🔹 Backup & Storage Techniques

📌 1. What is Backup?

👉 Definition: Copy of data stored safely for recovery if data is lost, corrupted, or destroyed.
👉 Purpose: Protect data & ensure business continuity.

📌 2. Types of Backups

🟢 A. Full Backup

What: Complete copy of all data.
✅ Pros: Easy restore (just one file), very reliable.
❌ Cons: Slow, uses lots of storage.
📌 Use: First backup / when data changes a lot.

🟡 B. Incremental Backup

What: Backs up only changes since last backup (full or incremental).
✅ Pros: Fast, small storage needed.
❌ Cons: Restore is slow (need full + all incrementals).
📌 Use: Daily/frequent backups for fast-changing data.

🔵 C. Differential Backup

What: Backs up all changes since last full backup.
✅ Pros: Restore faster than incremental (only full + last differential).
❌ Cons: Larger than incremental, slower than it for daily backups.
📌 Use: Weekly backups / balance between storage & restore speed.

📌 3. Quick Comparison

Feature	Full Backup	Incremental	Differential
Data Backed	Entire dataset	Changes since last backup	Changes since last full
Backup Speed	Slow	Fast	Medium
Storage Needed	High	Low	Medium
Restore Speed	Fast	Slow	Medium

📌 4. Key Takeaways (Easy Memory Triggers)

Full = Big + Easy Restore
Incremental = Small + Hard Restore
Differential = Middle Way

✅ One-Liner to Remember:
Full = everything, Incremental = since last backup, Differential = since last full backup.

🔹 Recovery Strategies for Data Protection

1. What is Data Recovery?

Process of restoring lost/corrupted data.
Goal: Minimize downtime + ensure business continuity.

2. Main Recovery Strategies

A. Backup & Restore

Recover from stored backups.
✅ Cheap, simple
❌ Slow for large data

B. Disaster Recovery (DR)

Big Plan for IT systems after disaster.
Needs DR site + DR Plan.
Ex: Secondary Data Center, Cloud DR.

C. High Availability (HA)

Systems always up & running.
Uses redundant servers, load balancing, failover.
Ex: Clustered DB auto-switches to backup.

D. Replication

Copies data to another location.
Synchronous: Real-time copy.
Asynchronous: Slight delay.
✅ Minimal data loss
❌ Costly

E. RAID (Redundant Array of Independent Disks)

Spreads data across disks.
RAID 1: Mirroring (safe).
RAID 5: Striping + parity (balance).
RAID 6: Double parity (safer).

F. Cloud Recovery

Store backups/replicas in cloud.
✅ Scalable, anywhere access
❌ Needs internet

G. Virtualization-Based Recovery

Use virtual machines (VMs) for fast restore.
✅ Quick, flexible
Ex: Crash → restore as VM.

3. Key Metrics (Very Important for Exams)

RPO (Recovery Point Objective): Max data loss allowed.
- Ex: RPO = 1 hr → backups every hour.
RTO (Recovery Time Objective): Max time to restore system.
- Ex: RTO = 4 hrs → system must be up in 4 hrs.

4. Steps in Recovery Plan

Risk Assessment (find threats).
Data Prioritization (critical vs normal).
Backup Strategy (Full, Incremental, Differential).
Recovery Testing (test plan regularly).
Monitoring (check systems continuously).

5. Common Tools

Backup: Acronis, Veeam.
Cloud: AWS, Azure, Google Cloud.
DR Tools: Zerto, VMware SRM.

6. Quick Tips (for revision)

Always keep offsite backups.
Test recovery plans regularly.
Use encryption for backups.
Remember: RPO = data loss limit, RTO = downtime limit.

👉 For exams: Write 2–3 strategies + RPO/RTO definitions + one example = full marks.

🔹 Backup Strategies (MCQs)

