advanced site recovery -- technical briefing

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TopicsTopics

Why prepare for Site Recovery?

Traditional approaches

Motivation for splitting Disaster Recovery sites

ASR unique attributes

How it works

Scenarios

Combining HA with DR

ASR Look & Feel

Cut over procedure

Central site restoration


Why Prepare for Site Recovery?Why Prepare for Site Recovery?

Infrastructure failures Power, air conditioning, external network, etc.

Equipment maintenance HW/SW upgrade, repairs, reconfiguration

Facility closuresWater leaks, fire, building construction/move, security lockdown

Natural disastersFloods, earthquakes, storms, etc.


Regionally Distributed LocationsRegionally Distributed Locations

VM

Branch x

Internet

Central IT site


But, Single Disaster Recovery Site?But, Single Disaster Recovery Site?

DR Site

RemoteReplication

Central IT site

• Fat pipe

• Larger real-estate• More machines• Wasted resources

• High-end Storage• Identical systems


Low Cost Alternative: 1-to-Many DRLow Cost Alternative: 1-to-Many DR

VMVM

VMVM

Central IT site

HA

VM

VM

DR Site x

RemoteReplication

StorageVirtualization

• Thin pipes

StorageVirtualization


ASR Unique AttributesASR Unique Attributes

Take advantage of branch office locations

Distribute DR responsibilities• One central site protected by 2 or more smaller locations• Viable with lower speed WAN circuits• Standard Windows Servers virtualize storage using

Bi-directional replication

No application dependencies

No virtual machine dependencies

No host agents


Combining HA with DRCombining HA with DR

VMVM

VMVM

Central IT site

HARemote

Replication


ASR – How it WorksASR – How it Works

LUN LUN

look-alike replicas

ASR creates look-alike LUN replicas

LUN replicas are completely identical

Apps / VSEs / VMs don't encounter any differences

Apps / VMs can be started in any location without modification

Central IT Site DR Site

Remote Replication


ASR Data FlowASR Data Flow

Central IT siteCentral IT site

PP SS

SSDRDR

L1L1

HA Optional

DS1

DS1-DR

HourlySnapshots

TransmiTransmit Queuet QueueTransmiTransmit Queuet QueueSync

Mirror

SyncMirror

Mapped(online)

Mapped(offline)

12

L2L2

Only torestore

TransmitQueue

Kept currentwith DR site

3DR Site xDR Site x

Internet

WAN

PPDRDR


Failover: Two ScenariosFailover: Two Scenarios

Controlled Scheduled cut over No data loss Minimally disruptive

When: Major site maintenance Danger anticipated

• Imminent ice storm• Hurricane• Flooding

Relocation / facility move

Uncontrolled No warning Some data loss

• Buffered changes & cachesnever transmitted

Crash-consistent system recovery


Cut Over ProcedureCut Over Procedure

Controlled Suspend I/Os Flush caches Flush source buffer Await synchronization Restart on remote end

Uncontrolled Restart on remote end


PP SS

Central Site RestorationCentral Site Restoration

Internet

WAN

Central IT siteCentral IT site

PP SS

L2L2

PPDRDR

DS1

DS1-DR

Restore

TransmitQueue

Updated fromDR site

SyncMirror

Mapped(offline)

Mapped(online)

12

DR Site xDR Site x


Restoring Central SiteRestoring Central Site

Controlled Suspend I/Os on remote DR

site Flush caches Flush source buffer Await synchronization of all

dependent volumes Apply changes to original

virtual disks

Uncontrolled Re-initialize

Repeat for each DR site


Handling Link OutagesHandling Link Outages

Elastic source buffer sized to accommodate2 to 3 day WAN disruption

Switches automatically to log mode when space is exhausted

• Track blocks changed during outage• Transmit latest block contents when link is restored


Why Intermediate SnapshotsWhy Intermediate Snapshots

Ensure point-in-time consistency across groups of volumes

Separate from asynchronous updates that travel independently


Coordinating Dependent VolumesCoordinating Dependent Volumes

Group operations• Single request drives simultaneous action

across groups of virtual disks• In-band markers trigger remote snapshots

Simplifies distributed updates


How is ASR Delivered?How is ASR Delivered?

ASR Option - $2K per “region”

Multi-day Implementation service• Performed by an ASR-authorized and trained DataCore solution provider

Authorized partner requirements• DCIE (SANsymphony)• Attend ASR training (1 day)

Prerequisites• SANsymphony nodes at each end• Inter-site IP connections


Key Features of DataCore’sKey Features of DataCore’sAdvanced Site Recovery solutionAdvanced Site Recovery solution

Fast• Keeps DR site

up to date

Automated Eliminates error prone,

manual steps

Universal• Works equally well for

virtual & physical servers or different applications

Distributed • Accounts for multiple

sites / branch locations

Bi-directional• Resume operation at

original location

Verifiable• Easy to regularly

test / confirm recovery


Questions ?????

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