Storage: CLF-C02 study notes and practice questions
What to know about Storage for the CLF-C02 exam, from the Cloud Technology and Services domain (34% of the exam guide), then 3 free questions to test it. Part of the CLF-C02 study guide.
Storage questions describe how data is used and ask for the matching service or storage class.
The services
Service
Type
Use for
Amazon S3
Object storage, virtually unlimited
Files, backups, data lakes, static websites
Amazon EBS
Block storage volumes for one EC2 instance in one AZ
Boot drives and databases on EC2
EC2 instance store
Temporary block storage on the host
Scratch data that can be lost when the instance stops
Amazon EFS
Shared file system for Linux
Many instances sharing the same files
Amazon FSx
Managed file systems (Windows File Server, Lustre, NetApp ONTAP, OpenZFS)
Windows file shares or high-performance computing
AWS Storage Gateway
Hybrid storage
Giving on-premises applications access to cloud storage
AWS Backup
Central, policy-based backups
Backing up many AWS services on a schedule
AWS Elastic Disaster Recovery
Server replication for recovery
Fast recovery of servers into AWS
S3 storage classes
Class
For data that is
S3 Standard
Accessed often
S3 Intelligent-Tiering
Accessed unpredictably; moves objects between tiers automatically
S3 Standard-IA
Accessed less than monthly but needed quickly
S3 One Zone-IA
Infrequent and easy to re-create (stored in one AZ)
S3 Glacier Instant Retrieval
Archive that still needs millisecond access
S3 Glacier Flexible Retrieval
Archive; minutes to hours to retrieve
S3 Glacier Deep Archive
Long-term archive; lowest cost, hours to retrieve
S3 Lifecycle rules move objects to cheaper classes or delete them after a set time.
Other S3 features
Versioning keeps old versions of objects; S3 Object Lock stops objects being deleted or changed for a retention period (compliance mode applies even to the root user); replication copies objects to another bucket or Region.
Common traps
EBS for sharing files between instances. Use EFS (Linux) or FSx for Windows File Server.
Instance store for important data. It is lost when the instance stops.
Glacier for data needed instantly. Only Glacier Instant Retrieval returns data in milliseconds.
A law firm must keep scanned client files for ten years.
Files are opened often in their first month, rarely after that, and almost never after one year, when a wait of several hours to retrieve one is acceptable.
What should the firm do to lower storage costs with the least ongoing effort?
Choose one answer.
AA. Keep every file in S3 Standard for ten years, so access stays fast
BB. S3 Lifecycle rules: Standard-IA after 30 days, Glacier Deep Archive after one year
CC. Copy the files to Amazon EBS volumes attached to an EC2 instance
DD. Store all files in S3 One Zone-IA from the day they are uploaded
Show the answer and explanation
Answer: B
A. Wrong: S3 Standard gives fast access but costs more per GB than colder storage classes. Keeping rarely opened files there for ten years wastes money.
B. Right: Lifecycle rules move files to cheaper classes automatically, with no manual work. Standard-IA suits files opened less often after the first month, and Glacier Deep Archive is the lowest-cost class, with standard retrieval typically within 12 hours. Learn more: Storage classes for Amazon S3 (opens in a new tab)
C. Wrong: EBS volumes are block storage attached to a server, so the firm would need to run and manage that server. This adds ongoing effort rather than reducing it.
D. Wrong: Each retrieval from One Zone-IA carries a per-GB fee, and the frequent early access in the first month would add many of these charges.
Explanation
Lifecycle rules let the firm move files to cheaper classes at the right times with no manual work. Standard-IA fits the drop-off in access after the first month, and Glacier Deep Archive fits files retrieved rarely, when a wait of hours is acceptable. Keeping everything in Standard or using One Zone-IA from day one both ignore the access pattern.
A company wants one place to define backup plans that run on a schedule for its Amazon EBS volumes, Amazon RDS databases, Amazon DynamoDB tables and Amazon EFS file systems, and to keep each backup for a set retention period.
Which service should it use?
Choose one answer.
AA. AWS Backup, which runs scheduled backup plans across many resource types
BB. AWS Storage Gateway, which connects on-premises applications to cloud storage
CC. AWS DataSync, which copies files between storage locations
DD. Amazon S3 Lifecycle, which moves and expires objects in S3 buckets
B. Wrong: Storage Gateway provides hybrid storage access for on-premises applications. It is not a policy-based backup service for these AWS resources.
C. Wrong: DataSync moves data between storage systems, such as on-premises and AWS. It does not apply backup plans with retention periods across these resource types.
D. Wrong: S3 Lifecycle manages objects inside S3 buckets only. It cannot back up EBS volumes, RDS databases, DynamoDB tables or EFS file systems.
Explanation
AWS Backup is the central service for scheduled, policy-based backups across many AWS resource types, with retention you set. Storage Gateway, DataSync and S3 Lifecycle each cover a different job, such as hybrid access, data transfer or object management in S3.
A financial firm must keep trade records in Amazon S3 unchanged for seven years, as its regulator requires.
No one at the firm, including its AWS administrators, may be able to delete or overwrite a record during that period.
Which S3 feature meets this requirement?
Choose one answer.
AA. S3 Versioning, which keeps earlier versions of each object
BB. A bucket policy that denies delete requests to all users
CC. S3 Object Lock in compliance mode, with a seven-year retention period
DD. An S3 Lifecycle rule that moves records to Glacier Flexible Retrieval
Show the answer and explanation
Answer: C
A. Wrong: Versioning keeps every version of an object, so an overwrite does not destroy the earlier data. A user with permission can still delete a version, so the regulator's rule is not met.
B. Wrong: Anyone who can edit the bucket policy can remove the deny statement, so administrators could still delete records. A policy is not a lock that holds for the full period.
C. Right: In compliance mode, no user, including the root user, can overwrite or delete a protected object version, and the retention period cannot be shortened. That holds for the full seven years. Learn more: Locking objects with Object Lock (opens in a new tab)
D. Wrong: Lifecycle rules change the storage class and can expire objects on a schedule. They do not stop a user with permission from deleting or overwriting a record.
Explanation
S3 Object Lock in compliance mode is the only option that stops every user, including administrators and the root user, from changing a protected object until its retention date. Versioning and bucket policies can be undone by someone with permission, and lifecycle rules manage cost or expiry rather than protection.
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