Google ACE Persistent Disk Practice Question
A company wants to run a stateful application on Compute Engine with persistent storage that can be attached to another instance in case of failure. Which storage option should they use?
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
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Persistent Disk
Persistent Disk (PD) is a network-attached block storage that can be detached and reattached to another VM in the same zone. Option C is correct. Option A (Filestore) is a file storage service, not block storage; Option B (Cloud Storage bucket) is object storage; Option D (Local SSD) is ephemeral and tied to the instance.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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Filestore
Why it's wrong here
Filestore offers managed NFS file shares that can be mounted by Compute Engine instances over the network, but it does not provide a raw block device. Stateful applications typically expect a block-level volume that can be formatted, partitioned, and attached directly to an instance; Filestore presents a POSIX file system over NFS, not a block device. While it can store data, it is not suitable for applications that require a dedicated, attached block device with features like boot disks or volume-level snapshots. Thus, Filestore is wrong for a stateful application on Compute Engine.
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Cloud Storage bucket
Why it's wrong here
Cloud Storage buckets are object storage accessed via HTTP/JSON APIs, not block storage. You cannot attach a Cloud Storage bucket as a block device or format it with a filesystem; even when used with tools like gcsfuse, it remains object storage with different consistency and performance characteristics. A stateful application that expects to read/write directly to an attached disk would not function correctly with Cloud Storage, as instance disks must be block devices. Therefore, Cloud Storage bucket is incorrect.
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Persistent Disk
Why this is correct
Persistent Disk is durable, network-attached block storage that you can attach to a Compute Engine instance like a physical disk. It survives instance stops and can be detached from one instance and reattached to another, enabling stateful failover. Persistent Disk also supports snapshots, resizing, and zonal or regional replication, making it the appropriate choice for a stateful application. For these reasons, Persistent Disk is the correct answer.
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Local SSD
Why it's wrong here
Local SSDs are physically attached to the host server and provide extremely high IOPS, but their data is ephemeral and exists only for the lifetime of the instance. If the instance is stopped, terminated, or suffers a hardware failure, all data on a Local SSD is permanently lost. Since a stateful application must preserve data across shutdowns and failovers, Local SSD cannot meet the durability and reattachment requirements. Therefore, Local SSD is incorrect for this use case.
Go deeper
Related to this question
Learn chapter
Google Cloud Platform Overview
Key term
Cloud storage
Cloud storage is a service that lets you save data on remote servers accessed over the internet instead of on your computer's hard drive.
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.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ACE 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 ACE exam.