The start scheduler workflow creates a Google VM that acts as a GT scheduler. The workflow is associated to a single worker pool with a static IP and Google Persistent disk. These two ensure that every time a VM is started the Static IP and scheduler's work directory are preserved.

To send jobs from GTISE to the scheduler just enter the scheduler's IP address in GTISE --> File --> Options --> Run Distributed. To get the IP address please go to the corresponding job directory in the PW IDE and open the start_scheduler/sched.out file, as shown in the image below. However, note that this process is only required once as the IP address will always be the same for a given scheduler pool.

• Executor Pools: The scheduler sends packets to the GT executor pools. Please select one or more executor pools. If more than one executor pool is selected the smart pool selector algorithm will be used to distribute the load among the different executor pools. This algorithm minimizes the number iddle cores and executor VMs.

• Cloud platform

• GT user name: Linux user that starts the scheduler service and user in the /etc/systemd/system/gtdistd.service.d/override.conf file.

• GT version

• License servers: <port1>@<host1>:<port2>@<host2>. On Windows, the separator is a semicolon.

• Activate job summary service: Select whether to active the job summary service in the scheduler's properties file.

• Core demand sensing cycle duration [s]: Specify the cycle duration for sensing the core demand. Core demand is sensed every cycle.
• Over demand satisfaction fraction [0,1]: Fraction of the core over demand to satisfy every cycle. If the value 1 is selected all the core over demand is satisfied in just one cycle. Select less than 1 if the packet runtime is much smaller than VM startup time.

To connect to the scheduler VM through a tunnel follow the instruction in this section:

1. Add the SSH public keys of the client to /pw/workflows/start_scheduler/authorized_keys before starting the workflow. Make sure the keys are in the right format (see instructions below).
2. Run the workflow and wait for the scheduler to start. Watch the streaming logs under /pw/jobs/job_number/start_scheduler/sched.out
3. Start the SSH tunnel in the client host (see instructions bellow).
4. Introduce 0.0.0.0 (localhost) as the IP of the scheduler VM in the Network Distributed configuration in GTISE.

CORRECT FORMAT

ssh-rsa AAAAB3Nza_LONG_PUBLIC_KEY_JhhEGu60qQ== user@machine

Keys generated with Putty must be converted to the format above from the format below:

WRONG FORMAT

---- BEGIN SSH2 PUBLIC KEY ----
Comment: "rsa-key-20210630"
AAAAB3Nza_LONG_PUBLIC_KEY_JhhEGu60qQ==
---- END SSH2 PUBLIC KEY ----

Run this command in your local terminal to start the tunnel

ssh -N \
    -L 0.0.0.0:8979:127.0.0.1:8979 \
    -L 0.0.0.0:8970:127.0.0.1:8970 \
    tunnel@scheduler_vm_ip

Add the information to the tunnels section below before opening your session.