LiveCD wiping root partition?

[Douglas McClendon]

Michel Salim wrote:
> On 01/08/07, Douglas McClendon <dmc.fedora at filteredperception.org> wrote:
>> Douglas McClendon wrote: 
>> Also, to answer your question more thoroughly than my first reply-  Yes,
>> after
>> the dd, if there is a seperate /usr or other partitions, files are then
>> copied
>> from / to there.  This is all very related to my turboLiveInst patch which
>> I
>> recently posted to livecd-list and anaconda-devel.
> 
> 
> Uh. Does it ensure that the root partition is at least 4.0 GB in size, or
> will it just try to dd the image regardless? I've had esoteric partitioning
> in the past, with small /, and large /usr and /opt partitions.


That it does.  Though the aforementioned turboLiveInst patch improves upon that, 
in that the rootfs only really needs to be 2.1G, which is the size of the 
uncompressed data that lives in the 4.0G filesystem image.  But as mentioned 
with that patch, that is still technically deficient for the case of separate 
/usr, where / needn't really even be 2.1G.  The solution to that is to have an 
alternate file level copy installation mechanism, rather than the (fast) block 
level fsimage copy installation mechanism.  This also fixes the potential 
problem of reintroducing support for non-ext3 (e.g. xfs) target root filesystems.

> 
> I'm surprised I don't remember hearing about this bug before.  I had
>> personally
>> run into the same warning you saw, but that is just a general warning that
>> has
>> nothing to do with the livecd installer case specifically, and the livecd
>> installer will stupidly let you just march along with the / fs not
>> scheduled for
>> formatting, even though it is going to anyway.
> 
> 
> I guess we really need to have different types of updates, where major and
> potentially data-loss-causing changes need to be more exhaustively tested.
> No one probably bothered testing a live CD install to a non-formatted
> partition before.

F7 was the _first_ fedora release to have a livecd installer.  And that generic 
warning about choosing to not format '/', probably steered most people away from 
doing that.  But I agree, this situation should definitely be a part of some 
sort of test matrix.

> 
> Still waiting for the dd process to finish backing up the partition to an
> external drive; will report if anything is salvageable. Wishing I did not
> blow away the Windows partition, would have made recovery much easier.
> 
> While we're on the subject of making Anaconda changes, how about putting
> /home on a separate partition? The BSDs traditionally do that, I think.

No doubt you mean by default.  Personally I've long been a fan of the single 
large partition (to the extreme of going out of my way to put boot, swap and 
suspend2 areas on /).  Though these days, I tend to favor the 'upgrades are 
never worth it', and 'wipegrades are the future'.  So /home makes more sense for 
'wipegrades'.  Although with all the version specific cruft that ends up in your 
homedir (~/.gnome*, blabla) I tend to have a subdirectory under home, and when I 
wipegrade, I only keep the subdir.  If I have any ~/.* files that are important 
enough, I keep a copy in the subdir, and a script to easily replace them after 
wipegrade (and gconftool2 to reintroduce all my desktop prefs).  Just my 
strategy, ymmv.

-dmc