Chapter 12

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Backup and RecoveryBackup and Recovery

Chapter 12

Section 3 : Business Continuity


Chapter Objective

Upon completion of this chapter, you will be able to:

o Describe Backup/Recovery considerations

o Describe Backup/Recovery operations

o Describe Backup topologies

o Describe backup technologies


Lesson: Backup/Recovery Overview

Upon completion of this lesson, you be able to:

o Define Backup and backup consideration

o Describe purposes of backup

o Explain backup granularity and restore

o List backup methods

o Describe backup/recovery process and operation


What is a Backup?

o Backup is an additional copy of data that can be used for restore and recovery purposes

o The Backup copy is used when the primary copy is lost or corrupted

o This Backup copy can be created by:o Simply copying data (there can be one or more copies)o Mirroring data (the copy is always updated with whatever is written to the

primary copy)


It’s All About Recovery

o Businesses back up their data to enable its recovery in case of potential loss

o Businesses also back up their data to comply with regulatory requirements

o Backup purposes:o Disaster Recovery

o Restores production data to an operational state after disastero Operational

o Restore data in the event of data loss or logical corruptions that may occur during routine processing

o Archivalo Preserve transaction records, email, and other business work products for

regulatory compliance


Backup/Recovery Considerations

o What are the restore requirements – RPO & RTO?o If RPO is one day, data needs to be backed up at least once every day

o Where and when will the restores occur?

o What are the most frequent restore requests?

o Which data needs to be backed up?

o How frequently should data be backed up?o hourly, daily, weekly, monthly

o How long will it take to backup?

o How many copies to create?

o How long to retain backup copies?


Other Considerations: Data

o Locationo Heterogeneous platformo Local and remote

o Number and size of fileso Large files are faster to backup compared to multiple smaller files of the

same sizeo 10 files of 1MB size vs. 10000 files of 1KB size

o The use of data compression can save spaceo Text files compresses really wello Binary files cannot compress very wello Files such as JPEG and ZIP are already compressed and therefore is unlikely to

be compressed further


Backup Granularity

o Full backupo Backup of the complete data at a certain point in time

o Incremental backupo Copies data that has changed since the last full or incremental backupo Much faster, but takes longer to restore

o Cumulative (differential) backupo Copies data that has changed since the last full backupo Slower than incremental backup, but faster to restore

o Synthetic (constructed) full backupo A full backup generated from the latest full backup and all the incremental

backups performed after that full backupo Enables full backup copy to be done offline


Backup GranularityFull Backup

Su Su Su Su Su

Incremental Backup

Su Su Su Su SuM T TW F S M T TW F S M T TW F S M T TW F S

Cumulative (Differential) Backup

Su Su Su Su SuM T TW F S M T TW F S M T TW F S M T TW F S

Amount of data backup


Restoring from Incremental Backup

o Key Featureso Files that have changed since the last backup are backed upo Fewest amount of files to be backed up, therefore faster backup and less

storage spaceo Longer restore because last full and all subsequent incremental backups must

be applied

IncrementalIncremental

Tuesday

File 4


Wednesday

Updated File 3


Thursday

File 5 Files 1, 2, 3, 4, 5

ProductionProduction

Friday

Files 1, 2, 3

Monday

Full Backup


Restoring from Cumulative Backup

o Key Featureso More files to be backed up, therefore it takes more time to backup

and uses more storage spaceo Much faster restore because only the last full and the last cumulative

backup must be applied

CumulativeCumulative

Tuesday

File 4Files 1, 2, 3

Monday

Full BackupFull Backup CumulativeCumulative

Wednesday

Files 4, 5

CumulativeCumulative

Thursday

Files 4, 5, 6 Files 1, 2, 3, 4, 5, 6

ProductionProduction

Friday


Backup Methods

o Cold or offline

o Hot or online

o Backing up online production data is challenging because a file may be locked by the OS and cannot be copied until it is closed. There are two ways to handle thiso Retry until file is closed and can be accessedo Use Open File Agents

o Point in Time (PIT) replicao Copies snapshots of changed datao Consumes small space and can be created very quickly


Backup Methods

o Backup file metadata for consistency

o Boot sector and partition layout are critical for successful recovery

o Bare metal recovery (BMR)o All metadata, system information and applications configurations are

backed upo Builds the base system: partitioning, file system layout, operating system,

applications and all related configurations


Backup Architecture and Process o Backup client

o Sends backup data to backup server or storage node

o Backup servero Manages backup operations

and maintains backup catalog

o Storage nodeo Responsible for writing data to

backup device Backup Server/

Storage Node

Tape Library

Storage Array

Application Server/

Backup Client

Backup Data

Metadata Catalog

Backup Data


Backup Operation

1

Application Server and Backup Clients

Backup Server Storage Node Backup Device

2

7

3b 4

53a

6

3a Backup server instructs storage node to load backup media in backup device

Start of scheduled backup process1

Backup server retrieves backup related information from backup catalog

2

Backup server instructs backup clients to send its metadata to the backup server and data to be backed up to storage node

