Purpose of This Lesson

This lesson focuses on recognizing the correct storage service or operational response in AWS Certified CloudOps Engineer Associate scenarios involving Amazon Elastic Block Store (EBS), Amazon Elastic File System (EFS), and AWS Storage Gateway.

The key assessment skill is matching the storage requirement—block storage recovery, file sharing, local access, cloud backup, caching, or tape replacement—to the appropriate AWS feature.

Key Concepts

• Amazon EBS provides block storage volumes for EC2 instances. EBS snapshots can be used to create new volumes for data recovery.
• Amazon EBS volume expansion increases the volume capacity, but the operating system’s file system must also be extended before the additional space is usable.
• CloudWatch Agent can collect disk metrics from an EC2 instance. A CloudWatch alarm can notify administrators when disk usage approaches a problematic level.
• Amazon EFS is appropriate for shared file storage requiring POSIX permissions and NFS access from on-premises servers and EC2 instances.
• AWS Storage Gateway connects on-premises environments with AWS storage services through gateway types designed for different access patterns.
• Stored Volume Gateway retains data locally for low-latency access while providing synchronized backup to an offsite AWS location.
• Tape Gateway supports replacing a tape archival system with an AWS-integrated virtual tape approach.
• Volume Gateway caching can be investigated using cache hit percent and cache percent used metrics. Low cache hit percent combined with high cache utilization indicates that the cache disk may need to be enlarged.

Storage Architecture and Operational Context

Recovering a Deleted File from an EBS Volume

If a user deletes data from an EBS volume and a recent snapshot exists, the recovery workflow is:

1. Create a new EBS volume from the snapshot.
2. Attach the new volume to an EC2 instance.
3. Copy the deleted file from the restored volume to the required location.

The snapshot is used to create a separate recovery volume rather than modifying the original volume in place.

Preventing an EBS Volume from Running Out of Space

To detect future disk-capacity problems, install and use the CloudWatch Agent on the EC2 instance to monitor disk metrics. Configure a CloudWatch alarm to alert when usage reaches the chosen threshold.

This addresses monitoring and notification. It does not itself recover deleted data or expand the EBS file system.

Expanding an EBS Volume

Increasing an EBS volume’s capacity does not automatically make the extra capacity visible to applications. The file system must be extended after the volume is enlarged. A scenario that says the volume was increased but the additional space is unavailable is testing this distinction between the block device and the file system.

Choosing EBS sc1 for Infrequent Sequential Access

For a big data application that stores data sequentially and accesses it infrequently, a Cold HDD (sc1) EBS volume is the cost-effective choice identified in this lesson. The access pattern—not simply the fact that the data is large—drives the selection.

Choosing EFS for Shared POSIX File Storage

Use Amazon EFS when shared drives must:

• Support POSIX permissions.
• Use the NFS protocol.
• Be accessible from on-premises servers and EC2 instances.

This requirement is different from attaching a block-oriented EBS volume to an individual EC2 instance.

Choosing a Storage Gateway Type

A Stored Volume Gateway is appropriate when users need low-latency local access to data while maintaining synchronized backup to an offsite location. This fits an office that needs local access to image files and disaster-recovery support.

A Tape Gateway is appropriate when an organization needs to replace a tape archival system.

For iSCSI performance problems in a Volume Gateway, review cache metrics. If the cache hit percent is below 55% and cache percent used is above 95%, create a larger disk for the cache volume and select it in the management console.

Exam- or Assessment-Relevant Takeaways

• Deleted EBS data plus a recent snapshot: create a new volume from the snapshot, attach it, and copy the required file.
• Prevent recurring disk-capacity issues on EC2: use the CloudWatch Agent for disk metrics and a CloudWatch alarm.
• Increased EBS capacity not visible: extend the file system.
• Large, sequential, infrequently accessed data: choose the Cold HDD sc1 volume type.
• POSIX and NFS file sharing across on-premises servers and EC2: choose EFS.
• Low-latency local access with synchronized offsite backup: choose a Stored Volume Gateway.
• Tape archival replacement: choose a Tape Gateway.
• Volume Gateway cache hit below 55% with cache usage above 95%: enlarge the cache disk and select it in the management console.

