[j-nsp] Old JunOS upgrade path

[adamv0025 at netconsultings.com]

> Saku Ytti
> Sent: Sunday, March 10, 2019 2:49 PM
> 
> On Sun, Mar 10, 2019 at 4:30 PM Tom Beecher <beecher at beecher.cc>
> wrote:
> 
> > was when it was shut down. ( Hopefully. :) ) When you upgrade it, the
> > process only modifies certain components. Any OS upgrade process like
> > that
> 
> This is not true, the upgrade is fresh install. It is not like you do
upgrade on
> your laptop FreeBSD or Linux.
> 
> Equivalent on your laptop would be that you keep your config in directory
> /config, have that in partition you don't touch then reinstall new FreeBSD
on
> your system partition and remount that /config partition. You just lost
all the
> programs you've installed outside base system and any other changes you've
> done outside /config.
> 
> Your laptop FreeBSD doesn't know what exists in the system what data has
> been changed, what has been installed it can't just steamroll the
installation
> with new, so it'll reinstall new stuff on top of old one for the things it
knows
> about. Juniper doesn't have this problem, they know what is the state of
the
> system so they can just streamroll it and they do.
> 
> 
Hmm looking at my old junos upgrade procedures form 12 to 15 I found the
following statements:

Upgrading from 12.3xxxx to 15.1xxxx upgrades the FreeBSD version from 6.1 to
10.0. 
Upgrading from 12.3xxx to 15.1xxx reformats the file system. Only specific
files and directories are preserved. 
Only specific files and directories are preserved unless precautions are
taken. 
Juniper document reference that states the above is:
http://www.juniper.net/documentation/en_US/junos/topics/task/installation/ju
nos-os-upgrading-kernel-freebsd10.html

Since the JUNOS upgrade is from JUNOS with FreeBSD kernel version 6.1 to a
JUNOS with FreeBSD kernel version 10.0, there is a requirement to upgrade to
an intermediate JUNOS version (13.3 or 14.2) first. Table 1 in the following
Juniper document reference quotes it:
http://www.juniper.net/documentation/en_US/junos/topics/task/installation/ju
nos-os-upgrading-kernel-freebsd10.html

On the backup RE1, the configuration compatibility against the 15.1xxx
software release cannot be performed due to upgrading from JUNOS software
with FreeBSD 6.1 to a JUNOS software version with FreeBSD 10.0.  Therefore
skip the validation using the JUNOS CLI command "request system software add
/var/tmp/junos-install-mx-x86-64-15.1xxxxtgz no-validate". Do not use the
"reboot" option here as this is not supported for this type of software
upgrade.

In order to avoid PR(not externally available) we need to deactivate config
related to console before doing upgrade to 15

So yeah there's a lot of stuff to pay attention to.
I suggest you read the release notes, section Basic Procedure for Upgrading
to Release to find more info and more documentation.
Oh and always test the upgrade in lab -to avoid running into nasty PRs in
production during the upgrade night.
And best approach is to have pre-upgraded REs

adam