ARA-C01 Snowflake Architecture Practice Question
A query is performing poorly due to 'Remote Disk I/O'. The architect notices that the query profile shows a large number of micro-partitions being scanned. The table is already clustered on the filter column. What is the most likely cause of the high Remote Disk I/O?
⚠ Common exam trap
Many test-takers assume clustering solves all performance issues, forgetting that a cold cache forces the warehouse to read from remote storage regardless of table clustering.
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
✓
The warehouse cache is cold or the data exceeds the local cache capacity.
Remote Disk I/O occurs when a Virtual Warehouse must pull data from the Storage layer (S3/Azure/GCP) because it is not available in the local SSD cache. Even if a table is clustered, if the local cache is 'cold' or if the warehouse is too small to hold the working set, the system will constantly fetch data from the remote storage.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The metadata layer is overloaded and cannot provide pruning information.
Why it's wrong here
The metadata layer is highly scalable and rarely becomes a bottleneck for pruning. If the query profile shows many partitions being scanned despite clustering, the issue is more likely related to how the data is being accessed or cached rather than the metadata layer failing to provide the necessary pruning statistics.
- ✓
The warehouse cache is cold or the data exceeds the local cache capacity.
Why this is correct
High Remote Disk I/O is a hallmark of a cold cache or a cache that is too small for the dataset. When the SSDs on the compute nodes don't contain the required micro-partitions, Snowflake must retrieve them from the remote cloud storage, which is significantly slower than reading from the local cache.
- ✗
The table has too many small files, causing metadata bloat.
Why it's wrong here
While many small files can impact performance, Snowflake automatically manages micro-partition size (aiming for 16MB compressed). High Remote Disk I/O specifically refers to the latency of fetching data from remote object storage, which is more directly impacted by cache misses than by the total count of metadata entries.
- ✗
The clustering depth is 1.0, which indicates the table is perfectly clustered.
Why it's wrong here
A clustering depth of 1.0 is the ideal state and would actually minimize the number of micro-partitions scanned. This would reduce Remote Disk I/O because fewer files would need to be fetched. Therefore, a perfectly clustered table cannot be the cause of high I/O; it is the solution to it.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Snowflake exam blueprint
This ARA-C01 practice question is part of Courseiva's free Snowflake 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 ARA-C01 exam.