Backup

4.3 Given a scenario, implement workstation backup and recovery methods.

📘CompTIA A+ Core 2 (220-1202)

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When managing computers and IT systems, backing up data is essential. A backup is a copy of files, folders, or entire systems that you can restore if the original data is lost, corrupted, or deleted. There are several methods of backup, each with its own purpose.

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1. Full Backup

• Definition: A full backup copies all selected data from a system every time the backup runs.
• Example in IT: You have a folder on a workstation called ProjectFiles. A full backup copies every file in ProjectFiles every time the backup is scheduled.
• Pros:
  • Everything is backed up, so restoring is fast and simple.
  • Easy to manage because there’s only one backup set.
• Cons:
  • Takes more storage space.
  • Slower to perform because all data is copied every time.
• Use case: Often used for weekly backups of important servers or user data.

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2. Incremental Backup

• Definition: An incremental backup only copies files that have changed since the last backup, whether that last backup was full or incremental.
• Example in IT:
  • Monday: Full backup of ProjectFiles.
  • Tuesday: Only files changed since Monday are backed up.
  • Wednesday: Only files changed since Tuesday are backed up.
• Pros:
  • Faster than a full backup.
  • Requires less storage because only changes are saved.
• Cons:
  • Restoration can be slower, because you need the last full backup plus all incremental backups to restore completely.
  • If one incremental backup is missing or corrupted, restoring can fail.
• Use case: Daily backups of files that change frequently, like user documents or database logs.

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3. Differential Backup

• Definition: A differential backup copies all files that have changed since the last full backup.
• Example in IT:
  • Monday: Full backup of ProjectFiles.
  • Tuesday: Backup of all changes since Monday.
  • Wednesday: Backup of all changes since Monday (includes Tuesday’s changes too).
• Pros:
  • Faster than full backups, but slower than incremental.
  • Restoration is faster than incremental because you only need the last full backup + last differential backup.
• Cons:
  • Backup size grows each day until the next full backup.
• Use case: Mid-week backups of critical workstations, balancing speed and storage efficiency.

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4. Synthetic Full Backup

• Definition: A synthetic full backup is a full backup created from the last full backup and subsequent incremental backups, without needing to copy all data from the workstation again.
• Example in IT:
  • Monday: Full backup of ProjectFiles.
  • Tuesday & Wednesday: Incremental backups of changes.
  • Thursday: The system combines Monday’s full backup + Tuesday & Wednesday incrementals into a new full backup on the backup server.
• Pros:
  • Restores quickly like a full backup.
  • Reduces network usage because workstations don’t need to send all data again.
• Cons:
  • Needs a backup system/server that can merge data.
• Use case: Large organizations where daily full backups over the network are impractical.

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Quick Comparison Table

Backup Type	What it Does	Storage Needs	Restore Speed	Example Use
Full	Copies all data	High	Fast	Weekly backup of all workstation data
Incremental	Copies changes since last backup	Low	Slow	Daily backup of documents or logs
Differential	Copies changes since last full backup	Medium	Medium	Mid-week backup of important files
Synthetic Full	Creates full backup from full + incrementals	Medium	Fast	Enterprise backup systems with limited network bandwidth

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Key Exam Tips

1. Remember the difference between incremental and differential:
   • Incremental: changes since last backup.
   • Differential: changes since last full backup.
2. Synthetic full looks like a full backup but is created without copying all data again.
3. Think in terms of storage, speed, and restore time—these are common exam scenarios.
4. Backup types are often used together in a schedule (e.g., full on Sunday, incremental daily, synthetic full on Friday).