSDHC card but now in its USB adapter
> plugged into USB port in my laptop is *much faster*, ~9Mb/sec.
> Group permission not writable
> Both above removable media have their original FAT32 file system, with
> group permissions set to "root" user. I don't seem to be able to
> change their group permissions. This causes rsync to report inelegant
> errors when, per the -a flag, it tries to preserve my computer files'
> roger:roger permissions and fails to. Um, I gather FAT32 has no group
> permissions. What to do? I'd like to avoid routinely generating error
> messages of course.
> Anyone had success formatting flash media with a more UNIX oriented file system?
> What experiences have others had with this sort of thing?
> What command line invocations do you like for this kind of thing?
> Cheers,
> Roger
> Palo Alto
> (Laptop is an old, 2003, Compaq Presario X1000)
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