Cloud Digital Leader Why Cloud Technology Can Transform Business Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  Use a single non-preemptible VM to ensure completion.

  Why it's wrong here

  A single non-preemptible n1-standard-8 VM guarantees uninterrupted execution because Google Cloud will not reclaim it, but you pay the full on-demand price for the entire duration, often 60-80% more than preemptible pricing. Since this nightly batch job is inherently fault-tolerant and has a tight completion window, choosing an expensive, always-on VM directly contradicts the requirement for cost optimization, even though it technically ensures the job finishes.

• ✗

  Use the same VM but as preemptible; if preempted, restart the job from scratch.

  Why it's wrong here

  Preemptible VMs can be terminated by Compute Engine at any time with only a 30-second shutdown notice, regardless of how much progress has been made. Without checkpointing, any preemption forces the job to restart all computation from scratch; if preemption occurs after 40 minutes of the 90-minute window, the total time becomes 40 + 90 = 130 minutes, exceeding the deadline. This option lacks the resumability needed to make preemptible instances viable for a time-bound batch workload.

• ✓

  Split the workload across 4 preemptible n1-standard-8 VMs with checkpointing.

  Why this is correct

  Splitting the workload across 4 preemptible n1-standard-8 VMs reduces per-VM runtime to roughly one-quarter of the original, assuming the batch is parallelizable, which helps fit within the 90-minute window. Each VM writes checkpoints of its progress to a shared persistent location (e.g., Cloud Storage or a persistent disk); if any VM is preempted, a replacement VM can be launched and resume from the last saved state, losing only minutes of work rather than the entire job. Preemptible VMs cost about 20-40% of standard VMs, so the solution is highly cost-effective while still being resilient to preemption via checkpointing.

• ✗

  Use a single preemptible VM with persistent disk snapshots every 10 minutes.

  Why it's wrong here

  Persistent disk snapshots capture the entire disk state, but taking one every 10 minutes injects heavy I/O overhead and snapshot creation can take time for large disks, eating into the 90-minute window. Worse, recovery requires creating a new disk from the snapshot and booting a new VM, which is not near-instantaneous; you'd also lose up to 10 minutes of work, and any in-memory state would be lost entirely. Application-level checkpointing (e.g., streaming intermediate results to durable object storage) is far more granular and faster to resume than disk snapshots, making this option both slower and less reliable.

Go deeper

Related to this question