Does anyone reuse /boot or /var partitions ?

[Eric Blake]

On 01/22/2015 02:36 PM, Adam Williamson wrote:
> There's a proposed anaconda patch ATM which would disallow mounting an 
> existing partition as /boot or /var (or any subdirectory of those 
> except /var/www ) without reformatting it. i.e., you can't reuse an 
> existing partition with those mountpoints.
> 
> I'm curious to know if anyone / many people do this, and if so, if 
> there's a particularly good use case for it; if so, we might want to 
> provide that feedback to the anaconda folks.

Yes, I very recently reused the /boot mountpoint when installing a fresh
F21 build on top of an earlier F19 install, where I thought it was
easier to start fresh than do incremental upgrades.  Since my machine is
multi-boot, my F19 install had stored grub directly into /dev/sda1 (the
/boot partition) rather than the overall drive /dev/sda (that was
reserved for my master bootloader that then chainloads the appropriate
/boot according to which OS I would be booting).  Since newer Fedora
installation no longer allows per-partition grub installation for easy
chainloading, all I had to do was remount the old /boot, tell anaconda
to not install any bootloader, then manually touch up /boot/grub2.cfg to
point to the new install's kernel version, without having to futz around
with reinstalling grub into the /boot partition.

But I'm in a minority, and I know that chainloading multi-boot installs
is already in the fringe.  I'm perfectly capable of getting my system to
work if /boot is forced to be wiped rather than reused, even if it is
more of a hassle on my end.

> 
> There are a few references to using shared /boot on Google, but not 
> that many, and mostly for crazy multiboot configurations that we 
> really don't want to be stuck dealing with. Does anyone know of a 
> really sensible use case for this?

I didn't think my situation was that crazy.  But you anticipated my use
case :)

> 
> For the record, this is actually re-hooking up code that was used in 
> oldUI - that is, F17 and earlier - but in oldUI it just produced a 
> warning you had to click through; the current patch flat disallows it. 
> The main driving force for this is 
> https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=1074358 , as it 
> keeps turning out to be annoyingly tricky to make sure that only newly-
> installed kernels have their initramfs regenerated when installing to a
> shared /boot partition.

Ah, a good reason for a forced wipe of /boot.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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