Hi,

I have been trying for a while now to create a Linux distro on a USB stick. The idea is that I could just plug it into any machine and have my familiar setup and data. I've been using Ubuntu and I initially started with a USB live setup. This works fine but I was concerned from a security perspective:
- It doesn't allow you to set a root password
- All software updates are lost when you power down
A live install with persistence might solve some of these problems but Googling suggested that I would be better off doing a full install on a suitably large USB stick.
So this is what I did. From the Ubuntu Live USB instead of choosing 'Try Now' I choose 'Install' and install it to a second USB stick plugged into another USB port.
Relative to the Live USB this has solved the above two problems however it has created a new intermittent problem. At random intervals various programs will stop responding for a few seconds at a time (Ubuntu signals this by the associated window going dim). When this happens the 'top' command at the command line show a spike in the %wa field for the CPU which I believe indicates that it is waiting for disk I/O and the CPU% column in Ksysguard (KDE system monitor) will show 'disk sleep' rather than a percentage. I can't seem to find any resolution to this problem and I'm pretty sure it is not hardware specific, I have tried with two different 16Gb USB sticks and a number of different machines from a 10 year old laptop to a modern machine. The behaviour is the same:
- with the USB live key there are no problems, no program freezes
- With the USB full install there will be random freezes on all hardware tested.

So, finally, my questions:
- What exactly is Tails, a USB-live distribution of a full install on a USB stick? Most descriptions I have seen describe it as live but I find it hard to believe that it is a setup that doesn't facilitate setting a password and keeping your system patched given that its primary focus is anonymity/privacy/security
- If it is more like a full install on a USB stick were there any particular changes that needed to be made to make this work ?
- Were any problems like the freezing problem I have observed ?

Thanks,

Oisin.

The freezing is hardware related but is due to USB vs the flash drive itself. Is the drive plugged into a 1.1 or 2.0 port? A live Distro basically runs from RAM and depending on how it is built only accesses the USB drive if required. A full install will always need access the drive and if doing lots of I/O the system will seem to freeze at times. USB 1.1 is only 12Mbits/second. Modern PCs should be 2.0 or maybe 3.0 but 2.0 is still much slower than SATA. USB is a shared bus so any other device on the same port will effect speed.

Tails runs only from memory and has no access to any drives by default. You can't save or change anything and stated when you shut down all is lost. Tails does have a persistence option if so configured using encryption to keep data secure.

Hi michaelk,

Yes I had thought the USB speed might be an issue so when I created the 2nd 16Gb full USB install I got a USB3.0 stick and I have checked that my ports are also 3.0 cabable so they are in theory even faster than SATA 2.0 (5Gbps vs 3Gbps). Some have suggested that the overall speed is not the problem but rather the latency associated with each USB transaction which may be plausible.

Anyway, from what you say it looks like Tails is a live distro (with or without persistence). So my questions are:
- How does it handle security; can you set a root password ? How is the system patched, do you have to create an entire new image every time a bug is found ?
- When I see freezes I am not in general explicitly trying to save or read data. ie. I dont see the problem when launching programs. I'm just in the middle surfing the web etc., so the best explanation I had so far was that the browser was caching many small files all the time, each incurring a USB transaction latency, and this was what was causing the freezes. Presumably on a live distro firefox (and any other program) should be trying to do the same sort of thing but if there is no persistence then how is this handled ? Are all the programs in Tails configured not to write to disk ? Do they write to a RAM-disk or something else instead ?

Thanks,

Oisin

tails does have a way to upgrade to a new version which does include security fixes. I suggest reading the documentation.

https://tails.boum.org/doc/index.en.html