01 Business Continuity Intro

7/31/2019 01 Business Continuity Intro

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siness Continuity Overview













































A “good” copy is one that is:

Consistent – captures all relevant data as a coordinated “snapshot”

Restorable – either at the volume level or file level

DurableNon-intrusive – does not interrupt current operations when

captured

Near Current




The Disaster Recovery timeline is defined around two key objectives:

Recovery Point Objective

How much data loss can you tolerate?

30 minutes

60 minutes24 hours

1 week

Zero is a valid answer!

Recovery Time Objective

How long can you tolerate being off-line?

Time is defined as not just the time to recover the data, butthe time to bring business operations back online




Procedures should be written so that secondary personnel are able to follow them

In a disaster situation, primary personnel may not be able to reach the recoverysite

For example, persons other than the primary email administrator should be ableto recover the email servers and confirm operation

Business leaders and IT personnel must agree on Recovery Time Objectives andRecovery Point Objectives. RPO and RTO are essentially service level agreementsdisaster recovery

Frequent review and updates to the plan are necessary to accommodate

Changes to server or application software

Additions to the IT environment, such as a new database or application server

Deployment of new IT tools, such as Dell EqualLogic Auto-Snapshot Manager

Periodic testing of the plan is necessary to ensure: that:

The plan covers all necessary IT Infrastructure

Personnel are capable of carrying out recovery tasks

DR infrastructure fully supports all operations

Servers

Storage

Applications

Data

Network







Each of the following plans are described in more detail later in this lesson.

Data Backup Plan

The plan that describes the detailed backup strategy for each

recoverable IT element (server, database, etc.)

Recovery plans provide detailed steps for recovering each element from

those backups

Server Recover Plan

Application Recovery Plan

Database Recovery Plan

Data Network Recovery Plan

Voice Network Recovery Plan

The Test Plan specifies frequency of testing, personnel assignments,pass/fail criteria, etc.

The Plan Maintenance specifies the update schedule for all the DR plans;it also specifies events that would trigger an out-of-schedule update,

such as deployment of a new application

1siness Continuity Overview









1. On the Backup Server, the backup process starts, which can be initiatedmanually or through a schedule:

The Backup Server notifies VSS on the target server that the data shouldbe backed up.

VSS notifies NTFS to prepare for the backup (for example, quiesce andflush the buffer cache).

VSS notifies the PS Series group to create a snapshot.

PS Series group creates the snapshot.

VSS notifies NTFS to resume operation.

2. The Backup Server backs up the data to backup media using the snapshot:

VSS notifies the Backup Server to import (mount) the snapshot, and thenthe Backup Server copies the data from the snapshot to backup

media, either disk or tape (such as a PS Series volume located in the

SAN or a tape device that is separate from the SAN).The Backup Server notifies VSS that the backup is complete.

3. VSS notifies the PS Series group to delete the snapshot.




The server recover plan specifies how to return the processinginfrastructure to service following either a physical disaster or data disaster

May also include application recovery (recover both servers andapplications in a single step)

Email storesDatabases

Specifies processes for recovery at both the local site (for example,after a hardware failure or software failure) and the remote site (fire,flood, etc.)

Specifies return to normal operation at either the original site, or at a newsite if original site is permanently lost

Dell EqualLogic Enhances the Plan by:Enabling frequent snapshots/replications of the system volume(Boot from SAN)

Local recovery, remote recovery, fast-failback to primary site,multiple recovery points




The database recovery plan specifies restoration processes to recover

specific databases that are critical to business operations.

Recovery processes for the both local site and the remote (DR) site

are defined

In-place recovery/rollback

Restore database at remote site on new server

How Dell EqualLogic enhances the plan: With HIT 3.0, application-

consistent snapshots and replications for Microsoft SQL Server 2005 can

be fully automated.

All volumes that contain database elements are identified and

backed up automatically per a user-defined schedule










Cold

Systems are idled and are not available for use during backupoperation

Application recovery is the same as normal system startup

“Good old backup”

Crash Consistent

A copy of all relevant data is captured at a single point in time

Application recovery is as if power was lost

Application Consistent

Application supports the ability to create a coordinated snapshot ofits data set.

Application supports recovery from the coordinated snapshot

Inconsistent

Data are not coordinated; usefulness is limited (but may be betterthan nothing)




Different types of backup offer varying degrees of:

Impact to the server being backed up

Heavy burden on the server is undesirable, because it

necessitates doing backups during a specified maintenance

window

At worst case, access to the server is completely restricted

during the backup operation (“Cold” backup)

Impact to users who are using the server

Will the users see poor performance when backup is

running?

Ease of recovery

The manner in which the backup is captured will impact both

Recovery Time and Recovery Point objectivesApplication Consistent copies offer the easiest and

fastest recovery

Crash Consistent copies are easy create, but recovery

may be more time-consuming and laborious.




“Cold” backups are what most people think of when they think of backup

Is often the cheapest and easiest to implement

May be as simple as using command line copy commands

Requires complete stoppage of application

Requires time to complete backup operation

Backed-up data is not immediately accessible. The data will be in a formatdefined by the backup application, and must be restored using the samesoftware used to perform the backup




Backup window is scheduled during off-hours

Users are notified in advance of service outage

EmailDatabase

Phone/Internet access

When window begins, applications are halted

Backup application runs and copies all relevant data to tape or disk

Applications are re-started and users are notified




Crash consistent copies are point-in-time copies of a volume or a set of

related volumes

May be stored locally (snapshot) or remotely (replica)

Crash-consistent copies are a very common form of data protection

Application data is in the same state as if a power failure occurred

Application must run recovery procedures to make the data usable

Procedures are typically run automatically when a server reboots




Current technology enables the creation of application consistent data

copies

Point-in-time snapshot capture is coordinated with the application

Application is momentarily paused (quiesced) just prior to thesnapshot being taken

All buffers and cache are flushed, so no data remains unwritten to

disk

Snapshot is captured of volume or volume set associated with the

application

Application is un-paused




Inconsistent snapshots are snapshots that span multiple volumes, but

which are not captured in a coordinated manner

For example, a database resides on 3 separate volumes, but the

volumes are backed up individually at different points in time

Applications cannot recover from inconsistent snapshots

It may be possible to manually recover pieces of data

For example, recovery of an accidentally deleted file

Inconsistent snapshots should be avoided (but they may be better than

nothing)










Snapshots may be crash-consistent or application-consistent depending

on implementation

Crash-consistent snapshots are easier to implement, but require

more effort during a recovery

Application-consistent snapshots involve more planning and setup,but offer faster recovery

Locally stored snapshots support favorable RTO and RPO times, but they

do NOT protect against a site outage

Snapshot Techniques

Copy-on-write

Allocate-on write

Snapshot considerations include

The time that it takes to perform the snapshot

The amount of storage space used by the snapshot

The burden placed on the application server by the snapshot

operation




Typical replication solutions are often time-consuming and require you to backup data and manually transport the backups to a different location.

Through Dell EqualLogic’s Snapshots and Auto-Replication capability, end-to-

end data protection capability is now possible for customers.At the primary site, snapshots are use to provide quick recovery, based on

Volume changes

Snapshot schedule

Risk

Need to recover

At the Remote site

Critical volumes or possibly all volumes are replicated

Backup to tape occurs at the replication secondary site, allowingfor all backups to happen at a central site

Secondary site is available for operation if the primary sites should

fail

Replication with Dell EqualLogic PS Series Storage arrays is performed betweengroups

Primary site is one group

Secondary site is a second group













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01 Business Continuity Intro