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Currently, the nmpost cluster is a mix of Torque/Moab nmpost{001..090} and HTCondor nmpost{091..120} devhost{001..002}.  Eventually we would like to replace Torque/Moab with Slurm as we think it can do most, if not all, of what Torque/Moab does but is free, is being activly developed, and seems more commonly used these days than Torque/Moab.

We upgraded to Torque-6/Moab-9 in 2018 and thus started having to pay for Torque/Moab.  This was done because Torque-6 understood cgroups and NUMA nodes (although it doesn't handle NUMA nodes how krowe would like), and Torque-6 was no longer compatible with the free scheduler Maui, forcing us to purchase the Moab scheduler.  Since then we have leveraged a couple of things Moab can do that Maui never could like increasing the number of jobs the scheduler looks ahead to schedule, which allows Moab to start reserving space for pending vlass jobs on vlasstest nodes.  This is not a critical requirement.  Largely the win was with cgroups for resource separation and NUMA nodes to double the number of interactive jobs available.  Both of which only required Torque-6 which in turn required Moab-9 which in turn we had to pay for.  See what they did there?  You can read more about it at https://staff.nrao.edu/wiki/bin/view/DMS/SCGTorque6Moab9Presentation

I did look at openpbs which seems to be the free version of PBS Pro maintained by Altair Engineering.  I have found it lacking in a few important things.  it doesn't support a working directory like Torque does with -d or -w, and has no PAM module allowing users to login if they have an active job which would make nodescheduler very hard to implement.  So I don't think openpbs is a suitable replacement for Torque/Moab.

Once nmpost is transitioned we can look at doing cvpost with all the lessons learned in nmpost.  Before cvpost is transitioned we should tell CV users about the coming transition and possibly them use nmpost for testing.

To Do

Prep

  • Done: upgrade testpost-master to RHEL7 so it can run Slurm 122408
  • Done: upgrade nmpost-master to RHEL7 so it can run Slurm 122408
  • Done: Look at upgrading to the latest version of Slurm


