Comment 17 for bug 1851123

Imho, the default behaviour should be overall read-only, as it's more in line with the general perception of a live system as an "I'm just looking" thing. Straying away from this concept could make more than a few people uncomfortable.

Moreover, having a default write behaviour can have adverse consequences in the long term. May a bug arise, there is an increased probability that it would behave destructively, especially considering that we're facing scripted automatic partitioning, which isn't quite the least potentially destructive operation.

On one hand, I understand there are use cases when people want to have installer logs handy on their stick, and having to pass "persistent" each and every time on the command line can be a problem. But On the other hand, there are people who don't want their USB stick written to for several reasons, one being to perform an integrity check before booting (such an unattended write operation would make subsequent integrity checks fail). The only option for these users is to remember adding "nopersistent" each and every time, and with no typing mistake of course, and not forgetting to interrupt the boot process, otherwise there's a write, and it's too late.

It seems to me there should be a solution to make both worlds happy, such as requiring people who want log persistence to pass "persistent" or why not "persistent-log" once on the command line. The system would then create the partition the way it's currently done by default, and during further boots with the default parameters, the system would check if a "casper-rw" volume exists on the live support, and if yes, mount it rw.

Additionnally, to address @cscameron's remark, it could be indeed useful to be able to limit the space automatically allotted to casper-rw on the live medium, such as defining an additional parameter to specify its size, either absolute or relative (as a percentage), but another solution that's already working is to create and format the volume manually (don't forget to label "casper-rw") and specify its size, which is a one time operation, hence should not be too much of a burden.