Dear LWP Users, lwp24, the home directory server of the LWP, will be rebooted next Sunday night. This will only take about two minutes, and it will happen between Sunday September the 18th 9:00 pm and Monday the 19th 7:00 am. But I don't yet know precisely at what time. Half an hour before the reboot, I'll send a notification mail to those who are logged in at that moment. Consequences ------------ If you are not logged in at the time of the reboot, then it has no consequences for you. If you leave your PC logged in but you are not at the keyboard, experience so far says that most likely you won't notice either. But if you remain logged in *and* you have processes doing I/O to your home directory, then you may notice a freeze during the reboot. And if your process(es) are doing enough I/O, they may even *crash*. How to still perform lengthy computations this weekend ------------------------------------------------------ If you have computations to run on your LWP that must be carried out this weekend, then please take the following measures: - Start the computing program from the shell instead of a GUI. Mathematica, Matlab and Maple all have command line interfaces that don't require X Windows. Sometimes particular options are required (see example below). - Before starting the program, cd to /mnt/D, so your working directory is on the hard disk of the PC, not in your home directory. Let the program do its I/O to the disk instead of $HOME as well, and copy the results to $HOME on Monday. - Use 'nohup' and/or file redirection so the program reads and writes to file instead of the terminal. - Use 'disown' to prevent Bash from sending the program a SIGHUP when Bash is stopped. - You may even log out now, the program will continue to run. - As an example: me@host:~$ cd /mnt/D me@host:/mnt/D$ nohup matlab \ -nosplash \ -nojvm \ -nodisplay \ < lenghty_computation.m & me@host:/mnt/D$ disown me@host:/mnt/D$ logout As for computations that are already running, especially those with GUIs attached, these cannot in all cases be saved. Why the server must be restarted -------------------------------- Last weekend and the weekend before, the LWP homedir server went down unexpectedly. We found that this was because it ran out of memory. Whether this is caused by a memory leak or some misconfiguration, we cannot yet tell. After some measures, it is not consuming memory as quickly any more, but I'm not confident that it will last another full week. (About half of its memory is still free after five days' uptime.) If we reboot it just before Monday however, it 'll stay up for another week. During that week, we will prepare an upgrade of its software, which may well fix the machine. So it is likely that during the weekend of the 24th the server will have to be brought down for maintenance, or at least rebooted again to free up some memory. We apologize for the inconvenience. Kind Regards, Jurjen (for all LWP admins)