Tool / Feature Decision Guide

Requirement	Best fit from this lesson	Decisive reason
Recover a deleted file when a recent EBS snapshot exists	New EBS volume from the snapshot	Provides a separate restored copy from which the file can be copied
Alert when an EC2 disk is filling up	CloudWatch Agent plus CloudWatch alarm	Collects disk metrics and triggers notification
Sequential data accessed infrequently	EBS Cold HDD sc1	Matches the stated access pattern and cost requirement
Shared POSIX/NFS file system for on-premises and EC2	Amazon EFS	Provides shared file storage with the required file-access model
Local low-latency access plus synchronized offsite backup	Stored Volume Gateway	Keeps access local while backing up to an offsite location
Replacement for tape archival	Tape Gateway	Designed for the tape-archival use case
Volume Gateway cache is heavily used and has low hit rate	Larger cache disk	Addresses the stated cache-capacity and performance condition

Common Traps / Misconceptions

• Mistaking a larger EBS volume for a completed file-system expansion: The volume can have more block capacity while the file system still exposes the old size.
• Trying to recover a deleted file by relying only on the original volume: When a recent snapshot exists, create a separate volume from it and copy the needed data.
• Choosing EBS for shared NFS/POSIX access: EBS is block storage attached to an instance; the stated shared file requirements point to EFS.
• Confusing Stored Volume Gateway with Tape Gateway: Stored Volume Gateway addresses local access with synchronized backup, while Tape Gateway addresses tape archival replacement.
• Ignoring cache metrics in a Volume Gateway scenario: Low cache hit percent and high cache percent used are signals to consider a larger cache disk.
• Treating storage monitoring as automatic capacity prevention: CloudWatch monitoring and alarms provide visibility and alerts; they do not replace the required storage or file-system operation.

Real-World Engineer / Analyst Notes

• Separate data recovery, capacity monitoring, and capacity expansion when troubleshooting EBS. They require different actions.
• When documenting an EBS expansion, record both the block-volume change and the file-system extension as separate operational steps.
• For shared file requirements, identify the protocol and permission model first. POSIX permissions and NFS are strong indicators that a file service such as EFS is needed.
• For Storage Gateway decisions, determine whether the primary requirement is local low-latency access, cloud-backed storage, or tape replacement.
• Cache metrics should be interpreted together. A low cache hit percent indicates that requests are often not served from cache, while very high cache utilization indicates pressure on the cache disk.

Quick Reference Summary

• EBS snapshot recovery: Snapshot → new EBS volume → attach to EC2 → copy deleted file.
• EBS capacity alerting: CloudWatch Agent disk metrics plus CloudWatch alarm.
• EBS expansion: Increase the volume and extend the file system.
• Infrequent sequential big data: Cold HDD sc1.
• Shared POSIX/NFS storage: EFS.
• Local access with synchronized offsite backup: Stored Volume Gateway.
• Tape archive replacement: Tape Gateway.
• Volume Gateway cache pressure: Cache hit below 55% and cache usage above 95% → create a larger cache disk and select it in the management console.

Flashcards

Q: A user deleted a file from an EBS volume, and a recent snapshot is available. What recovery approach should you use?

A: Create a new EBS volume from the snapshot, attach it to an EC2 instance, and copy the deleted file from the restored volume.

Q: An EC2 instance’s EBS volume repeatedly approaches full capacity. Which monitoring approach should be used?

A: Use the CloudWatch Agent to collect disk metrics and configure a CloudWatch alarm for the relevant usage threshold.

Q: What is the operational trap after increasing an EBS volume’s capacity?

A: The file system may still expose the original size. The file system must be extended before the new capacity is usable.

Q: Which EBS option fits a big data workload that writes sequentially and accesses data infrequently?

A: Cold HDD sc1, because the stated workload favors an inexpensive volume for sequential, infrequent access.

