1 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  Using Remote Mirroring for Protection  Conclusion

Disaster Jon William Toigo Chairman, Data Management Institute 2005 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.

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 safe Backup Resumption of normal business 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

Seconds Minutes Hours Days Regional Disaster Local Disaster Operator error Hardware failure Application Department Data Center Enterprise Risk Disruption Scale Complete data protection requires personalized and practical solutions Business goals Threats Budget realities Existing assets

Seven Key Planning Steps 1.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 Terms Complete 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

Snapshot - a logical point-in- time image of another volume. Logical equivalent of a complete physical copy Logical Disk Space Snapshot Terms Storage System Base Volume - the volume from which the Snapshot will be created Physical Disk Space Repository – stores original blocks from Base before they are overwritten with new 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 together Copying 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 Components Primary volume: accepts read and write host I/O Secondary volume: accepts read host I/O. accepts remote writes of data from controller owner of Primary volume. Primary Secondary Primary

Remote Volume Mirroring Components Mirror Repository volume: Stores mirroring data, such as info about remote writes that have not completed Primary Secondary Primary Mirror Repositories Mirror Repositories Mirror Pairs V1 -> V1M V2 -> V2M V3 -> 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 Architecture Cluster 1 Cluster 2 Volume 3 replication Volume 1 & 2 replication Site ASite B * 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 Steps 1.Business impact assessment HHow long can I live without data? 2.Discovery WWhat data do I need first? 3.Budget WWhat is my data worth? 4.Role-based teams WWho are the key people? 5.Data protection HHow do I protect what I need? 6.Logistics WWhat are the physical requirements? 7.Testing WWill my plan work?

32 Thank You Gavin Cole Disaster Recovery Planning