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Disk Based Disaster Recovery & Data Replication Solutions. Gavin Cole Storage Consultant SEE. Agenda. Planning for a Disaster Using Local Copies for Protection Using Remote Mirroring for Protection Conclusion. Agenda. Planning for a Disaster Using Local Copies for Protection - PowerPoint PPT Presentation
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Disk Based Disaster Recovery & Data Replication SolutionsGavin ColeStorage Consultant SEE
Agenda Planning for a Disaster Using Local Copies for Protection Using Remote Mirroring for Protection Conclusion
Agenda Planning for a Disaster Using Local Copies for Protection Using Remote Mirroring for Protection Conclusion
Disaster
Jon William ToigoChairman, Data Management Institute2005
any interruption in the normal access to a valid set of data used by applications and end users to execute mission critical business processes for an unacceptable period of time.
Hardware 44%
Operator 32%
Software 14%
Virus 7%
Disaster 3%
Causes of Data Loss 2002
Source: Ontrack Data Report 2007
Hardware 59% Operator 26%
Software 9%
Virus 2%Disaster 2%other 2%
Causes of Data Loss 2006
Source: Ontrack Data Report 2007
The threat of data loss can’t be ignored
• Risks:> High cost of data loss and downtime> Insufficient data recovery plans and procedures > 70% of businesses fail after major data loss > Recovery overextends limited staffs and financial
resources
• Needs:> High availability and fast data recovery > Seamless integration with existing IT infrastructures > Interoperability with current and future storage and
computing systems
The Cost of Downtime• Forrester Consulting Interviewed 138 companies• Estimated cost of 1 hour downtime
> Less than $10,000 / hr – 25%> $10,000 to $100,000 / hr – 33%> $100,000 to $500,000 – 25%> $500,000 to $1 million – 13%> Greater than $1 million – 4%
• 67% - could not estimate the financial cost of downtime
Disaster
Key definitions
Last safeBackup
Resumptionof normalbusiness
Recovery Point Objective (RPO)
The time between the last safe backup and the point of
time of the disaster
Recovery Time Objective (RTO)
The time elapsed from when the disaster occurred to the
resumption of normal business activities
Business Continuity• Planning to never go down• Always have access to information• Needs more than a good data recovery strategy• A disaster can be something as simple as a deleted
file• Use disk duplication strategies
> Mirroring> Snapshot> Remote replication
SecondsMinutes
HoursDays
Regional Disaster
Local Disaster
Operator error
Hardware failure
Application
Department
Data Center
Enterprise
RiskDisruption
Scale
Complete data protection requires personalized and practical solutions
Business goalsThreatsBudget realitiesExisting assets
Seven Key Planning Steps1. Business impact assessment
How long can I live without data?2. Discovery
What data do I need first?3. Budget
What is my data worth?4. Role-based teams
Who are the key people?5. Data protection
How do I protect what I need?6. Logistics
What are the physical requirements?7. Testing
Will my plan work?
Agenda Planning for a Disaster Using Local Copies for Protection Using Remote Mirroring for Protection Conclusion
Volume Copy TermsComplete point in time replication of one Volume (source)
to another (target) within a Storage Subsystem
Source = Volume that accepts host I/O and stores application data
Target = Volume that maintains a copy of the data from the source
Target or Copy or Clone
Copy Pair
How Volume Copy Works
SnapshotSnapshot- a logical point-in-- a logical point-in-time image of time image of another volume. another volume. Logical equivalent of Logical equivalent of a complete physical a complete physical copycopy
Logical Disk Space
Snapshot Terms
Storage SystemStorage System
Base Base VolumeVolume- the volume from - the volume from which the which the Snapshot will be Snapshot will be createdcreated
Physical Disk Space
Repository Repository – stores original – stores original blocks from Base blocks from Base before they are before they are overwritten with overwritten with new datanew data
Physical Disk Space
• A point-in-time (PiT) image of a volume > Logical equivalent of a physical copy
Snapshot Flow Chart
Using Volume Copy and Snapshot togetherCopying the Snapshot creates a full PiT clone copy
while I/O continues to base volume (LUN)
Agenda Planning for a Disaster Using Local Copies for Protection Using Remote Mirroring for Protection Conclusion
Remote Volume Mirroring
• Ongoing, real-time replication of a volume from one storage system to another
Remote Volume Mirroring ComponentsPrimary volume: accepts read and write host I/OSecondary volume: accepts read host I/O. accepts remote writes of data from controller owner of Primary
volume.
Primary Secondary Secondary Primary
Remote Volume Mirroring ComponentsMirror Repository volume: Stores mirroring
data, such as info about remote writes that have not completed
Primary Secondary Secondary Primary
MirrorRepositories
MirrorRepositories
Mirror PairsV1 -> V1MV2 -> V2MV3 -> V3M
Synchronous Replication • The primary disk system acknowledges a host write when
the data has been successfully mirrored
• Primary benefit> Ensures remote data is an exact replicate of the local
data• Note: only effective for campus area replication
• Primary benefits> Reduces impact of latency when replicating over longer distances
> Provides performance improvement – compared to synchronous – for primary site I/O (disk system and application)
> Enables effective replication over longer distances (WAN)
• Allows the primary disk system to acknowledge a host write request before the data has been successfully mirrored
Asynchronous Write Mode
• Write operations to the secondary disk system matches I/O completion order on the local disk system > Also referred to as a consistency group
• Primary benefit> Maintains data integrity in multi-LUN applications (databases)
by eliminating out-of-order updates at the remote side that can cause logical corruption
Preserved Write Order
Remote Volume Mirroring Mirror Management• Role Reversal (from secondary to primary or vice
versa) is user-initiated> If primary is also base volume for snapshots, role
reversal will cause associated snapshots to fail> It is possible to force role change for the local volume
if communication to the remote volume is down> Used in disaster recovery scenarios
> Can prepare by mapping secondary volumes to hosts using Storage Partitions before they are promoted
DR / HA ArchitectureCluster 1
Cluster 2
Volume 3 replication
Volume 1 & 2 replication
Site A Site B
* M = mirror * M = mirror
Architecture Description Site A and Site B each contain a copy of critical data Critical data is copied in real time using the disk controllers
minimal impact on server processing power OS and key applications are clustered across both sites
If either site fails application transparently fails over to remote Customers notices minimal disruption
2 way Disaster Protection Cluster 1 uses volume V1 and V2 – primary business is at Site A,
Mirrored to Site B for protection Cluster 2 uses volume V3 - primary business is at Site B, Mirrored
to Site A for protection Sites are connected by Fibre Channel network for performance
Could be connected by long distance IP network – will be performance impact on replication.
Agenda Planning for a Disaster Using Local Copies for Protection Using Remote Mirroring for Protection Conclusion
Could you survive a disaster?
• 35% of companies have a plan• 60% of plans are never tested• Half the companies that suffer losses never
recover• $10 – $50 K per MB to re-create data
Seven Key Planning Steps1. Business impact assessment
How long can I live without data?2. Discovery
What data do I need first?3. Budget
What is my data worth?4. Role-based teams
Who are the key people?5. Data protection
How do I protect what I need?6. Logistics
What are the physical requirements?7. Testing
Will my plan work?
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Thank You
Gavin Cole
+33 6 70 72 99 53
Disaster Recovery Planning