Lecture 15 : Backups

1
Lecture 15 Backups

• Reading - W2KER Ch. 5 (LAH Ch. 10 Storage
  Mountain)
• Introduction
• Backup types
• Software
• Users
• Machines
• Policies
• Finances

2
Introduction

• Dan Geer (a security consultant) has said
  something to the effect that Backups reliably
  violate security policies at a distance.
• Three Reasons for Restores
• Accidental file deletion
• Disk failure
• Archival
• As we discuss backups and restores, you should
  keep these three in mind.

3
Backup Types

• Full Backup
• Backs up all selected files
• Differential Backup
• Backs up all files that have been changed since
  the last full backup
• Incremental Backup
• Backs up all files that have been changed from
  the most recent backup (either a full or previous
  incremental)
• Delta Backup
• Similar to an incremental backup, but backs up
  only the actual data in the selected files that
  has changed, not the files themselves.
• Newer methods
• Real-time backup
• Others?

4
Software

• Files
• Open files
• Files with holes
• De-duplication
• Backup software
• Does it understand applications, or just files?
• How do restores work? (can users do their own or
  not)

5
Users

• Users
• Management (e.g., Disaster Recovery
  Implementation Plan/Business Continuity Plan)
• End-users (restores)
• Backup operators (manage the backups)
• Legislators (laws and policies)

6
Machines

• Machines
• Disks
• Tapes
• Tape drives
• Robots
• Newer forms of data handling
• Online backups
• Peer to peer
• Others?

7
Policies/Other Considerations

• How often do you do a full backup?
• What is your backup schedule?
• What is your backup window?
• How long do you need to retain data?
• How often can you recycle tapes (or disks)?
• What are your SLAs on restores? Are SLAs on
  restores of recent data higher than those on
  older data?
• Is your organization subject to any special
  legislation on data retention?
• How much data do you need to back up?
• What are your storage costs?

8
Backup Cost Exercise

• In-class SA finance questions, assuming you have
  the following tape drive
• Quantum SDLT 320
• Can back up 115G per hour
• Can store 320G on a single cartridge (compressed)
  
• List price roughly 3000

9
Backup Cost Exercise (cont.)

• Assume your environment is as follows
• 100 desktops, each with a 40G hard drive
• 2 file servers with 1T each
• 1 web server with 200G
• 1 database server with 200G
• Answer the following questions
• Assuming you back up everything, how long would
  it take to do a full backup?
• Assume the CEO comes to you and says that full
  backups must be taken every day. How would you go
  about providing him a cost of backup hardware
  (using the SDLT 320)?
• Assume that a restore takes 5 times as long as a
  backup. If the CEO asks you about using the
  backup tapes as a disaster recovery mechanism,
  how would you assemble a time-table of
  restoration?

10
Backup Cost Exercise (cont.)

• Develop a reasonable backup schedule, and explain
  why you think is it reasonable.
• Express your backup architecture as a ratio
  against the baseline IT budget for your company
  (assume 2 SAs _at_ 50K each, 1 operator _at_ 20K, and
  choose reasonable costs for the systems outlined
  above).
• Present an IT budget, complete with SUM pie
  chart. Include price information on Veritas
  NetBackup software in your budget.
• The final part of your budget should be a cost
  comparison of running a completely free software
  shop versus a commercial software office.

11
Up Next

• Final
• Before next class
• Homeworks
• HW8 - due
• HW9 - due
• Next class
• Final Quiz