This document provides information on Pure Storage's ActiveCluster solution, which allows for synchronous replication between two Pure Storage arrays for high availability and disaster recovery. Key points include: - ActiveCluster provides synchronous replication between two arrays located in different sites, with zero RPO, RTO, and additional hardware costs. - It allows for read/write access to the same volumes from either array, with automatic non-disruptive failover and resynchronization. - An integrated Pure1 Cloud Mediator or on-premises mediator is used for transparent failover without needing a third site. - ActiveCluster supports various configurations depending on latency between sites, including uniform access across sites or non-uniform

2. © 2017 PURE STORAGE INC.2
ActiveCluster
CLOUD MEDIATOR
COMPUTE COMPUTE
Multi-Site Active / Active
Zero RPO, Zero RTO, Zero $€￥£, Zero Additional HW
ACTIVE ACTIVE

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SYMMETRIC ACTIVE/ACTIVE
Read and write to the same volumes at either side of the mirror.
TRANSPARENT FAILOVER
Automatic non-disruptive failover with automatic resynchronization.
ASYNC REPLICATION INTEGRATION
For baseline transfers, resynchronization, and 3rd site DR.
NO BOLT-ONS & NO LICENSES
Upgrade Purity and go active/active!
SIMPLE MANAGEMENT
Data management operations work from either side of the mirror.
PURE1 CLOUD MEDIATOR
Integrated cloud based transparent failover mediation, no need for a 3rd site.
ActiveCluster

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ActiveCluster
DATA CENTER
METRO GLOBAL
LIVE MIGRATION
RACK HA
ACTIVE CLUSTER
W/ TRANSPARENT FAILOVER
THREE DATACENTER
(ASYNC THIRD SITE)
1
2
3
4
RACK1 RACK2
UP TO 11ms RTT
ANYWHERE
CLOUD MEDIATOR
SITE A SITE B

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ActiveCluster

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ACTIVE/ACTIVE SIMPLIFIED
A single array exposes multiple
volume paths to a host
Add a 2nd array and connect them
Groups of volumes are stretched,
and the data is synchronized
Writes get synchronously mirrored
before being acknowledged
Expose the same volumes from
both arrays
Two volumes look like one volume,
the host simply sees more paths
CA
B
CA
B
CA
B
Hosts or Host Groups
VM
APP
VM
APP
VM
APP
Apps or VMs
CONFIDENTIAL DOCUMENT, DO NOT SHARE 2 OR DISTRIBUTE.

7. © 2017 PURE STORAGE INC.7
WHAT IS A POD?
pod1
pod2
pod4pod3
Stretched Pod
Stretched Pod
CA
B
CA
B
FD
E
CA
B
A pod is the unit of failover
for synchronous replication
A pod is…
…a namespace
…a consistency group
A pod can…
…contain protection groups
…replicate host information
…replicate metadata

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Datacenter/Campus HAUniform Storage Access Configuration
Active/Optimized
Uniform Configuration:
Optional configuration for
arrays deployed adjacent to
each other
Host are connected across
sites - hosts have access to all
arrays
Paths are presented to all
hosts as Active/Optimized
MPIO can use any path
Latency between arrays must
be minimal
Active/
Optimized
Active/
Optimized
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
Apps/VMs
Site 1 Site 2
Pod: Stretched Group of Volumes & pgroups
CA
B
CA
B
CA
B
CONFIDENTIAL DOCUMENT, DO NOT SHARE 2 OR DISTRIBUTE.
< 1ms RTT

9. © 2017 PURE STORAGE INC.9
Metro Area HAUniform Storage Access Configuration
Active/Non-optimized
Uniform Configuration:
Host are connected across
sites - hosts have access to all
arrays
Paths are presented to local
hosts as Active/Optimized
Paths are presented to remote
hosts as Active/Non-Optimized
ALUA MPIO keeps IO on
Optimized paths
Active/
Optimized
Active/
Optimized
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
Apps/VMs
Site 1 Site 2
Pod: Stretched Group of Volumes & pgroups
CA
B
CA
B
CA
B
CONFIDENTIAL DOCUMENT, DO NOT SHARE 2 OR DISTRIBUTE.
< 11ms
RTT

10. © 2017 PURE STORAGE INC.10
Metro Area HANon-Uniform Storage Access Configuration
Non-Uniform Configuration:
Host have connectivity to
storage only in the local site
All paths presented as ALUA
Active/Optimized paths
MPIO can use any local path
Active/
Optimized
Active/
Optimized
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
Apps/VMs
Site 1 Site 2
Pod: Stretched Group of Volumes & pgroups
CA
B
CA
B
CA
B
CONFIDENTIAL DOCUMENT, DO NOT SHARE 2 OR DISTRIBUTE.
< 11ms
RTT

