Re: Problematic upgrade from 7.2 to 8.0 with ZFS file system

On 21/07/09 8:56 AM, Kip Macy wrote:
>> * lots of of clear documentation about what course of action a user should
>> >  follow if they are performing a source update. Should the recommendation be
>> >  changed to install userland*before*  rebooting, and then immediately reboot
>> >  before some of that userland explodes against the old kernel in memory?
> UPDATING explicitly states that the two need to be in sync or the user
> tools will not work.

Since I'm following the binary update process at the moment, I don't 
have UPDATING anywhere on my system. With the increasing popularity of 
Colin's freebsd-update, perhaps that file needs to be moved to / or 
somewhere else prominent and not in /usr/src

Also, if the notes say "tools will not work" that should be upgraded to 
something stronger, like "you will not be able to reboot if you have 
installed any part of your operating system on ZFS". To me, 'tools' 
sounds like 'you will not be able to run "zpool status"'.

>> >  The existing recommendation is based on the fact that the new kernel will
>> >  continue to work after reboot with the old userland.
>> >  If that assumption is
>> >  not always true then the whole FreeBSD installation process needs
>> >  rethinking.
> I don't think so. It is well understood that ZFS is an external code
> base, and like any third party application, users need to to inform
> themselves when updating. Just because it works fairly well, I don't
> think we should mislead ourselves in to believing that all the rough
> edges can be removed in the near future.


It isn't a third party application like something out of the ports 
system and FreeBSD users have grown to love how everything in the base 
distribution works together so well. This is the first time in my 15 
years of FreeBSD usage that an upgrade through major releases has had 
any problem for me, and I don't think it can be written off as "this 
isn't really part of FreeBSD, so it doesn't count." Users don't see the 
difference between parts of the FreeBSD system depending on their heritage.

That said, you and the other developers have done a fabulous job to get 
us all ZFS in our favourite operating system. Thank you. Given that 
you've said keeping backward ABI compatibility is too hard to achieve, 
then I think the only answer is lots of clear documentation. I am an 
avid FreeBSD user, read the lists and keep myself informed, but I didn't 
see any warning in the places where it would have helped me.

Are you saying that it is generally more dangerous to install world 
before rebooting? Would it be safer to:

1. reboot to single user (so there aren't many userland applications 
running)
2. install both world and kernel
3. reboot

My only suggestions are improving the freebsd-update tool (is Colin 
Percival reading this?) to give relevant feedback, moving UPDATING to 
somewhere useful for non-source updaters and ensuring the docs clearly 
state the seriousness of this particular issue.

For myself, I know what to do now, so my suggestions are purely to help 
others avoid similar difficulties.


Cheers
Ari Maniatis




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