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Nest is a small cluster consisting of twenty 40-core compute servers, a filestore, and a head node. They all run Linux. The compute servers each have two 20-core Intel Cascade Lake CPUs, 192 GB of RAM, and 8TB of local disk.

Nest can only be accessed by sshing into the head node, whose external name is All work is done from there; there is no need to log directly into compute nodes. Nest uses the local Admitto service, so you log in with the same password as on the workstations.

Homespace is on a disk array attached to the head node. The /home filesystem is currently 5TB in size but we have lots of room to grow this if necessary.  It has user quotas which are currently set to 50GB soft limit with a hard limit of 55GB. It is backed up regularly. Backups can be accessed by the IT staff.

/home is shared to all nodes on the cluster's internal network, so your job sees the same home directory wherever it is on the machine. It's important to remember that from a compute job's point of view accessing this directory is extremely slow, especially if all the nodes are trying at once. Compute jobs should always write data to a local disk if possible, and copy it back to /home at the end.

There is also a shared scratch filesystem /sharedscratch in which you will have a directory. These are not backed up. They have a quota restriction of 450GB soft limit and 500GB hard limit, but it is expected that most people will stay well within that amount. They have the same speed issue as /home.

Each node also has a local /scratch filesystem on which the queueing system will create you a directory when you use the node. These filesystems are about 8TB in size with no quota restriction and are the most appropriate place for your jobs to write temporary files during a run. They are local to each node and so considerably faster than the NFS-mounted /home and /sharedscratch. Please clean up files on /scratch when you are done with them; see the queueing documentation for how to find out which node's /scratch to look at. All of the node /scratch directories are accessible under /nodescratch on the head node. The system uses an automounter so the directories only appear when you try to access them. For example to see the /scratch from node node-0-0 you need to type something like 'ls /nodescratch/node-0-0' .

A variety of compilers and libraries are installed. Like most local Linux machines nest has the modules environment to allow you to switch between different compilers and libraries. The default environment is set up with all the available 64-bit compilers and the latest OpenMPI. If you need to change this then use the module avail command to see what the other options are, and edit the version you want into your ~/.bashrc file.

All compute jobs should be run through the queueing system. The queueing system will run each job on a set of free compute nodes, copying the output back to a user-specified file at the end of the job. The queueing system is SLURM; this will be familiar to users of some of the other theory sector clusters, but please note that the available queues are not the same on every machine.

Read the SLURM instructions for instructions on how to use SLURM. For details about nest's partition setup see nest's SLURM config.

System status 

System monitoring page

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