A scheduled job keeps data between runs on a volume

A job's compute.volumes attaches up to four of your volumes to every run, each at a path, as a sandbox create does: read-write, one run at a time, so each run reads what the last one wrote, or a read-only snapshot copy. In the CLI, runtime jobs create ... --volume <id>:/data, and for a job you already have, runtime jobs update <job> --volume <id>:/data or --no-volumes; in the SDKs' next release. A run that waits for its volume says so with blockedReason volume. See Keep data between runs.