You are here: Home › Support › Time allocations

What is a time allocation?

By belonging to a time allocation (a CAC) PDC's queuing system (EASY) can set the priority of one user's job relative to other jobs submitted by other people. Time allocations can be personal or shared, but they always sets the maximum number of node-hours members of a time allocation are entitled to run jobs for on a computer every month.

Time allocations

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:

  1. Prioritize your submitted jobs compared to other people's jobs.
  2. 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:

  1. A CAC states the number of node hours members of that CAC are entitled to run jobs for every month.
  2. A CAC states which users belong to that CAC and are allowed to use the CAC's time for running jobs.
  3. Every CAC has an expiration date.
  4. 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, that job will automatically be submitted in the slow lane (if one exists on the particular system).

Slow lane

On most PDC clusters there is a slow lane. Jobs that are submitted when:

  1. the user doesn't belong to a CAC on that comptuer/cluster or,
  2. the time allocation that the user belongs to has already used all its time for that particular month, or
  3. when you deliberately submit a job to the slowlane (for instance using the free.userName time allocation).
Jobs in the slow lane will automatically get the lowest priority. This means that your job will only be allowed to run if no one else wants to run a job at the moment. So, make sure that you have a time allocation when you submit jobs at PDC.

Test time allocations

Test time allocations often have names such as: 
 ta.yourUsername

Test time allocations are intended for individuals who are only testing PDC's resources, for instance when you start using PDC's resources and want to test if your programs work on our computers. A test time allocation gives you 50 node-hours per month for a limited time of six months. The test time allocation is personal, i.e. you are the only person that can submit jobs and use these 50 node-hours every month.

Principal investigators

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.

Application forms

Depending on how much time you think that you need to run jobs for there are different ways of applying for more time.

 

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.