Aura

Server aura.fi.muni.cz is available to FI staff and students for longer or more demanding calculations. Access to the machine is created automatically by FI and PhD students. For study or research purposes, FI staff may grant access to other persons through faculty administration . If you are planning a more extensive use of Aura (several students) for teaching, please contact first unix@fi.muni.cz .

Way of work

We are not currently considering the introduction of a queue system for long-running tasks. It is enough to run long-running processes with a reduced priority (in the range of 10-19, 19 is the lowest). Long-running processes are those that run for more than an hour. To do this, for example, use the command nice ./váš_program . Additionally, you can restrict the program to use only certain processors with the command taskset . Example of starting with minimum priority on the 11th to 15th processor:

nice -n 19 taskset -c 10-14 ./váš_program

You can use the command to change the priority of an already running process renice that can be applied to threads, processes, or process groups (see the command man page). However, keep in mind that a process can run in multiple threads, and changing the priority for a single process can change the priority of only one thread. A list of all threads in my processes, including priority, can be obtained, for example, with the following command:

ps x -Lo pgid,pid,tid,user,nice,tty,time,args

You can perform short-term processes or interactive debugging of your programs with normal priority.

In the event that your process does not comply with the priority limit and uses a large amount of computing power, all of your processes will be set to the lowest priority to prevent other users from being restricted 19. In the event of repeated or more serious violations of this rule, your faculty account may be temporarily suspended.

You may also find the following commands useful for tracking or limiting resource usage:

# monitoring of the memory and CPU usage of your processes
systemd-cgtop /user.slice/user-$UID.slice

# limit available resources
help ulimit
# cap the size of virtual memory to 20000 kB
ulimit -Sv 20000
# cap the amount of total CPU time to seconds
ulimit -St 3600
# cap the number of concurrently running threads/processes
ulimit -Su 100

Specific software

If you need to install libraries or tools for your work, you have (apart from local compilation) several options:

• if they are part of a distribution ( dnf search software-name ), you may request administrator about installation,
• you can make module ,
• as for the Python package, it can also be installed locally using pip/pip3 install --user , or can be used virtualenv .

Disk capacity

Directories are available for temporary data that should be available locally quickly /tmp and /var/tmp on a fast RAID 10 volume. To use this space, save your data in the directory with your login. Unaccessible data ( atime ) are automatically lubricated, u /tmp at the age of several days, u /var/tmp in a number of months (the exact settings can be found in the file /etc/tmpfiles.d/tmp.conf ). Disk quotas do not apply here; however, be considerate of others when using the place.

Hardware configuration

Server Aura now runs on the HP DL980 G7 platform in the configuration:

• 8 eight-core 64-bit Intel Xeon X7560 2.26 GHz processors ( 64 cores in total).
• 448 GiB DDR3 RAM
• Gigabit Ethernet connection
• 8 disks with a capacity of 300 GB and 12 disks with a capacity of 1.8 TB, connected in RAID 10, ie 12 TB of logical capacity