• The traditional time for major sysadmin work is the "dead time" between the departure of the summer students and the time the faculty starts preparing to teach the fall semester. August 15 falls right in the middle of that period.

• For the reasons given above, I'm going to do this at 12:45PM on a weekday.
• The traditional time for me to sysadmin work of this sort is usually the "dead time" between the departure of the summer students and the time of the faculty starts preparing to teach the fall semester. August 15 falls right in the middle of that period.

Mail Server Upgrade 15-Aug-2016

I propose upgrading the Nevis mail server on Monday, 15-Aug-2016, at 12:45PM Eastern Time. If all goes smoothly, the mail server will be down for no more than 15 minutes, then everything will go forward as before.

If things don't go smoothly: that's what the rest of the web page is for.

When

Why are you doing this in the middle of the day? Why not on Friday evening or some other time when it won't affect work?

If there's a problem with the upgrade, we all want to know about it right away. If I wait until the evening or just before the weekend, then you might be frantically trying to reach me in the middle of the night or when I'm away.

Go to lunch at 12:45PM. When you come back to your desk, the switch will hopefully be over.

How

If something goes wrong, how do we reach you?

I'll be at my desk, so you can call me: 914-591-2823.

If you want to use email (e.g., you want to cut-and-paste an error message and send it to me), as a backup you can use Columbia LionMail. Login with your UNI, and send e-mail to my UNI wgs1.

What

What exactly are you doing?

I'm upgrading the mail server to use CentOS 7, a free version of the Redhat Enterprise Linux operating system. The current mail server uses Scientific Linux 5, which is scheduled to lose technical support in 2017.

I chose CentOS 7 because that is the next Linux operating system that CERN will switch to (they presently use Scientific Linux 6). The differences between CentOS and SL are very minor anyway. CentOS 7 will be supported through 2024, so it will be a while before we have to do this again.

The upgrade will take only 15 minutes because I'm not doing anything to physical boxes. The mail server is kept on a virtual machine. I've already prepared the new virtual machine running mail services under CentOS 7. All I have to turn is turn off the old and turn on the new.

If you want to test the new mail server before it becomes official, go to your mail reader's configuration and add a 7 to the end of the server's name; e.g., mail.nevis.columbia.edu becomes mail7.nevis.columbia.edu, smtp.nevis.columbia.edu becomes smtp7.nevis.columbia.edu, etc. Don't forget to switch back before the date of the change! I've already tested the new server, but additional eyes can never hurt.

Where

Will I lose all my mail files?

No. Your mail files are not kept on the mail server virtual machine. They're kept on a different machine: see the pages on mail-related files and the list of machines; the directory /a/mail is on the central administrative server hypatia, not in the mail server virtual machine franklin.

It's vaguely possible that your mail reader may not display your mail temporarily because it loses track of your files (though this has not happened in any of my tests). Just restart your mail reader and everything should be fine.

If your mail files don't reappear, contact me.

-- William Seligman - 2016-08-05