3b

Backup clients send data to storage node4

Storage node sends data to backup device5

Storage node sends media information to backup server

6

Backup server update catalog and records the status

7


Restore Operation

Application Server and Backup Clients

1

5

2

4

3

3

Backup Server Storage Node Backup Device

1 Backup server scans backup catalog to identify data to be restore and the client that will receive data

2 Backup server instructs storage node to load backup media in backup device

3 Data is then read and send to backup client

4 Storage node sends restore metadata to backup server

5 Backup server updates catalog


Lesson Summary

Key points covered in this lesson:

o Purposes for Backup

o Considerations for backup and recovery

o Backup granularityo Full, Cumulative, Incremental

o Backup methods

o Backup/recovery process and operation


Lesson: Backup/Recovery Topologies & Technologies

Upon completion of this lesson, you be able to:

o Describe backup topologieso Direct backupo LAN and LAN free backupo Mixed backup

o Detail backup in NAS environment

o Describe backup technologieso Backup to tapeo Backup to disko Backup to virtual tape


Backup Topologies

o There are 3 basic backup topologies:o Direct Attached Based Backupo LAN Based Backupo SAN Based Backupo Mixed backup


Direct Attached Backups

Backup DeviceApplication Server

and Backup Client

and Storage Node

Backup Server

LAN

Metadata Data


LAN Based Backups

LAN

Storage Node Backup Device

Data

Application Server

and Backup Client Backup Server

Metadata


SAN Based Backups (LAN Free)

DataMetadata

Backup DeviceBackup Server Application Server

and Backup Client

Storage Node

LAN FC SAN


Mixed Backup

Data

Metadata

Backup DeviceBackup Server Application Server

and Backup Client

Storage Node

LAN FC SAN

Application Server

and Backup Client

Metadata


Backup in NAS Environment – Server Based

NAS Head

Application Server

(Backup Client)

Backup Server/ Storage Node

Storage

Backup Device

Backup Request

Data

Metadata

LAN FC SAN


Backup in NAS Environment – Serverless

NAS Head

Application Server

(Backup Client)

Backup Server /

Storage Node

Storage

Backup Device

Backup Request

Data

Metadata

LAN FC SAN


Backup in NAS Environment – NDMP 2-way

NAS HeadApplication Server

(Backup Client)

Backup Server

Storage

Backup Device

Backup Request

Data

Metadata

LAN FC SAN


Backing up a NAS Device – NDMP 3-way

NAS Head

Application Server

(Backup Client)

Backup Server

Backup Request

Data

Metadata

NAS Head

StorageLAN

FC SAN

FC SAN

LAN

Backup Device


Backup Technology options

o Backup to Tapeo Physical tape library

o Backup to Disk

o Backup to virtual tapeo Virtual tape library


Backup to Tape

o Traditional destination for backup

o Low cost option

o Sequential / Linear Access

o Multiple streamingo Backup streams from multiple clients to a single backup device

TapeTape

Data fromStream 1 Data from

Stream 2 Data fromStream 3


Physical Tape Library

Drives

Cartridges

Import/

Export

Mailbox

Linear

Robotics

System

Front View Back View

I/O Management Unit

Server Class Main Controller

Power Systems

Drives


Tape Limitations

o Reliabilityo Restore performance

o Mount, load to ready, rewind, dismount times

o Sequential Access

o Cannot be accessed by multiple hosts simultaneously

o Controlled environment for tape storage

o Wear and tear of tape

o Shipping/handling challenges

o Tape management challenges


Backup to Disk

o Ease of implementation

o Fast access

o More Reliable

o Random Access

o Multiple hosts access

o Enhanced overall backup and recovery performance


Tape versus Disk – Restore Comparison

Typical Scenario: 800 users, 75 MB mailbox 60 GB database

Source: EMC Engineering and EMC IT

*Total time from point of failure to return of service to e-mail users

0 10 20 30 40 50 60 70 80 90 100 120110

Recovery Time in Minutes*

TapeBackup / Restore

DiskBackup / Restore

108Minutes

108Minutes

24Minutes

24Minutes


Virtual Tape LibraryBackup Server/

Storage Node

Backup Clients

Emulation EngineV

irtu

al T

ap

e L

ibra

ry A

pp

lian

ceStorage (LUNs)

LAN

FC SAN


Tape Versus Disk Versus Virtual Tape

Tape Disk-AwareBackup-to-Disk Virtual Tape

Offsite Capabilities Yes No Yes

Reliability No inherent protection methods RAID, spare RAID, spare

Performance Subject to mechanical operations, load times Faster single stream Faster single stream

Use Backup only Multiple (backup/production) Backup only


Data De-duplicationo Data de-duplication refers to removal of redundant data. In the de-duplication

process, a single copy of data is maintained along with the index of the original data, so that data can be easily retrieved when required. Other than saving disk storage space and reduction in hardware costs, (storage hardware, cooling, backup media, etc), another major benefit of data de-duplication is bandwidth optimization.


Lesson Summary

Key points covered in this lesson:

o Backup topologieso Direct attached, LAN and SAN based backupo Backup in NAS environment

o Backup to Tape

o Backup to Disk

o Backup to virtual tape

o Comparison among tape, disk and virtual tape backup


Chapter Summary

Key points covered in this chapter:

o Backup and Recovery considerations and process

o Backup and Recovery operations

o Common Backup and Recovery topologies

o Backup technologieso Tape, disk, and virtual tape


Check Your Knowledge

o What are three primary purposes for backup?

o What are the three topologies that support backup operation?

o Describe three major considerations of backup/recovery.

o What are the advantages and disadvantages in tape and virtual tape backups?

o What are the three levels of granularity found in Backups?

o How backup is performed using virtual tape library?


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Chapter 12

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