What is a time allocation?
Time allocations are sometimes referred to as CACs, which is an abbreviation of Charge Account Category. Using time allocations on every computer enables us two do two important things:
- Prioritize your submitted jobs compared to other people's jobs.
- Keep track of how much time that is used each month by different users and user groups.
Every user at PDC can belong to several time allocations - at least one for every computer/cluster that you submit jobs on. Time allocations can be personal, or shared between several people. All time allocations (CACs) have at least the following properties:
- A CAC states the number of node hours members of that CAC are entitled to run jobs for every month.
- A CAC states which users belong to that CAC and are allowed to use the CAC's time for running jobs.
- Every CAC has an expiration date.
- A CAC is valid on a particular system/computer, although CACs with the same name can be present on several systems.
If a user does not belong to any time allocation when submitting a job then on most systems the job submission will fail.
Since the test time allocation is so limited - both in time per month for running jobs, and in duration - many projects have applied for more time on a certain computer/cluster. For instance, a professor might apply for a time allocation that will cover the needs for all people in a certain research project.
The person that applied for the time allocation is called the Principal Investigator, PI. The PI, can choose to include others into a time allocation by asking PDC to do so. Every person that is included in a time allocation has to be confirmed by the owner of the time allocation, i.e. the PI. If, you are a new user at PDC it is always good to ask your supervisor/professor if they have a time allocation that you should be included into. To be included into an existing time allocation PDC needs the PI to explicitly ask PDC for this, for instance by sending us an e-mail.
Depending on how much time you think that you need to run jobs for there are different ways of applying for more time. Interested in Zorn? Please read this!
- Small time allocation if you 50 - 5000 core hours per month
Medium time allocation if you need 5000 - 80000 core hours per month (only senior scientists)
- Large time allocation if you need more than 80000 core hours per month (only senior scientists)
Small time allocations are created locally at PDC. Medium and large time allocations are handled on a national level through SNAC (Swedish National Allocations Committee).
Node hours and core hours
At PDC we allocate time on our systems in node hours. SNAC, allocates time in kilocore hours.
Node hours (n) equal core hours (c) divided by the number of cores per node (cpn), i.e:
n = c/cpn
Conversely, core hours equal the number of cores per node times node hours:
c = cpn*n
The queuing systems at PDC uses node hours, and you are charged according to the number of node hours you have requested on a particular system.
Which time allocation do you belong to?
If you are using a computer or system at PDC which is using the queuing system EASY you may check which time allocation you belong to yourself (when logged in on that system).
First, you need to add the queuing system, EASY, module:
module add easy
Then, this commands tells you which time allocations you belong to on that cluster/computer:
cac members yourUsername
To learn all the details of a time allocation execute:
cac examine anyCACname
If the system you are using uses another queuing system you can not get this information yourself. Instead, you need to get that information from PDC.
Acknowledge your SNAC/PDC time allocation
If you have written an article or a poster based on results achieved using computational resources given to you through a SNAC time allocation you might want to acknowledge this contribution. The SNAC committee will check your previous use of given time allocations if you in the future apply for more computation time.