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Recovering System after upgrade

Usually upgrades are binary: either they work or they don't. Actually, my experience with SME upgrades has been very good: I've only had a very few where the upgrade process didn't work at all. In those cases, you install new, apply all applicable blades, and then restore from backup. That's annoying, but fairly simple.

But what happens when an upgrade appears to be fine, but a few days later you find that there is actually a serious flaw? That's a bit of a mess: any backup since the upgrade is suspect, but there has been new mail and perhaps other new user files since then that you don't want to lose.

There is a way out, of course. The first thing to do is to stop more incoming mail: "svc -d /service/smtpfront-qmail" will stop SMTP from accepting new mail. Next, check the queue with "/var/qmail/bin/qmail-qstat" and be sure everything has been delivered before proceeding. You can manually examine any messages in the queue if necessary (something "stuck" might be a message you can easily recreate later if you want to get going now):

[root@mail queue]# /var/qmail/bin/qmail-qstat
messages in queue: 1
messages in queue but not yet preprocessed: 0
[root@mail queue]# cd /var/qmail/queue
[root@mail queue]# find . -type f 
[root@mail queue]# more ./mess/5/1713712

While you are waiting for the queue to empty, you need to do backups of the user directories:

cd /home/e-smith/files/users
tar cvf /tmp/myuserfiles.tar .

Put /tmp/myuserfiles.tar on some other machine or transfer it to tape or floppy.

Now do a fresh install of SME. Install all necessary blades and patch updates, followed by the backup (desktop or tape) that was made from the old, pre-upgrade system. The restore procedure is smart enough not to overwrite anything it should not. Finally, bring back /tmp/myuserfiles.tar, and

cd /home/e-smith/files/users
tar xvf /tmp/myuserfiles.tar

That should do it.

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