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What to expect from do-release-upgrade LTS->LTS (duration, problems, config adjustments, ...)?

rated 0 times [ 4] [ 0] / answers: 1 / hits: 3253 / 3 Years ago, mon, may 3, 2021, 5:09:34

I have a productive Ubuntu Server LTS webserver ("classical" LAMP) running 12.04.5 LTS (up-to-date, regular apt-get update && apt-get dist-upgrade). I can only access it via SSH (rented server with root access). I do not use any third-party software/sources, only the official Ubuntu ones.

I'd like to run do-release-upgrade to upgrade to 14.04.X LTS.

My question is what I can expect from this process to keep the downtime at a minimum:

How long will the LTS upgrade run (X minutes, X half-hours, X hours)? I know this depends on a lot of things, but a rough time-scale would be nice to know beforehand (it's very fast hardware and network connection).

are reboots needed inbetween (-> SSH-only-access)?

is constant user-input required?

Will the updated important services (Apache, PHP, MySQL) just run or can I expect to have to update a lot of configuration files (if so which are likely needing adjustments)?

Are there any other known problems that occur often on a big LTS upgrade?

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1 Year ago

answered 3 Years ago whipstder · Accepted Answer

How long will the LTS upgrade run (X minutes, X half-hours, X hours)? I know this depends on a lot of things, but a rough time-scale would be nice to know beforehand (it's very fast hardware and network connection).

Last time I did this it took just over 1/2 an hour. On a more than average internet connection. But indeed this will depend on a lot of things. If you have a desktop installed it will take longer. If you have more software installed than me it will take longer. If you have less installed it will take less time.

Are reboots needed inbetween (-> SSH-only-access)?

Not when I did it and as far as I know the upgrade is done as 1 action. So a reboot at the end will be needed.

Is constant user-input required?

No. But you probably want to watch most of the process as it happens.

Will the updated important services (Apache, PHP, MySQL) just run or can I expect to have to update a lot of configuration files (if so which are likely needing adjustments)?

It did for me: apache and mysql ran instantly afterwards; but this largely depends on your setup; if you used deprecated options that got deleted in 14.04 those might give you troubles.

Both apache and mysql show clear messages if it does crash.

One thing I would advice: stop any services yourself and make a backup of the configuration files before you start the upgrade. Make a database dump, backup my.conf and /etc/apache2/conf, sites- etc.

Are there any other known problems that occur often on a big LTS upgrade?

Yes, power outage. It seems to be very popular just when you start an upgrade for power outages to happen. So as with any major changes of your system: backup and check that you can restor it.

One other thing: after I did the upgrade on 1 machine we made an educated guess to what it would cost our company if the upgrade would bork. We decided it would be cheapest and safest to buy a new server and change the old one to a fallbackup server. That also made the upgrade easier: we could mess with apache setting, mysql settings and restore our backups. It took longer than an hour (days) but it was possible to do this during daytime and when we wanted it.