# Octopus Maintenance

## Slurm

Status of slurm (as of 202512)

```
sinfo
workers*     up   infinite      8   idle octopus[03,05-11]
allnodes     up   infinite      3  alloc tux[06,08-09]
allnodes     up   infinite     11   idle octopus[02-03,05-11],tux[05,07]
tux          up   infinite      3  alloc tux[06,08-09]
tux          up   infinite      2   idle tux[05,07]
1tbmem       up   infinite      1   idle octopus02
headnode     up   infinite      1   idle octopus01
highmem      up   infinite      2   idle octopus[02,11]
386mem       up   infinite      6   idle octopus[03,06-10]
lowmem       up   infinite      7   idle octopus[03,05-10]
```

```
sinfo -R
squeue
```

we have draining nodes, but no jobs running on them

Reviving draining node (as root)

```
scontrol update NodeName=octopus05 State=DOWN Reason="undraining"
scontrol update NodeName=octopus05 State=RESUME
scontrol show node octopus05
```

Kill time can lead to drain state

```
scontrol show config | grep kill
UnkillableStepProgram   = (null)
UnkillableStepTimeout   = 60 sec
```

check valid configuration with 'slurmd -C' and update nodes with

```
scontrol reconfigure
```

## Password management

So we create a script that can deploy files from octopus01 (head node). Unfortunately ids in passwd do no match, so we can't copy those yet.

See /etc/nodes for script and ssh files, sudoers (etc)

Basically the root user can copy across.

## Execute binaries on mounted devices

To avoid './scratch/script.sh: Permission denied' on 'device_file':

- 'sudo bash'
- 'ls /scratch -l' to check where '/scratch' is
- 'vim /etc/fstab'
- replace 'noexec' with 'exec' for 'device_file'
- 'mount -o remount [device_file]' to remount the partition with its new configuration.

Some notes:

root@tux09:~# mkdir -p /var/lib/nfs/statd
root@tux09:~# systemctl enable rpcbind
Synchronizing state of rpcbind.service with SysV service script with /lib/systemd/systemd-sysv-install.
Executing: /lib/systemd/systemd-sysv-install enable rpcbind
root@tux09:~# systemctl list-unit-files | grep -E 'rpc-statd.service'
rpc-statd.service                                                         static          -

network-online.target
x-systemd.device-timeout=
10.0.0.110:/export/3T  /mnt/3T  nfs nofail,x-systemd.automount,x-systemd.requires=network-online.target,x-systemd.device-timeout=10 0 0


## Installation of 'munge' and 'slurm' on a new node

Current nodes in the pool have:

```shell
munge --version
    munge-0.5.13 (2017-09-26)
sbatch --version
    slurm-wlm 18.08.5-2
```

To install 'munge', go to 'octopus01' and run:

```shell
guix package -i munge@0.5.14 -p /export/octopus01/guix-profiles/slurm

systemctl status munge # to check if the service is running and where its service file is
```

We need to setup the rights for 'munge':

```shell
sudo bash

addgroup -gid 900 munge
adduser -uid 900 -gid 900 --disabled-password munge

sed 's,/home/munge:/bin/bash,/var/lib/munge:/usr/sbin/nologin,g' /etc/passwd -i

mkdir -p /var/lib/munge
chown munge:munge /var/lib/munge/

mkdir -p /etc/munge
# copy 'munge.key' (from a working node) to '/etc/munge/munge.key'
chown -R munge:munge /etc/munge

mkdir -p /run/munge
chown munge:munge /run/munge

mkdir -p /var/log/munge
chown munge:munge /var/log/munge

mkdir -p /var/run/munge # todo: not sure why it needs such a folder
chown munge:munge /var/run/munge

# copy 'munge.service' (from a working node) to '/etc/systemd/system/munge.service'

systemctl daemon-reload
systemctl enable munge
systemctl start munge
systemctl status munge
```

To test the new installation, go to 'octopus01' and then:

```shell
munge -n | ssh tux08 /export/octopus01/guix-profiles/slurm-2-link/bin/unmunge
```

If you get 'STATUS: Rewound credential (16)', it means that there is a difference between the encoding and decoding times. To fix it, go into the new machine and fix the time with

```shell
sudo date MMDDhhmmYYYY.ss
```

To install 'slurm', go to 'octopus01' and run:

```shell
guix package -i slurm@18.08.9 -p /export/octopus01/guix-profiles/slurm
```

We need to setup the rights for 'slurm':

```shell
sudo bash

addgroup -gid 901 slurm
adduser -uid 901 -gid 901 --no-create-home --disabled-password slurm

sed 's,/home/slurm:/bin/bash,/var/lib/slurm:/bin/bash,g' /etc/passwd -i

mkdir -p /var/lib/slurm
chown munge:munge /var/lib/slurm/

mkdir -p /etc/slurm
# copy 'slurm.conf' to '/etc/slurm/slurm.conf'
# copy 'cgroup.conf' to '/etc/slurm/cgroup.conf'

chown -R slurm:slurm /etc/slurm

mkdir -p /run/slurm
chown slurm:slurm /run/slurm

mkdir -p /var/log/slurm
chown slurm:slurm /var/log/slurm

# copy 'slurm.service' to '/etc/systemd/system/slurm.service'

/export/octopus01/guix-profiles/slurm-2-link/sbin/slurmd -f /etc/slurm/slurm.conf -C | head -n 1 >> /etc/slurm/slurm.conf # add node configuration information

systemctl daemon-reload
systemctl enable slurm
systemctl start slurm
systemctl status slurm
```

On 'octopus01' (the master):

```shell
sudo bash

# add the new node to '/etc/slurm/slurm.conf'

systemctl restart slurmctld # after editing /etc/slurm/slurm.conf on the master
```


# Removing a node

We are removing o3 so it can become the new head node:

```
scontrol update nodename=octopus03 state=drain reason="removing"
scontrol show node octopus03 | grep State
scontrol update nodename=octopus03 state=down reason="removed"
  State=DOWN+DRAIN ThreadsPerCore=2 TmpDisk=0 Weight=1 Owner=N/A MCS_label=N/A
```