Cloud Digital Leader Google Cloud Products and Services Practice Question
A company runs a high-performance computing (HPC) workload on Compute Engine that requires low-latency, high-throughput scratch storage. The workload is checkpointed every hour. Which TWO storage options should the engineer consider for the scratch storage? (Choose 2)
⚠ Common exam trap
GCDL often tests the misconception that any SSD-backed storage is equally suitable for HPC, ignoring the trade-offs between Local SSD (ephemeral, ultra-low latency) and Persistent Disk SSD (durable, slightly higher latency).
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Persistent Disk (SSD)
Option B (Persistent Disk SSD) is correct because SSD-backed Persistent Disks deliver the high IOPS and throughput needed for low-latency scratch storage while remaining durable and independent of the VM lifecycle, which suits an HPC workload that checkpoints hourly. Option C (Local SSD) is correct because Local SSDs are physically attached NVMe devices offering the lowest latency and highest throughput per instance, making them ideal for scratch data that is regenerated from checkpoints. Option A (Persistent Disk HDD) is not appropriate because HDD-backed disks have much lower IOPS and higher latency than SSDs. Option D (Filestore) is a managed NFS file service optimized for shared file access rather than the highest-throughput local scratch storage. Option E (Cloud Storage) is an object store accessed over the network, so it cannot provide the low-latency, high-throughput block-level scratch performance required.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Persistent Disk (HDD)
Why it's wrong here
HDD Persistent Disk is a network-attached block storage product built on spinning media. It offers significantly lower random IOPS and higher latency than SSD alternatives, making it inadequate for the high-throughput, low-latency I/O patterns typical of HPC scratch workloads. It is better suited for cost-sensitive bulk storage where sequential reads dominate and performance is not critical.
- ✓
Persistent Disk (SSD)
Why this is correct
Persistent Disk (SSD) is a durable, network-attached block storage service that provides consistent, low-latency performance and survives instance termination. For HPC scratch, it can be used when data must persist across restarts or preemption, allowing successful checkpointing and restart without data loss. Its performance scales with provisioned size, and it supports multiple per-instance volumes to meet aggregate throughput needs.
- ✓
Local SSD
Why this is correct
Local SSD is a block device physically attached to the host server, delivering the absolute lowest latency and highest IOPS available on Compute Engine. It is ideal for ephemeral HPC scratch where only the fastest possible storage is acceptable, but data is lost when the VM stops or migrates. Best practice is to pair it with periodic checkpoints to Persistent Disk or Cloud Storage to preserve important intermediate results.
- ✗
Filestore
Why it's wrong here
Filestore is a fully managed, network-attached NAS service that uses the NFS protocol. Because all I/O goes over the network and through the file system protocol stack, it has inherently higher latency and lower random I/O throughput than block-based local SSD or Persistent Disk. While convenient for shared datasets, it is not suited for HPC scratch workloads that require very fast, low-latency reads and writes.
- ✗
Cloud Storage
Why it's wrong here
Cloud Storage is an object storage system accessed via HTTP, not a block storage interface. It offers high durability, unlimited scalability, and low cost per GB, but it has high latency and no consistent random I/O performance, making it impossible to use as low-latency scratch space. It is appropriate for storing checkpoints, results, and archives, but not for active HPC scratch files.
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Related to this question
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Key term
Persistent Disk
Persistent Disk is a durable, high-performance block storage service for Google Cloud virtual machines that retains data even after the VM is shut down or deleted.
Key term
Service
A service is a software component or system that performs a specific function and is available to be used by other programs or users over a network.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Google Cloud exam blueprint
This GCDL practice question is part of Courseiva's free Google Cloud certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the GCDL exam.