Snapshot and restore in Elasticsearch - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this snapshot creation request?

Given the following Elasticsearch snapshot creation request, what will be the response status if the repository exists and is accessible?

Elasticsearch

{
  "repository": "my_backup",
  "snapshot": "snapshot_1",
  "body": {
    "indices": "index1,index2",
    "ignore_unavailable": true,
    "include_global_state": false
  }
}

A Acknowledged: true, Snapshot created successfully

B Error: Repository not found

C Snapshot creation failed due to missing indices

D Timeout error during snapshot creation

💡 Hint

Check if the repository exists and the indices are available.

If the repository exists and indices are available or ignored if unavailable, the snapshot creation will be acknowledged successfully.

❓ Predict Output

intermediate

What does this restore request do?

Consider this Elasticsearch restore request. What will be the effect on the cluster?

Elasticsearch

{
  "repository": "my_backup",
  "snapshot": "snapshot_1",
  "body": {
    "indices": "index1",
    "rename_pattern": "index(\\d+)",
    "rename_replacement": "restored_index$1",
    "include_global_state": false
  }
}

A Restores index1 as restored_index1 without changing cluster settings

B Restores all indices and overwrites cluster settings

C Fails because rename_pattern is invalid

D Restores index1 but keeps the original name

💡 Hint

Look at the rename_pattern and rename_replacement fields.

The restore request renames index1 to restored_index1 and does not include global cluster state, so cluster settings remain unchanged.

🔧 Debug

advanced

Why does this snapshot creation fail with a repository error?

Analyze the following snapshot creation request and identify the cause of the failure.

Elasticsearch

{
  "repository": "backup_repo",
  "snapshot": "snap_2024",
  "body": {
    "indices": "*",
    "ignore_unavailable": false
  }
}

A ignore_unavailable must be true when using '*' wildcard

B The repository 'backup_repo' is not registered or accessible

C The wildcard '*' is invalid for indices

D Snapshot name 'snap_2024' is invalid

💡 Hint

Check repository registration and accessibility.

If the repository is not registered or accessible, snapshot creation fails regardless of indices or options.

❓ Predict Output

advanced

What is the output of this snapshot status request?

Given this request to check snapshot status, what will be the output if the snapshot is currently in progress?

Elasticsearch

GET /_snapshot/my_backup/snapshot_1/_status

A {"snapshots":[{"snapshot":"snapshot_1","state":"SUCCESS"}]}

B {"error":"Snapshot not found"}

C {"snapshots":[{"snapshot":"snapshot_1","state":"IN_PROGRESS"}]}

D {"snapshots":[]}

💡 Hint

Consider the snapshot lifecycle states.

The snapshot status API returns the current state of the snapshot. If it is running, the state is IN_PROGRESS.

🧠 Conceptual

expert

Which option correctly describes the behavior of restoring snapshots with include_global_state set to true?

When restoring a snapshot with include_global_state set to true, what happens?

A Global state is ignored and only indices are restored

B Only index data is restored; cluster settings remain unchanged

C Restoring fails if global state is included

D Cluster settings, templates, and persistent metadata from the snapshot are restored, potentially overwriting current cluster state

💡 Hint

Think about what global state means in Elasticsearch snapshots.

Setting include_global_state to true restores cluster-wide settings and metadata from the snapshot, which can overwrite current cluster state.

Practice

1. What is the main purpose of taking a snapshot in Elasticsearch?

easy

A. To save a backup of your data for recovery later

B. To speed up search queries

C. To delete old indexes automatically

D. To create new indexes from templates

Solution

1. Step 1: Understand snapshot purpose

   A snapshot in Elasticsearch is used to save a backup of your data at a point in time.

2. Step 2: Compare options

   Options B, C, and D describe other Elasticsearch features, not snapshot backup.

3. Final Answer:

   To save a backup of your data for recovery later -> Option A

4. Quick Check:

   Snapshot = Backup [OK]

Hint: Snapshots save data backups for recovery [OK]

Common Mistakes:

• Confusing snapshots with index templates
• Thinking snapshots speed up searches
• Assuming snapshots delete data

2. Which of the following is the correct syntax to create a snapshot repository in Elasticsearch?

easy

A. POST /_snapshot/my_backup {"type": "fs", "settings": {"location": "/mount/backups"}}

B. PUT /_snapshot/my_backup {"type": "fs", "settings": {"location": "/mount/backups"}}

C. GET /_snapshot/my_backup {"type": "fs", "settings": {"location": "/mount/backups"}}

D. DELETE /_snapshot/my_backup {"type": "fs", "settings": {"location": "/mount/backups"}}

Solution

1. Step 1: Identify correct HTTP method for creating repository

   Creating a snapshot repository uses the PUT method to define or update it.