What is a full backup?
A. Only changed files
B. Complete copy of all selected data
C. Changes since last backup
D. Real-time backup
Answer: B
Which backup requires the most storage space?
A. Incremental
B. Differential
C. Full
D. Snapshot
Answer: C
An incremental backup saves:
A. All files regardless of changes
B. Changes since the last full backup
C. Changes since the last backup of any type
D. Files created after schedule started
Answer: C
What is a differential backup?
A. All data regardless of changes
B. Changes since the last incremental backup
C. Changes since the last full backup
D. Real-time continuous backup
Answer: C
Fastest type of backup to create:
A. Full
B. Incremental
C. Differential
D. Real-time
Answer: B
Restoration requiring all previous backups:
A. Full
B. Incremental
C. Differential
D. Snapshot
Answer: B
Best for minimizing storage during daily backups:
A. Full
B. Incremental
C. Differential
D. Cloud
Answer: B
Restoration from differential backup requires:
A. Only latest differential
B. Last full + latest differential
C. All incremental backups
D. Original dataset
Answer: B
Main disadvantage of incremental backup:
A. High storage
B. Slow backup
C. Time-consuming restoration
D. High processing needs
Answer: C
Most suitable for complete system recovery:
A. Full
B. Incremental
C. Differential
D. Selective
Answer: A
Incremental backups depend on:
A. Only the latest incremental backup
B. Last full + all subsequent incremental backups
C. Latest full + differential
D. Only initial full backup
Answer: B
Backup type that grows in size as more changes occur since the last full backup:
A. Full
B. Incremental
C. Differential
D. Real-time
Answer: C
Advantage of a full backup over other types:
A. Faster backup creation
B. Minimal storage needed
C. Simplified restoration
D. Real-time support
Answer: C
Best backup for daily use with minimal data changes:
A. Full
B. Incremental
C. Differential
D. Mirrored
Answer: B
How many backups needed to restore data with a differential strategy?
A. One (latest differential)
B. Two (full + latest differential)
C. All differential backups
D. None, since it stores all changes
Answer: B
Primary disadvantage of differential vs incremental backup:
A. Higher storage usage
B. Slower restoration
C. Dependence on previous backups
D. Complex backup creation
Answer: A
Commonly used as the first step in a backup schedule:
A. Full
B. Incremental
C. Differential
D. Synthetic
Answer: A
If a file is modified multiple times, when is it backed up in incremental backup?
A. Every time modified
B. During the next incremental backup
C. Next full backup only
D. Only if rules match
Answer: B

🔹 Data Recovery & High Availability (MCQs)

Primary goal of data recovery:
A. Minimize downtime & restore data
B. Increase storage
C. Encrypt information
D. Prevent unauthorized access
Answer: A
Strategy ensuring systems remain operational during failures:
A. Backup & Restore
B. Disaster Recovery
C. High Availability
D. RAID
Answer: C
Real-time copies of data in another location:
A. Backup & Restore
B. Replication
C. RAID
D. Virtualization-based recovery
Answer: B
RAID stands for:
A. Redundant Array of Independent Disks
B. Rapid Access to Important Data
C. Recovery Array for Integrated Data
D. Real-time Automated Info Duplication
Answer: A
Purpose of Disaster Recovery Plan (DRP):
A. Encrypt data
B. Define restoration steps after disaster
C. Speed up backups
D. Monitor performance
Answer: B
Synchronous replication means:
A. Backups at scheduled intervals
B. Copies data in real-time without delay
C. Prioritizes recovery speed over accuracy
D. Uses incremental backups to save space
Answer: B
RTO (Recovery Time Objective) is:
A. Max time to restore after failure
B. Time needed for a full backup
C. Acceptable data loss
D. Interval between backups
Answer: A
RAID level known for mirroring:
A. RAID 0
B. RAID 1
C. RAID 5
D. RAID 6
Answer: B
Key disadvantage of cloud-based recovery:
A. High cost
B. Dependency on internet connectivity
C. Cannot scale
D. No automation
Answer: B
Recovery strategy using virtual machines:
A. Backup & Restore
B. High Availability
C. Virtualization-based recovery
D. Disaster Recovery
Answer: C
RPO (Recovery Point Objective) refers to:
A. Max time allowed to recover data
B. Acceptable data loss
C. Interval between backups
D. System maintenance duration
Answer: B
RAID providing striping + parity:
A. RAID 0
B. RAID 1
C. RAID 5
D. RAID 10
Answer: C
High Availability is achieved through:
A. Regular full backups
B. Replication & failover systems
C. Disaster recovery sites
D. Incremental backups
Answer: B
Common tool for disaster recovery in cloud:
A. RAID Controller
B. VMware SRM
C. Bacula
D. ZFS Backup
Answer: B
Primary advantage of replication vs backups:
A. Less storage needed
B. Real-time data availability
C. Reduces need for DR planning
D. Eliminates offsite storage
Answer: B
NOT a key component of a disaster recovery plan:
A. Risk Assessment
B. Data Encryption
C. Communication Plan
D. Recovery Testing
Answer: B
Virtualization-based recovery enables rapid restoration using:
A. Pre-configured VMs
B. High-speed internet
C. Incremental schedules
D. Cloud replication
Answer: A
Fastest access to data during failure is provided by:
A. Incremental Backups
B. RAID
C. Synchronous Replication
D. Differential Backups
Answer: C

✅ Tip: Use these MCQs for exam prep, training, and IT skill-building. Backup & Recovery concepts are vital for database admins, system engineers, and cloud professionals.

Quick Notes on Data Backup and Recovery​