Work

  • DONE: Port nodeextendjob to Slurm scontrol update jobid=974 timelimit=+7-0:0:0
  • DONE: Port nodesfree to Slurm
  • DONE: Port nodereboot to Slurm scontrol ASAP reboot reason=testing testpost001
  • DONE: Create a subset of testpost cluster that only runs Slurm for admins to test.
    • Done: Install Slurmctld on testpost-serv-1, testpost-master, and OS image
    • Done: install Slurm reaper on OS image (RHEL-7.8.1.3)
    • Done: Make the new testpost-master a Slurm submit host
  • Done: Create a small subset of nmpost cluster that only runs Slurm for users to test.
    • Done: Install Slurmctld on nmpost-serv-1, nmpost-master, herapost-master, and OS image
    • Done: install Slurm reaper on OS image (RHEL-7.8.1.3)
    • Done: Make the new nmpost-master a Slurm submit host
    • Done: Make the new, disked herapost-master a Slurm submit host.
    • Done: Need at least 2 nmpost nodes for testing: batch/interactive, vlass/vlasstest
      • done: test nodescheduler
      • done: test mpicasa single-node, multi-node.  Both without -n nor -machinefile
  • Identify stake-holders (E.g. operations, VLASS, DAs, sci-staff, SSA, HERA, observers, ALMA, CV) and give them the chance to test Slurm and provide opinions
    • nrao-scg, cchandle, emomjian, bsvoboda, jott, lsjouwer, jmarvil, akimball, dmedlin, mmcclear
    • Should include for next message: jtobin,
  • implement useful opinions
    • Done: for MPI jobs we should either create hardware ssh keys so users can launch MPI worker processes like they currently do in Torque (with mpiexec or mpirun) or, compile Slurm with PMIx to work with OpenMPI3 or compile OpenMPI with the libpmi that Slurm creates.  I expect changing mpicasa to use OpenMPI3/PMIx instead of its current OpenMPI version will be difficult so it might be easier to just add hardware ssh keys.  This makes me sad because that was one of the things I was hoping to stop doing with Slurm.  sigh.  Actually, this may not be needed.  mpicasa figures things out from the Slurm environment and doesn't need a -n or a machinefile.  I will test all this without hardware ssh keys.
    • Done: Figure out why cgroups for nodescheduler jobs aren't being removed.
    • Done: Make heranodescheduler and and heranodesfree and herascancel.
    • Done: Document that the submit program will not be available with Slurm.
    • Done: How can a user get a report of what was requested and used for the job like '#PBS -m e' does in Torque?  SOLUTION: accounting.
    • Done: Update the cluster-nmpost stow package to be Slurm-aware (txt 136692)
      • done: Alter /etc/slurm/epilog to use nodescheduler out of /opt/local/ instead of /users/krowe on nmpost-serv-1
        • cd /opt/services/diskless_boot/RHEL-7.8.1.5/nmpost
        • edit root/etc/slurm/epilog
    • Done: vncserver doesn't work with Slurm from an interactive session using srun --mem=8G --pty bash -l.  I get a popup window reading Call to lnusertemp failed (temporary directories full?)  I also see this in the log in ~/.vnc Error: cannot create directory "/run/user/5213/ksocket-krowe": No such file or directory
      • Unsetting XDG_RUNTIME_DIR then starting vncserver allows me to connect via vncviewer successfully.  I am not aware of anyone that will actually be affected by this because the nm-#### users use nodescheduler and ssh so for them /run/user/<UID> will exist, and I doubt we have any users that currently use qsub -I other than me.  So probably the best thing for now is just to document this and move on.
    • Done: jobs are being restarted after a node reboot. I thouhgt I had that disabled but apparently not. SOLUTION: JobRequeue=0
    • Done: There is a newer version (21.x) It might be simple to upgreade.  I will test on the testpost cluster.
    • Done: MailProg=/usr/bin/smail  This produces more information in the end email message,  Not as much as Torque though.
    • Done: Change to TaskPlugin=affinity,cgroup in accordance with recommendation in https://slurm.schedmd.com/slurm.conf.html
    • Done: Do another pass on the documentation https://info.nrao.edu/computing/guide/cluster-processing
    • Done: Publish new documentation https://info.nrao.edu/computing/guide/cluster-processing
    • Done: Try commenting out PrologFlag=x11 thus setting PrologFlag=none.  nodescheduler doesn't need any prolog flags set.  PrologFlag=contain doesn't seem to be needed by reaper.
      • If I comment out PrologFlag line, then jobs only get the .batch step not the .batch and .extern steps in sstat.
      • If PrologFlag=Alloc then jobs only get the .batch step not the .batch and .extern steps in sstat.
      • If PrologFlag=Contain then jobs get both the .batch and .extern steps in sstat.
      • If PrologFlag=X11 then jobs get both the .batch and .extern steps in sstat.
      • I don't know that we need any PrologFlag set so comment it out until we need it.
    • Skip: cgropus are not being removed when jobs end.  E.g. nmpost035 has uid_1429, uid_25654, and uid_5572 in /sys/fs/cgroup/memory/slurm and all of those jobs have ended.
      •  This is not a critical problem, but more of an annoyance.  It does sometimes set the node state to drain because of Reason=Kill task failed
      • This has been a recurring problem since they introduced cgroup support back around version 17.  Sadly, upgrading to version 21 didn't fix the problem.
      • done: A common suggestion is to increase UnkillableStepTimeout=120 or more.  I have set this and will see if it helps.
      • As of Mar. 1, 2022, after some reboots, there are no extraneous cgroups on nmpost{035..039}.  Let's see if it stays that way.
      • May 3, 2022 krowe: I see some on nmpost036.  uid_5684 from Mar. 11 and uid_9326 from Mar.21.  Oh well.  I have noted this as an issue in our Slurm install docs on the wiki.
    • Skip: The sstat -j <jobid> command produces blanks both at NRAO and CHTC.
      • See  https://bugs.schedmd.com/show_bug.cgi?id=12405
      • I think this is a result of an update to sstat.  The man page needs to be updated.  The example shows the following.
        • sstat --format=AveCPU,AvePages,AveRSS,AveVMSize,JobID -j 11
      • The man page should either add the -a option or use 11.batch
    • Document and perhaps script ways to see if your job is swapping.  Slurm doesn't seem to track this which is really unfortunate.
    • Try job_container/tmpfs Does it remove the need for the reaper script?  Does it break things?  Seems like it could be a good idea.  Like how HTCondor works.  But when I try it I get this in the slurmd.log 

