In the reservation confirmation email, reservation identification number Resv ID will be one of the information. Using this number, you can get all the information about the reservation (time of reservation, users of the reservation, assigned resources). Reservations work on the principle that for each reservation a new job queue is created with the name of reservation identification (eg R543.admin).

Users must specify in their job submission scripts that they want to run jobs on reserved resources (#PBS -q R543). Reserved resources can only be used by members of the group for which the reservation was requested.

Overview of the reservation

A list of all reservations can be obtained by command pbs_rstat.


pbs_rstat
[rocky@pbs-rocky ~]$ pbs_rstat
Resv ID    Queue    User     State             Start / Duration / End              
---------------------------------------------------------------------
R1196.rock R1196    korisnik RN          Today 10:17 / 600 / Today 10:27      
R1197.rock R1197    korisnik CO          Today 12:17 / 600 / Today 12:27


The pbs_rstat command provides information about the name of the reservation, the queue used for the reservation, who is the user of the reservation (it shows only the first one in the list, not all users), the state of the reservation (CO - confirmed, RN -running) and the time of the reservation.

Full information about the reservation is obtained by adding -f Resv ID 

pbs_rstat -f
[rocky@pbs-rocky ~]$ pbs_rstat -f R1197
Resv ID: R1197.rocky-server
Reserve_Name = NULL
Reserve_Owner = rocky@pbs-rocky
reserve_state = RESV_CONFIRMED
reserve_substate = 2
reserve_start = Tue Oct 24 12:17:00 2023
reserve_end = Tue Oct 24 12:27:00 2023
reserve_duration = 600
queue = R1197
Resource_List.ncpus = 5
Resource_List.nodect = 1
Resource_List.select = 1:ncpus=5
Resource_List.place = free
Resource_List.walltime = 00:10:00
resv_nodes = (pbs-rocky:ncpus=5)
Authorized_Users = korisnik2@pbs-rocky,rocky@pbs-rocky
server = rocky-server
ctime = Tue Oct 24 10:21:19 2023
mtime = Tue Oct 24 10:21:19 2023
Variable_List = PBS_O_LOGNAME=rocky,PBS_O_HOST=pbs-rocky,PBS_O_MAIL=/var/spool/mail/rocky,PBS_TZID=Europe/Zagreb
reserve_count = 1
partition = pbs-default

The full printout gives the user the most important information, namely how many resources are available and how they were requested. This information is important because the jobs submitted to the reservation queue take the amount of requested resources from the reservation itself. Resources that are not explicitly defined in the job description will be taken from the reservation description, so a job that is not well defined will occupy all the resources requested by the reservation.

Note

Resources not defined in the job description are taken from the reservation description. Thus jobs submitted will occupy all resources requested in the reservation!

Example:
If the reservation of the entire working node is requested, the reservation will be requested with the option:

pbs_reservations projektA  -R 1217 -D 00:10:00 -l select=1:ncpus=128:mem=470GB

128 processor cores and 470GB of memory on one node were requested.
If submitted job is described as:

#PBS -l select=1:ncpus=10
#PBS -q R543

the job will ask for 10 processor cores in the R543 reservation queue, but in addition to the requested 10 cores, it will also get 470GB of RAM because it is defined in the reservation request and not explicitly requested in the job. After that, all the working memory available through the reservation will be taken and no job will start until the first one finishes.

It would be correct to ask for all resources:

#PBS -l select=1:ncpus=10:mem=10GB
#PBS -q R543

The job described in this way would require 10 processor cores and 10GB of memory, so others using that reservation would be left with 118 cores and 460GB of RAM.

Jobs duration

Jobs submitted to the reservation queue do not have a defined maximum duration, but will be terminated as soon as the reservation expires. It is a good practice to pay attention to duration times, and time jobs to finish before the system terminates them.

Consumption via reservation

The reservation itself is not included in the consumption. Therefore, if no use is observed within the first twenty minutes of the reservation, the reservation will be terminated. The consumption of work carried out through the reservation is calculated as well as outside the reservation.

  • No labels