fault tolerance and disaster recovery. topics using antivirus software fault tolerance –power...
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Fault Tolerance and Disaster Recovery
Topics
• Using Antivirus software• Fault tolerance
– Power– Redundancy– Storage– Services
• Disaster Recovery– Backup/Restore– Offsite storage– Hot and Cold spares– Hot, warm, and cold sites
Assessing Fault Tolerance and Disaster Recovery Needs
• A proper disaster recovery plan encompasses planning and preparing for a network disaster, but also recovering from it.
• A disaster is anything that destroys data or attempts, either deliberately or accidentally, to impair network operation.
• Disaster recovery is often taken too lightly and many administrators come to regret it.
Prepared for Disaster
• Hot site• Warm site• Cold site
Hot Site
• In a hot site, every computer system and piece of information has a redundant copy.
• This level of fault tolerance is used when systems must be up 100 percent of the time.
• Hot sites are strictly fault-tolerant implementations, not disaster recovery.
Two Levels of Clustering
• Failover Clustering– Active and passive servers– Uses a heart beat to detect failure
• Advantages and Disadvantages
• True Clustering– Supports multiple devices– Provides load balancing
• Advantages and Disadvantages
Fault Tolerance
One system fails, one takes overOne system fails, one takes over
100% of clients100% of clients
Warm Site
• In a warm site, the network service and data are available most of the time.
• The data and services are less critical than those in a hot site.
• The most commonly used warm-site technology is a duplicate server.
• This is Disaster Recovery not fault-tolerance
Cold Site
• A cold site cannot guarantee server uptime.
• If a server fails, the IT personnel will do their best to recover and fix the problem
Power Management
• Surge Protectors• Battery Backup• Line Conditioners• Power management is for fault
tolerance
Surge Protectors
• Level of Protection– Only covers Over-voltage– Common Components
• Active Protection Light• Site Wiring Fault Light• Ground• IEEE 587 Category A (ANSI/IEEE
C62.41) Let-Through• UL Listing• Circuit Breaker• Additional Ports
Battery Backup
• Battery backup systems protect computer systems from power failures.– Under-Voltage
• Brown outs• Black outs
– Two Main Types of Battery Backup• Standby Power Supply• Uninterruptible Power Supply
Standby Power Supply
• Power is supplied from the AC unit• Battery is backup only• Uses a micro-switch to change power
sources in the event of a power failure– They may include:
• Surge protection• Multiple outlets• Line voltage indicator• Batter power indicator• System management port
Uninterruptible Power Supply
• Power is supplied through the battery• Batteries must be replaced regularly
– They may include:• Multiple outlets• Line voltage indicator• Batter power indicator• System management port
Line Conditioners
• Dirty power introduces noise in the system.
• This can cause many types of problems, including – random lockups, – random reboots, and – system crashes.
Disk System Fault Tolerance
• Mirroring• Duplexing• Data striping• Redundant Array of Independent (or
Inexpensive) Disks (RAID)
Partitions
Primary partitionsPrimary partitions
Extended partition with logical drives
Extended partition with logical drives
Physical diskPhysical disk CCCC
DDDD
E F GE F GE F GE F G
RAID
Data written to multiple disksData written to multiple disks
Data can be restored if one disk fails
Data can be restored if one disk fails
Striping (RAID 0)
Data
DDDD AAAA TTTT AAAA
Mirroring or Duplexing (RAID 1)
Disk controllersDisk controllers
Data
DATADATADATADATA DATADATADATADATA DATADATADATADATA DATADATADATADATA
Data
Drive 0 Drive 1 Drive 0 Drive 1
MirroringMirroring DuplexingDuplexing
Striping with Parity (RAID 5)
Data
DDDD
DDDD
DDDD
DDDD
ParityParityParityParity
ParityParityParityParity
AAAA
DDDD
AAAA
AAAA
ParityParityParityParity
TTTT
AAAA
AAAA
TTTT ParityParityParityParity
AAAA
TTTT
TTTT
TTTT
ParityParityParityParity
AAAA
AAAA
AAAA
AAAA
Backup Considerations
• Backup Media Options• Small-Capacity Removable Disks• Large-Capacity Removable Disks• Removable Optical Disks• Magnetic Tape
Backup Policies
Backup policy
Testing
Hardware and media
Administration
Software
The Standard Procedure for Database Backup
Procedure for backing up a database:1. Take database offline2. Back up the database files3. Clear the circular logs4. Put the database back online
Standard Procedure for Database Restoration
Procedure for restoring a database:1. Take database offline2. Restore database from latest tape3. Put database back online and do not
allow clients to connect4. Play back the circular logs5. Allow users to connect
Data Backups
Your company’s last line of defenseConsiderations:
What value does the data have?How will the backup be stored?
TapeDiskCloud
What procedure will be used?
Backup Media Types
TapesTapes Hard disksHard disks CD- and DVD-ROMsCD- and DVD-ROMs Cloud servicesCloud services
Backup Types
FullFullDifferentialDifferential IncrementalIncremental
Full backupFull backup
Am
ou
nt
of
da
ta
Am
ou
nt
of
da
ta
100%
50%
Am
ou
nt
of
da
ta
1 2 3 4 5
1 2 3 4 5 1 2 3 4 5
100%
50%
100%
50%
FullFull
Backup Types
Type What is Backed up
Archive Bit Cleared?
Number of sets to restore
Full All Data Yes Full only
Differential Since Last Full Backup
No Full plus Last differential
Incremental Since Last Backup
Yes Full plus every daily incremental to the last Full backup
Monthly tapes: 12 plus 1 extra
Daily tapes: 4 for Mon – Thur, plus 1 extra Weekly tapes: 4 Fridays, plus 1 extra
The GFS Rotation Method
The Tower of Hanoi Rotation Method
Day
Me
dia
Se
t
Media Set
Used Every
A 2 days
B 4 days
C 8 days
D & E
16 days alternating between set D and E
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
A A A A A A A A
B B B B
C C
D
E
Maintaining a Data Backup System
Backup maintenanceMaintain the data integrity
Test your backups
Maintain your hardwareInspect tapesClean drives
Data Backup System Maintenance
• Verify backups• Test restoration• Review logs• Replace tapes on
schedule• Maintain tapes and tape
drives• Clean tape drives• Replace damaged tapes
Backing Up Remote Users and Workstations
1. Must be online and powered up2. Remote users may require a
method of backup that allows them to back up from the road
3. Consider Web-based backups
Specialized Data Backups
Enterprise backupsMobile usersPower userworkstations
Open files Database Email
Virus Protection
• Types of Viruses– File Viruses– Macro Viruses– Boot Sector Viruses– Hoax Virus
Updating Antivirus Components
• A typical antivirus program consists of two components:– The definition files– The engine
Scanning for Viruses
• Two types of antivirus scans:– On-demand– On-access
Software Revisions
Is It Necessary? Where to Get PatchesHow to Apply Patches
Summary
• Summary• Exam Essentials• Review Questions