2. Step 2: Check other methods

   POST is for creating snapshots, GET is for retrieving info, DELETE is for removing repositories.

3. Final Answer:

   PUT /_snapshot/my_backup {"type": "fs", "settings": {"location": "/mount/backups"}} -> Option B

4. Quick Check:

   Repository creation = PUT [OK]

Hint: Use PUT to create or update snapshot repositories [OK]

Common Mistakes:

• Using POST instead of PUT for repository creation
• Confusing GET with creation commands
• Trying to delete instead of create repository

3. Given this snapshot restore request:

POST /_snapshot/my_backup/snapshot_1/_restore
{
  "indices": "index1,index2",
  "rename_pattern": "index(.*)",
  "rename_replacement": "restored_index$1"
}

What will be the name of the restored index originally named index2?

medium

A. restored_index2

B. restored_index_index2

C. index2

D. index_restored2

Solution

1. Step 1: Understand rename_pattern and rename_replacement

   The pattern "index(.*)" captures the part after "index". The replacement "restored_index$1" adds "restored_index" plus the captured part.

2. Step 2: Apply to index2

   For "index2", the captured part is "2", so the new name is "restored_index2".

3. Final Answer:

   restored_index2 -> Option A

4. Quick Check:

   Rename pattern + replacement = restored_index2 [OK]

Hint: Captured group $1 appends after renamed prefix [OK]

Common Mistakes:

• Ignoring rename_pattern and keeping original name
• Adding extra 'index' in the replacement
• Misplacing the captured group in new name

4. You try to restore a snapshot but get an error: repository_missing_exception. What is the most likely cause?

medium

A. The snapshot name is incorrect

B. The cluster is running an incompatible Elasticsearch version

C. The snapshot repository does not exist or is not registered

D. The indices in the snapshot are corrupted

Solution

1. Step 1: Understand repository_missing_exception meaning

   This error means Elasticsearch cannot find the snapshot repository to access snapshots.

2. Step 2: Check other options

   Snapshot name errors cause different exceptions; corrupted indices cause restore failures but not repository missing; version mismatch causes other errors.

3. Final Answer:

   The snapshot repository does not exist or is not registered -> Option C

4. Quick Check:

   repository_missing_exception = missing repository [OK]

Hint: Check repository registration if repository_missing_exception occurs [OK]

Common Mistakes:

• Assuming snapshot name typo causes repository_missing_exception
• Blaming corrupted indices for repository errors
• Ignoring repository setup before restore

5. You want to restore only specific indexes from a snapshot but rename them to avoid conflicts. Which JSON snippet correctly does this during restore?

{
  "indices": "logs-2023,metrics-2023",
  "rename_pattern": "(.*)-2023",
  "rename_replacement": "$1-restore"
}

hard

A. Restores only logs-restore and metrics-restore indexes from snapshot

B. Restores logs-2023 and metrics-2023 with original names

C. Restores all indexes in snapshot renamed with -restore suffix

D. Restores logs-2023 and metrics-2023 as logs-restore and metrics-restore

Solution

1. Step 1: Analyze indices and rename_pattern

   Indices "logs-2023" and "metrics-2023" match the pattern "(.*)-2023" capturing "logs" and "metrics".

2. Step 2: Apply rename_replacement

   Replacement "$1-restore" changes names to "logs-restore" and "metrics-restore".

3. Step 3: Confirm only specified indices restored

   Only indices listed in "indices" are restored, renamed as specified.

4. Final Answer:

   Restores logs-2023 and metrics-2023 as logs-restore and metrics-restore -> Option D

5. Quick Check:

   Indices filtered + renamed correctly = Restores logs-2023 and metrics-2023 as logs-restore and metrics-restore [OK]

Hint: Use indices + rename_pattern/replacement to rename on restore [OK]

Common Mistakes:

• Restoring all snapshot indices ignoring filter
• Not using rename_pattern correctly
• Expecting renamed indexes to exist before restore