3.4 Backups

Question 1

Backups

Answer 1

• Incredibly important
  –Recover important and valuable data
  –Plan for disaster
• Many different implementations
  –Total amount of data
  –Type of backup
  –Backup media
  –Storage location
  –Backup and recovery software
  –Day of the week

Question 2

Onsite vs. offsite backups

Answer 2

• On site backups
  –No Internet link required
  –Data is immediately available
  –Generally less expensive than off site
• Off site backups
  –Transfer data over Internet or WAN link
  –Data is available after a disaster
  –Restoration can be performed from anywhere
• Organizations often use both
  –More copies of the data
  –More options when restoring

Question 3

Frequency

Answer 3

• How often to backup
  –Every week, day, hour?
• This may be different between systems
  –Some systems may not change much each day
• May have multiple backup sets
  –Daily, weekly, and monthly
• This requires significant planning
  –Multiple backup sets across different days
  –Lots of media to manage

Question 4

Encryption

Answer 4

• A history of data is on backup media
  –Some of this media may be offsite
• This makes it very easy for an attacker
  –All of the data is in one place
• Protect backup data using encryption
  –Everything on the backup media is unreadable
  –The recovery key is required to restore the data
• Especially useful for cloud backups and storage
  –Prevent anyone from eavesdropping

Question 5

Snapshots

Answer 5

• Became popular on virtual machines– Very useful in cloud environments
• Take a snapshot– An instant backup of an entire system– Save the current configuration and data
• Take another snapshot after 24 hours– Contains only the changes between snapshots
• Take a snapshot every day– Revert to any snapshot– Very fast recovery

Question 6

Recovery testing

Answer 6

• It’s not enough to perform the backup– You have to be able to restore
• Disaster recovery testing– Simulate a disaster situation– Restore from backup
• Confirm the restoration– Test the restored application and data
• Perform periodic audits– Always have a good backup– Weekly, monthly, quarterly checks

Question 7

Replication

Answer 7

• An ongoing, almost real-time backup– Keep data synchronized in multiple locations
• Data is available– There’s always a copy somewhere
• Data can be stored locally to all users– Replicate data to all remote sites
• Data is recoverable– Disasters can happen at any time

Question 8

Journaling

Answer 8

• Power goes out while writing data to storage– The stored data is probably corrupted
• Recovery could be complicated– Remove corrupted files, restore from backup
• Before writing to storage, make a journal entry– After the journal is written, write the data to storage
• After the data is written to storage, update the journal– Clear the entry and get ready for the next