      • [2022-03-01T15:00:09.965] error: container_p_join: open failed for /var/tmp/slurm/1975/.ns: No such file or directory

      • Is this because the first thing job_container/tmpfs does is try to umount /dev/shm, which is nuts, and /dev/shm seems to alway have a lldpad.state file?  On a non-diskless node, like rastan, I can start lldpad, remove the file with lldpad -d, then stop the service.  Still, the idea of umounting /dev/shm is rediculous.  Isn't there a bunch of other stuff that will use /dev/shm and prevent the kernel from umounting it?
      • I made testpost-master an execution host and jobs run on it.  So perhaps job_container doesn't work with diskless nodes.
      • I filed a ticket https://bugs.schedmd.com/show_bug.cgi?id=14113
      • Turns out it was our fault.  The initial ramdisk apparently has the file /dev/shm/lldpad.state because systemd/selinux/whatever. Then the rhel-readonly unit makes this a bindmounted file which then prevents Slurm from using job_contaier/tmpfs. I think it is easier to just unmount this file than try to alter the initial ramdisk.
      • This can also use /tmp on the local disk (i.e. NVMe) instead of a shared ramdisk for /tmp.  That should be good.  But it also means the nodes will need local storage.  All of our nodes do have some sort of local storage. Currently (May 26, 2022) nodes only have a 2GB tmpfs for /tmp so we woulnd't need a lot of disk for a /tmp for each job using job_container/tmpfs and of course /dev/shm doesn't use disk space.
        • nmpost{001..010} /dev/sda1 558GB used for swap
        • nmpost{011..020} /dev/sda1 894GB used for swap
        • nmpost{021..040} : /dev/sda1 558GB used for swap
        • nmpost{041..060}: /dev/sda1 894GB used for swap
        • nmpost{061..090{: /dev/sda1 447GB used for swap /dev/sda2 447GB used for /mnt/scratch
        • nmpost{091..120}: /dev/sda1 447GB used for swap /dev/nvme0n1p1 3.5TB used for /mnt/condor
        • herapost{001..003}: /dev/sda 558GB unused
        • herapost{004..006}: /dev/sda1 558GB used for swap (supposedly temporary)
        • herapost007: /dev/sda 558GB unused
        • herapost008: /dev/sda1 447GB used for swap (supposedly temporary)
        • herapost009: /dev/sda1 238GB used for swap 209GB unused
        • herapost010: /dev/sda1 447GB used for swap (supposedly temporary)
        • herapost{011.14}: /dev/sda1 931GB used for swap (supposedly temporary)
      • So we don't need to use job_container/tmpfs.  It is good to know that it works.  We can plan on doing it later when we have local space available on each node.  If I submit a job to a node that isn't defined in job_container.conf, I get an error.  But I can use something like /var/tmp/slurm as the default then things work pretty much as they do without job_container except that files in /tmp and /dev/shm are cleaned up when the job is over without needing the reaper script.  Then if we want to override this and put /tmp on an actual block device we can do that with NodeName.  Here is an example.

        • AutoBasePath=true

          BasePath=/var/tmp/slurm

          NodeName=testpost001 BasePath=/mnt/condor/slurm

  • Enumerate all needs that SSA still has for Torque.

