16. Replication Resiliency
• Resiliency from Failures
• Retry and resume semantics
• Resynchronization
• Seamless handling of VM Mobility
• No admin intervention required
• Live Migration, Storage Migration and Quick Migration
• Within cluster and across cluster
17. VM Mobility
Site Site
A B
• Pre-requisites:
• Primary migration: All primary servers must be
authorized
• Replica migration: Requires Hyper-V Replica Broker
19. Planned Failover
• Testing DR or site maintenance or impending disaster
• Zero data loss but some downtime
• Efficient reverse replication
1. Shutdown primary VM
Site A Site B 2. Send last log
3. Failover Replica VM
4. Reverse replicate
20. Network Configuration on Replica
VM Connectivity on Replica Primary Replica
Vswitch creation and assignment 10.22.100.XX 15.25.10.XX
VLAN tagging
VM identity in a different subnet
Inject static IP address
Auto assignment via DHCP
Preserve IP address via Network Virtualization
Client
VM Name Resolution Server IP Address
Update DNS records to reflect new IP address Name
SQLVM 15.25.10.XX
10.22.100.X
X
26. Network Capacity
Capacity planning is critical
Estimate rate of data change
Estimate for peak usage and effective network bandwidth
15
Avg. Replication
Latency (mins)
10
5
0
0.5 GB 1 GB 3 GB 5 GB 7 GB 8 GB 10 GB
Uncompressed data transferred in 24 hrs
27. Network Throttling
• Use Windows Server 2012 QoS to throttle replication
traffic
• Throttling based on the destination subnet
New-NetQosPolicy “Replication Traffic to 10.0.0.0/8” –DestinationAddress
10.0.0.0/8 –MinBandwidthWeightAction 40
• Throttling based on the destination port
New-NetQosPolicy “Replication Traffic to 8080” –DestinationPort 8080 –
ThrottleRateActionBytesPerSecond 100000
28. Network Utilization
• Replicating multiple VMs in parallel
• Higher concurrency leads to resource contention and latency
• Lower concurrency leads to underutilizing
• Manage initial replication through scheduling
• Manage delta replication
Network bandwidth Ideal number of parallel
transfers
1.5 Mbps, 100ms, 1% packet 3 (Default)
loss
300 Mbps, 10ms, 1% packet 10
loss
29. Backup Interoperability
• Backup copy to seed Initial Replication
• Back-up Primary VM
• Concurrent backup and replication are handled
seamlessly
• Restore of Primary VM requires resync
• Back-up Replica VM
• Replica VM turned off
• Backup is on hold when VHD is modified by replication
• Restore of replica VM requires resync
30. Server Impact
• Impact on primary server
• Storage space: Proportional to writes in the VM
• Storage IOPS on ~ 1.5 times write IOPS
• Impact on replica server
• Storage space: Proportional to the write-churn
• Each additional recovery point ~10% of the base
VHD size
• Storage IOPS:
•
• Memory ~50MB per replicating VHD
• CPU impact <3%
32. In Review: Session Objectives and
Takeaways
• Relevance of Hyper-V Replica and when to use it
• Complements high availability and migration
• Capabilities and Value Proposition
• Inbox solution
• Flexible deployment scenarios
• Comprehensive replication and failover capabilities
• Deployment Considerations
• Network
• System Impact
• Back-up Inter-op