Q: A shared drive must support POSIX permissions and NFS access from both on-premises servers and EC2. Which service should you select?

A: Amazon EFS, because it provides shared file storage with the required POSIX and NFS characteristics.

Q: When would you choose EFS instead of EBS for a storage requirement?

A: Choose EFS when multiple environments need shared file access using NFS and POSIX permissions. EBS is the block-storage option for an EC2 instance rather than the shared file-system choice described here.

Q: An office needs low-latency local access to image files and synchronized backup to an offsite location. Which Storage Gateway configuration fits?

A: Use a Storage Gateway configured as a Stored Volume Gateway, because it supports local access with synchronized offsite backup.

Q: What Storage Gateway type is appropriate for replacing a tape archival system?

A: Tape Gateway.

Q: A Volume Gateway has a cache hit percent below 55% and cache percent used above 95%. What action is indicated?

A: Create a larger disk for the cache volume and select it in the management console.

Q: How do Stored Volume Gateway and Tape Gateway differ in the scenarios covered here?

A: Stored Volume Gateway addresses local low-latency access with synchronized backup, while Tape Gateway addresses replacement of a tape archival system.

Q: Does increasing an EBS volume automatically make the extra space available to applications?

A: No. The underlying volume capacity increases, but the file system must also be extended.

Q: What is the distinction between using a CloudWatch alarm and restoring data from an EBS snapshot?

A: A CloudWatch alarm detects and reports a disk condition, while an EBS snapshot provides a source for creating a recovery volume and copying data.

Practice Questions

Question 1

An EC2 instance runs a big data application that stores information sequentially and accesses it infrequently. The team wants the most cost-effective EBS choice for this pattern. What should they select?

A. Amazon EFS

B. EBS Cold HDD sc1

C. Stored Volume Gateway

D. Tape Gateway

Correct answer: B. EBS Cold HDD sc1

The decisive clues are sequential storage, infrequent access, and cost sensitivity.

Question 2

A file was deleted from an EBS volume. A recent snapshot exists, and the administrator wants to restore only that file without treating the original volume as the recovery workspace. What should the administrator do?

A. Increase the original volume size

B. Configure a Tape Gateway

C. Create a new EBS volume from the snapshot, attach it, and copy the file

D. Install the CloudWatch Agent and wait for an alarm

Correct answer: C. Create a new EBS volume from the snapshot, attach it, and copy the file

The snapshot supplies the recovery point, and the new volume provides access to the prior file state.

Question 3

An organization needs a shared drive accessible by on-premises servers and EC2 instances. The drive must support POSIX permissions and NFS. Which service best fits?

A. Amazon EBS

B. Amazon EFS

C. Tape Gateway

D. EBS Cold HDD sc1

Correct answer: B. Amazon EFS

POSIX permissions, NFS, and shared access identify a file-system requirement suited to EFS rather than instance-oriented block storage.

Question 4

An office requires low-latency access to image files at the local site and synchronized backup to an offsite location for disaster recovery. Which option should be selected?

A. Stored Volume Gateway

B. Tape Gateway

C. EFS only

D. CloudWatch Agent only

Correct answer: A. Stored Volume Gateway

The combination of local access and synchronized offsite backup matches the Stored Volume Gateway scenario.

Question 5

An EBS volume was enlarged, but the operating system still reports the previous amount of usable space. What is the most likely next action?

A. Replace the volume with a Tape Gateway

B. Configure EFS permissions

C. Extend the file system

D. Create a CloudWatch alarm only

Correct answer: C. Extend the file system

Increasing the EBS block volume does not automatically extend the file system that applications use.

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Study guide for choosing and operating Amazon EBS, EFS, and AWS Storage Gateway in AWS Certified CloudOps Engineer Associate scenarios.

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AWS Certified CloudOps Engineer, Amazon EBS, Amazon EFS, AWS Storage Gateway, EBS snapshots, CloudWatch Agent, Volume Gateway, Tape Gateway