    • casa-imaging-pipeline.sh.vlass.*.* quicklook /lustre/aoc/cluster/pipeline/vlass_prod/spool/quicklook/VLASS2.2* 31gb

    • casa-pipeline.sh /lustre/aoc/cluster/pipeline/dsoc-prod/spool/ 48gb
    • casa-calibration-pipeline.sh.vlass.*.* /lustre/aoc/cluster/pipeline/vlass_prod/spool/se_calibration/VLASS2.1*
    • create-component-list.sh.vlass.*.* /lustre/aoc/cluster/pipeline/vlass_prod/spool/se_continuum_imaging/VLASS2.1*
    • DeliveryJob.dsoc-prod.* /lustre/aoc/cluster/pipeline/dsoc-prod/spool/ 48gb
    • data-fetcher.sh.dsoc-prod.* /lustre/aoc/cluster/pipeline/dsoc-prod/spool/ 16gb
    • ingest.dsoc-dev.* /lustre/aoc/cluster/pipeline/dsoc-dev/tmp/ProductLocatorWorkflowStartupTask_runVlbaReingestionWorkflow_*
    • ingest.dsoc-test.* /lustre/aoc/cluster/pipeline/dsoc-test/tmp/ProductLocatorWorkflowStartupTask_runVlbaReingestionWorkflow_*
    • run-solr-indexer.sh.dsoc-test.* /lustre/aoc/cluster/pipeline/dsoc-test/tmp/ProductLocatorWorkflowStartupTask_runSolrReindexCalForProject_*
  • Figure out how many nodes may need to remain running Torque/Moab, how many can become Slurm, and how many are in question.
    • Need to remain Torque until Aug. 2023
      • I am thinking SSA needs about 30 cores of 48GB each which is at least 3 512GB nodes in both the batch and vlass queues.  Daniel and Jim think 5 nodes would be sufficient for SSA.
    • Can become Slurm:
      • We often have about 40 interactive jobs running, so at least 20 nodes could easily become Slurm nodes without much fuss.  In fact we could start migrating interactive nodes to Slurm before the big switch.
    • In question
      • jott vlasstest jobs
      • jtobin vlasstest jobs
      • VLASS nodes nmpost{061..090} are some or all of these moving to HTCondor?
  • Set a date to transition to Slurm.  This will probably be a partial transition where only a few nodes remain for SSA.  Preferably this will be before our 2022 Moab license expires on Sep. 30, 2022.
    • We usually start the process of renewing Moab in July and receive the new license in August.
    • SIW 2022 ends May 26, 2022 and uses 14 nodes.
    • Summer Students start May 17, 2022.  Don't know when they end.  It's at least 4 nodes.
    • Data Reduction Workshop (CASA Class) 2022 starts Oct. 2, 2022 and ends Oct. 20, 2022 and uses 16 nodes.
  • Send email to all parties, especially the nm observer accounts, about the change.
    • Note that the submit script (which Lorant still uses) will be going away.
    • Make a draft message now with references to documentation and leave variables for dates.


Launch

RHEL-7.8.1.5 defaults to not starting pbs_mom because of PBS_ARGS="-h" in RHEL-7.8.1.5/nmpost/root/etc/sysconfig/pbs_mom but then is overridden by PBS_ARGS="" in etc/sysconfig/pbs_mom in snapshots.  It is looking like we won't be able to do a clean transfer.  We will have to keep some Torque/Moab nodes around for a while (SSA workflows, etc).  So we may want to be able to switch nodes between Torque/Moab and Slurm easily.  Here is how https://staff.nrao.edu/wiki/bin/view/NM/NmpostRHEL7#Set_schedulers_off_by_default

The instructions below assume all nodes (nmpost{001..090}) but it is likely you will want to change that to just the subset of noides that you are transitioning to Slurm.

