PCDE Memorystore Standard Tier Practice Question
You are managing a Memorystore for Redis instance that is part of a high-traffic e-commerce application. The instance uses the volatile-lru eviction policy and has persistence disabled. You need to improve data durability without losing the ability to evict keys with TTL. You also want to ensure that the instance can automatically recover from a zonal failure. Which TWO actions should you take? (Choose TWO.)
⚠ Common exam trap
Candidates often confuse cross-region replicas with the Standard Tier's zonal replication. Standard Tier provides automatic failover within a region across zones, but not across regions. Also, manual exports via Cloud Scheduler are not a substitute for built-in persistence when durability is the goal.
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
✓
Enable RDB persistence by setting the persistence mode.
(Enable RDB persistence) improves data durability by taking periodic snapshots without interfering with the volatile-lru eviction policy, which only evicts keys with TTL. Option D (Standard Tier with replication) provides automatic failover across zones within a region, ensuring recovery from a zonal failure. Option A only reduces eviction frequency but does not address durability or zonal failover. Option C is incorrect because Memorystore does not support native cross-region replicas. Option E uses manual exports, which do not enable automatic recovery and are not equivalent to persistence.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the maxmemory setting to reduce eviction frequency.
Why it's wrong here
Increasing maxmemory reduces eviction frequency but does not improve durability or provide zonal failover.
- ✓
Enable RDB persistence by setting the persistence mode.
Why this is correct
Correct. Enabling RDB persistence saves periodic snapshots, improving durability without affecting the volatile-lru eviction policy.
- ✗
Configure a cross-region replica to provide failover in another region.
Why it's wrong here
Incorrect. Memorystore does not natively support cross-region replicas; failover within a region uses Standard Tier.
- ✓
Create a standard tier instance with replication enabled for automatic failover.
Why this is correct
Correct. Standard Tier with replication provides automatic failover across zones, enabling recovery from a zonal failure.
- ✗
Set up a Cloud Scheduler job to export the instance to Cloud Storage every hour.
Why it's wrong here
Incorrect. Cloud Scheduler exports are manual backups that do not provide automatic recovery from zonal failures.
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Same concept, more angles
6 more ways this is tested on PCDE
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is using Memorystore for Redis and wants to ensure data persistence in case of a failure. What is the recommended approach?
easy- A.Configure a standard tier instance, which provides automatic persistence.
- B.Enable RDB persistence and configure the backup interval.
- ✓ C.Use Cloud Storage snapshots (export) or configure cross-region replication.
- D.Enable AOF persistence in Memorystore settings.
Why C: Memorystore for Redis does not support native persistence (AOF/RDB). For data durability, the recommendation is to use scheduled Cloud Storage snapshots or cross-region replication.
Variation 2. You are running a Memorystore for Redis instance with persistence disabled. The application requires high availability and data durability after a zone failure. What is the most cost-effective approach?
hard- A.Use a Basic tier instance and schedule periodic exports to Cloud Storage.
- B.Enable persistence using the AOF or RDB configuration in Memorystore.
- ✓ C.Use a Standard tier instance with cross-zone replication.
- D.Deploy a Redis Cluster across multiple regions using Memorystore.
Why C: Standard tier Memorystore for Redis instances provide cross-zone replication by default, ensuring automatic failover and data durability in the event of a zone failure. This meets the high availability and data durability requirements without the need for manual exports or complex multi-region setups, making it the most cost-effective solution.
Variation 3. A company uses Memorystore for Redis with Standard Tier (replication) and needs to ensure data durability in case of a zone failure. They also need to scale read throughput beyond a single instance. What should they do?
hard- A.Create a cross-region replica and use it for read traffic.
- B.Upgrade to a larger machine type with more memory.
- C.Enable persistence using AOF and configure a backup schedule.
- ✓ D.Migrate to Redis Cluster with 3+ shards.
Why D: Memorystore for Redis Standard Tier provides cross-zone replication for high availability. To scale read throughput, they can use Redis Cluster (which shards data across multiple shards) or create read replicas. However, Memorystore does not support read replicas for Redis; instead, Redis Cluster provides horizontal scalability and high availability. Upgrading to a larger instance scales vertically but not read throughput horizontally. Persistence is not natively supported in Memorystore.
Variation 4. A company uses Memorystore for Redis and wants to ensure data is preserved in case of a node failure. They cannot afford any data loss. What should they do?
medium- A.Increase the maxmemory setting to avoid eviction
- ✓ B.Enable AOF persistence on the Redis instance
- C.Use active cross-region replication to a replica instance
- D.Schedule periodic backups to Cloud Storage using export
Why B: To guarantee no data loss during a node failure, Memorystore for Redis should have persistence enabled. Standard Tier instances support both RDB and AOF persistence. AOF persistence, especially with an fsync policy of 'always' or 'everysec', ensures that writes are durably stored, minimizing data loss to at most one second. Periodic exports to Cloud Storage are backups that occur at scheduled intervals, so any data written between the last export and the failure would be lost, violating the zero-data-loss requirement. Increasing maxmemory only controls eviction, not durability. Cross-region replication provides high availability but does not persist data to disk on its own and can lose recently written data due to replication lag.
Variation 5. A Cloud Memorystore for Redis instance needs to ensure data is not lost during a maintenance event. The team decides to enable persistence. However, Memorystore does not support Redis persistence. What is the recommended alternative?
easy- ✓ A.Use the Standard tier with replication and take regular snapshots to Cloud Storage using a scheduled script.
- B.Migrate to Cloud SQL for MySQL and use its backup feature.
- C.Enable AOF persistence in Memorystore.
- D.Increase the maxmemory setting and rely on the allkeys-lru eviction policy.
Why A: Cloud Memorystore for Redis does not support native Redis persistence (RDB or AOF). To prevent data loss during maintenance events, the recommended alternative is to use the Standard tier (which provides replication and automatic failover) and supplement it with scheduled snapshots exported to Cloud Storage. This approach ensures a durable backup outside the Redis instance that can be restored if needed.
Variation 6. Your Memorystore for Redis instance is used as a session store for a web application. You need to ensure that session data is not lost during a node failure. What should you do?
medium- A.Use a Basic Tier instance with a large maxmemory setting.
- B.Configure the instance as Standard Tier (with replication) and schedule periodic exports to Cloud Storage.
- C.Enable persistence by setting the 'persistence' parameter to 'rdb' in the instance configuration.
- ✓ D.Enable AOF persistence in the Memorystore instance.
Why D: Memorystore for Redis supports persistence via RDB snapshotting or AOF (Append-Only File). For minimal data loss during a node failure, AOF persistence is recommended because it logs every write operation, allowing recovery with only a few seconds of data loss (depending on fsync settings). Standard Tier with replication provides high availability but does not persist data to disk, so a full zone failure can cause data loss. Periodic exports to Cloud Storage have gaps between exports, leading to data loss of up to the export interval. Therefore, enabling AOF persistence is the best approach to prevent data loss during a node failure.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCDE 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 PCDE exam.