Ubuntu releases a new version every 6 months. We usually only upgrade once each year. Ubuntu's current release (14.04...trusty tahr) has been out since April 2014.
Each summer we upgrade all servers and reinstall all lab machines. This takes a few weeks to do, so there will be times during the summer when not all machines are running the same version of ubuntu.
When reinstalling the lab machines, disks are repartitioned and all data on the /locals is usually lost. I will try to warn all /local users before a machine is reinstalled.
Here is a rough schedule for this summer:
$ for i in 6 7 8; do cal $i 2014; done
June 2014
Su Mo Tu We Th Fr Sa
1 2 3 4 5 6 7 <-- test installs of 14.04 on
8 9 10 11 12 13 14 various lab machines
15 16 17 18 19 20 21 <-- Jeff on vacation 13-22
22 23 24 25 26 27 28 <-- SWITCH to new ALLSPICE
29 30
July 2014
Su Mo Tu We Th Fr Sa
1 2 3 4 5 <-- begin ubuntu 14.04 installs
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 31 <-- other server installs/upgrades:
/scratch, condor, oldspice, etc
August 2014
Su Mo Tu We Th Fr Sa
1 2
3 4 5 6 7 8 9 <-- clean labs, prep for classes
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31 <-- first day of classes....