  • On zia, configure DHCP to boot all nmpost nodes to RHEL-7.8.1.5
  • Switch remaining nmpost nodes from Torque/Moab to Slurm on nmpost-serv-1
    • Change to the snapshot directory
      • cd /opt/services/diskless_boot/RHEL-7.8.1.5/nmpost/snapshot
    • Enable slurmd to start on boot
      • for x in nmpost{001..090}* ; do echo 'SLURMD_OPTIONS="--conf-server nmpost-serv-1"' > ${x}/etc/sysconfig/slurmd ; done
      • for x in nmpost{001..090}* ; do  echo '/etc/sysconfig/slurmd' >> ${x}/files ; done
    • Disable Torque from starting on boot
      •  for x in nmpost{001..090}* ; do  echo 'PBS_ARGS="-h"' > ${x}/etc/sysconfig/pbs_mom ; done
    • Reboot each node you modified
  • On zia, switch nodescheduler, nodeextendjob, nodesfree from Torque to Slurm
    • Change to the stow directory
      • cd /home/local/Linux/rhel7/x86_64/stow
    • Alter the email that is sent.  The default version of nodescheduler is now slurm instead of torque.
      • #edit cluster/share/cluster/cluster_job_*.sh and change 'nodescheduler-slurm' to 'nodescheduler' in the slurm email functions
      • #edit cluster/share/cluster/cluster_job_*.sh and change 'nodescheduler' to 'nodescheduler-torque' in the torque email functions
    • Change the symlinks from pointing to the Torque versions to the Slurm versions.  Don't unstow the package as that could kill jobs.
      • (cd cluster/bin ; rm -f nodescheduler ; ln -s nodescheduler-slurm nodescheduler)
      • (cd cluster/bin ; rm -f nodescheduler-test ; ln -s nodescheduler-test-slurm nodescheduler-test)
      • (cd cluster/bin ; rm -f nodeextendjob ; ln -s nodeextendjob-slurm nodeextendjob)
      • (cd cluster/bin ; rm -f nodesfree ; ln -s nodesfree-slurm nodesfree)
  • Add nodes to Slurm scheduler
    • On nmpost-serv-1, edit /etc/slurm/slurm.conf and uncomment and modify NodeName lines.  Each node can only be in one NodeName line.
    • On nmpost-serv-1, edit /etc/slurm/slurm.conf and modify PartitionName lines.  There cannot be more than one PartitionName line per partition.
    • On nmpost-serv-1 restart slurmctld with systemctl restart slurmctld
    • On nmpost-master restart slurmd with systemctl restart slurmd
  • On info.nrao.edu, remove the bold notes about Slurm in the docs

Test

  • Use nodescheduler to reserve a node.  Try with various options.
  • Submit a Slurm job
    • srun sleep 27 
  • Submit a Torque/Moab job
    • echo "sleep 27" | qsub


Later Clean

Much later, when we are sure we don't want certain nodes to ever run Torque/Moab again, we can do the following.  This is a rough idea of what needs to be done.  I would suggesting making this part of a new OS image like RHEL-7.8.1.6 or later.

  • Remove nodefindfphantoms
  • Remove cancelmanyjobs
  • Remove nodereboot and associated cron job on servers
  • Remove Torque reaper
  • Uninstall Torque from OS image.
  • Uninstall Torque from nmpost and testpost servers
  • Remove snapshot/*/etc/ssh/shosts.equiv
  • Remove snapshot/*/etc/ssh/ssh_known_hosts
  • Change to the snapshot directory
    • cd /opt/services/diskless_boot/RHEL-7.8.1.5/nmpost/snapshot
  • Disable Torque from starting on boot
    • for x in nmpost{001..002}* ; do rm -f ${x}/etc/sysconfig/pbs_mom ; done
    • for x in nmpost{001..002}* ; do sed -i '/^\/etc\/ssh\/pbs_mom/d' ${x}/files ; done
    • for x in nmpost{001..002}* ; do sed -i '/^\/etc\/ssh\/shosts.equiv/d' ${x}/files ; done
    • for x in nmpost{001..002}* ; do sed -i '/^\/etc\/ssh\/ssh_known_hosts/d' ${x}/files ; done
    • Remove /opt/services/torque*
    • Remove /etc/profiles.d/torque*
    • Remove /var/spool/torque*
  • Remove pam_pbssimpleauth.so from files in /etc/pam.d in the OS image
  • Remove /usr/lib64/security/pam_pbssimpleauth.* from the OS image

Done


  • DONE: Sort out the various memory settings (ConstrainRAMSpace, ConstrainSwapSpace, AllowedSwapSpace, etc)



References

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