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High Availability and Failover Mediation
Designed together for maximum availability and split brain protection
Integrated mediation for isolation awareness and HA
Arrays mediate between themselves and with a 3rd site mediator
Passive 3rd site mediator provides isolation awareness and allows arrays to determine
proper fault response, but is not required for continuous operation
An optional per pod setting can give failover preference to one array
Mediation configuration options
• Pure1 Cloud Mediator - mediator in the cloud, hosted by Pure Storage
• Mediator VM - hosted by Customer on a 3rd site, independent of both arrays

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Pure1 Cloud Mediator
Maintained by Pure Storage in the cloud
• Automatically discovered and configured by sync rep enabled arrays
• No need to deploy, maintain, upgrade and security patch another component
• Always-on mediation available from anywhere and by default at an external site
Passive mediator (vs active mediator)
• Passive mediator does not directly execute array failovers
• Passive mediator provides isolation awareness for arrays and stores pod state
Mediation is required when:
• A failure has already occurred, ex: link between arrays lost
• Forcing non-preferred side of pod online or cold boot without other array

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CA B

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HA Scenario: one array loses contact with mediator
Scenario: One array loses contact with mediator
Array1 loses mediator
(can still see other array)
Arrays remain in sync
Array1:
- Both arrays are still in sync,
so volumes remain online
- All paths remain online
Array2:
- Both arrays are still in sync,
so volumes remain online
- All paths remain online
CA
B
Stretched Group of Volumes & pgroups
CA
B
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
Pure1 Cloud Mediator
Array1 Array2
CA B

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HA Scenario: one array becomes isolated
Scenario: One array becomes isolated
Pods on Array1 become isolated
(cannot see other array or
mediator)
Arrays are out of sync
Array1:
- Volumes in sync-rep group go
offline on isolated array
- Paths to sync-rep volumes go
offline
Array2:
- Volumes remain online
- Local and remote paths
remain
*Non-sync rep enabled volumes
(ie local) on isolated array
remain online
Stretched Group of Volumes & pgroups
CA
B
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
Pure1 Cloud Mediator
Array1 Array2
*
CA B

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HA Scenario: mediator becomes temporarily unavailable
Scenario: Mediator becomes temporarily unavailable
Both arrays lose 3rd mediator
(can still mediate array-to-array)
Arrays remain in sync
Array1:
- Both arrays are still in sync,
so volumes remain online
- All paths remain online
Array2:
- Both arrays are still in sync,
so volumes remain online
- All paths remain online
Stretched Group of Volumes & pgroups
CA
B
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
Pure1 Cloud Mediator
Array1 Array2
CA
B
CA B

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AUTOMATIC RESYNC
CA
B
CA
B
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
RESYNCCA
B
Changes while out of sync are
tracked on the online side
When link is restored arrays
automatically resynchronize
using dedupe aware async
Access to volumes is
automatically restored when
resync is complete
CLOUD MEDIATOR

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CLOUD MEDIATOR
AUTOMATIC RESYNC
Changes while out of sync are
tracked on the online side
When link is restored arrays
automatically resynchronize
using dedupe aware async
Access to volumes is
automatically restored when
resync is complete
CA
B
CA
B
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
VM
APP
CA
B
CLOUD MEDIATOR

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High Level Requirementshttps://support.purestorage.com/FlashArray/PurityFA/Protect/Replication/ActiveCluster_Requirements_and_Best_Practices
• Two Pure Storage arrays, can be dissimilar
• Purity software update to 5.1.5 (for latest enhancements)
• Two additional management IP addresses
• IP based interconnect (10GbE in version 1), 8 connections & IPs (four per
controller)
• 11ms (was 5ms) maximum round trip latency between sites – and no more!
• Engineering have not tested beyond this latency
• Mediator - Pure1 Cloud Mediator or On Premises Mediator

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PERFORMANCE PLANNING GUIDANCE
ARRAY REQUIREMENTS
• Workload: One array in the cluster must support the entire workload at a minimum
(e.g. size for acceptable performance during a failover)
• Capacity: Each array needs space to hold a full copy of sync replicated data
HEAD ROOM
• Max 80% capacity in the arrays
• Use the sizer and pick configs less than 60% busy. Then use two of those because it's
active/active sync rep
PERFORMANCE GOALS FOR GA
• Write latency overhead: 0.3-0.5 ms sync rep processing overhead + 1 RTT
• Read latency overhead: Minimal; reads are handled locally

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ActiveCluster - Host OS Support
Always check
https://support.purestorage.com/FlashArray/Getting_Started/Compatibility_Matrix
Sample extract below ....