Differenze

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--- oph:cluster:jobs [2023/08/10 23:54] – carlo.cintolesi@unibo.it
+++ oph:cluster:jobs [2024/11/18 09:08] (versione attuale) – diego.zuccato@unibo.it
@@ Linea 10: / Linea 10: @@
 To better enforce the fair use of the frontend, the memory (RAM) usage is limited to 1GB per user.
 ====== Run a Job ======
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 The job script is ideally divided into three sections:
-  * The header, consisting of commented text in which information and notes useful to the user but ignored by the system are given (the syntax of the comments is #text-for-user...);
+  * The header, consisting of commented text in which information and notes useful to the user but ignored by the system are given (the syntax of the comments is ''#text-for-user...'');
-  * The Slurm settings, in which instructions for launching the actual job are specified (the syntax of the instructions is #SLURM --option);
+  * The Slurm settings, in which instructions for launching the actual job are specified (the syntax of the instructions is ''#SLURM --option'');
   * The module loading and code execution, the structure of which varies according to the particular software each user is using.
@@ Linea 105: / Linea 107: @@
 To allocate the resource request in the job script by the WorkLoad Manager, the command must be executed:
-  sbatch runParallel.sh [other parameters]
+  sbatch --time hh:mm:ss runParallel.sh [other parameters]
+<WRAP center round info>
+Estimating the value to use for ''--time'' is possibly the hardest part of the request. Please **do not** always use the maximum allowed time. Using a shorter estimate usually means your job will run before others that are requesting the maximum (backfill scheduling).
+</WRAP>
+<WRAP center round tip>
+''--nodes'' can also be a range.
+While ''--nodes=2 --ntasks=56'' **always** asks for 2 nodes even if the job would run on a single 112-vCPUs node (leading to longer queue times), ''--nodes=1-4 --ntasks=56'' would happily use the bigger node, if available, or up to 4 half-nodes from mtx[00-15].
+</WRAP>
 For the management of running jobs, please refer to section "Job Management".
+===== 'Interactive' jobs =====
+Sometimes you have to run some heavy tasks (unsuitable for the frontend) that require interactivity. For example to compile a complex program that requires you to answer some questions, or to create a container.
+You have to first request a node allocation, either by sbatch (as above, possibly with 'dummy' payload, like a ''sleep 7200'' for a 2h duration) or by:
+  salloc -N 1 --cpus-per-task=... --time=... --mem=... --constraint=blade
+salloc will pause while waiting for the requested resources, so be prepared. It also tells you the value for $JOBID to be used in the following steps.
+Then you can connect your terminal to the running job via:
+  srun --pty --overlap --jobid $JOBID bash
+that gives you a new shell on the first allocated node for $JOBID (just like SSH-ing a node with the resources you asked for).
+Once you're done, remember to call:
+  scancel $JOBID
+to release resources for other users.
 ===== Job Management =====