Mark Broadbent gave a presentation on achieving high availability for SQL Server in Windows 2016. He discussed several options including SQL Server failover clustering, availability groups, cluster shared volumes, SMB 3.0 file shares, and Storage Spaces Direct. He also demonstrated new features in Windows 2016 like stretch database, SQL on Azure infrastructure, domain-independent availability groups, and distributed availability groups. The presentation provided an overview of high availability strategies and new capabilities in the latest versions of SQL Server and Windows.

1. Mark Broadbent
Principal Consultant
SQLCloud
SQLCLOUD.CO.UK
Schizophrenic High Availability
with SQL
and
Windows
2016

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About
Mark Broadbent.
“30 billion times more intelligent than a live mattress”
Microsoft Certified Master/ Certified Solutions Master: SQL Server
Microsoft Data Platform MVP
Principal at SQLCloud
Email: mark.broadbent@sqlcambs.org.uk
Twitter: retracement
Blog: http://tenbulls.co.uk
Event Lead to the UK’s first ever SQLSaturday (Cambridge)
– now also SharePoint Saturday
Event #4 on 8/ 9/ 10th Sept 2016 (pre-cons & Community day)
http://sqlcambs.org.uk

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Agenda
Virtualization
3
Cluster
Storage
2
Import generic
Import generic
Import generic
The Road to
Schizophrenic HA
1
The best part of the presentation…
Gin-O-Clock
5
New and Cool HA
features
4

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In the beginning…

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Schizophrenic HADR
Serial Attached SCSIFibre Channel iSCSI
Import generic
Import generic
Import generic
SMB 3.0 Fileshare
Serial ATA is not supported
for cluster shared storage
?
??
?
?
?

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SQL Failover Clustering
• Clustered Application/ resource, active on one node at a time
• Requires Windows Cluster and a Windows Cluster which requires single Windows Domain
• Storage visibility
• Support multi-site/subnets but with considerations
• Quorum
• Storage replication
• Subnet IP or dependency
• WAN reliability
Cluster Shared Storage
Subnet 1 Subnet 2

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Availability Groups
• SQL now standalone but still requires Windows Cluster (quorum and HA components)
-remember the single domain 
• Read-only routing of read-only queries directed only to first available replica
• Support multi-site/subnets but with considerations
• Quorum
• Storage replication
• Subnet IP or dependency
• WAN reliability, Latency (log stream inefficiency)
Primary Replica
Subnet 1 Subnet 2
Availability Group
Resource
Currently no MSDTC and
cross database transaction
support in AG …but….
Secondary
Replica
Replica
Databases
Listener
async
sync
Availability group secondaries
may be readable replicas

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Cluster Shared Volumes for SQL FCIs
• Supported by SQL Server 2014 on Windows 2012 R2 (introduced
in Windows 2012)
• Consolidation of multiple SQL instances
• Large FCI cluster deployments could run out of drive letters
• Consolidating multiple SQL instances on single LUN makes the
storage utilization more efficient
• Fast failover – no dismount and mount during failover!
• Easier to configure and more resilient
• Zero downtime chkdsk
• Resilience from network failures (CSV can reroute traffic over the network
using SMB 3.0 allowing the SQL instance to remain operational
• Good for Hyper-V Cluster Storage but consider performance hit
from redirected IO

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SMB 3.0 File Shares
• SMB 3.0 supported by Hyper-V Windows 2012/R2 & SQL
2012/2014
• Not assigned to the Cluster
• Cannot be added to Cluster Shared Volumes
• Very easy to configure and consume
• Low cost connectivity
• No Filestream support Failover Cluster
File Server

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Scale-Out File Server Cluster
Failover Cluster
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
SSD
600GB
HDD
3TB
HDD
3TB
HDD
3TB
RDMA Cards
HBA Storage Adapters
JBOD Array
SMB
Multichannel
SMB Direct
RDMA
Continuous
Availability
File Share
Cluster
Shared
Volumes
Multipath
IO
Storage
Spaces
Failover
Clustering
Scale-Out File
Server
Infiniband Switches

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Microsoft Storage Spaces Direct
• Utilize high speed NVMe local storage or SATA
• Eliminate need for shared SAS Fabric
• Perfect for Hyper-V
• Disaggregated deployment (needs SoFS) or Hyper-converged stack
• Create Storage tiers

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Hyper-V scalability limits
Guest
• 64 vCPUs
• 1 TB Memory
• 64 TB VHDX virtual disks
• 4 Virtual Fibre Channel Adapters
• 12 Virtual NICs
Host
• 320 Logical processors
• 1024 virtual machines per host
• 4 TB Memory

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Hyper-V Benefits
• Replication
• Exports
• Live Storage Migration
• Live Migration
• Quick Migration
• Checkpoints (snapshots)
• QoS on disks, Bandwidth, CPU etc
• Fast Boot
• Azure portability *1
*1 Generation 2 Machines not compatible (although ASR can support)

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PhysicalInfrastructureGuestCluster
Hypervisors
Guests
Hyper-V Cluster
SQL Server Cluster
Storage Fabric
Guest Clustering on a Hyper-V Cluster
• Clustered Virtual Machines on
Hyper-V cluster
• SQL Clustered Instance can
failover to each VM in the Guest
Cluster
• Guest VM benefits from
“Clustered Live Migration” in
Hyper-V
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
HDD
3TB
SSD
600GB
HDD
3TB
HDD
3TB
HDD
3TB

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Stretch Database
EXEC sp_configure 'remote data archive', 1;
GO
RECONFIGURE
Single trickle thread (for now)
Automatically move cold table data to azure (row predicate should be possible)
Transparently query across table & Azure
orders
id status
1 0
2 2
3 1
4 0
Trickle thread

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SQL XI
• Data/ log files in Azure
• Bypass Azure limit of 16 VM disks
• Performance benefits to Virtual disks
• Bypasses Virtual Disk driver and passes through virtual network driver
• Cloud Portability

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DEMO
Hyper-V Live Migration, Stretch DB and SQLXI

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Azure Cloud Witness
• Windows 2016 Quorum Configuration
• Use Storage account name
• Primary or secondary key
• (optional) specify service endpoint
• Azure Witness uses HTTPS REST so https
port must be open on all cluster nodes
• If regenerating access key, first rotate to
secondary/ primary
• Set storage account to “Locally
Redundant” for Replication Type
Azure blob storage
Azure blob storage
msft-cloud-witness

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Direct Seeding
• Based on Azure Database seeding
• Group seeding per replica (manual seeding possible)
server1
server2
server3
File Server
TCP 5022 TCP 5022
Replica backup stream
Backup stream
Restore stream
Availability Group

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Read only routing - load balancing
• Read only routing list configured on primary role
• Applications must
• Connect through Listener
• Connection string must specify Application Intent=ReadOnly
• Parentheses identifies load balanced set
READ_ONLY_ROUTING_LIST=((‘server2’,‘server3’,‘server4’),‘server5’,‘server6’)
server1 server2 server3 server4 server5 server6

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Basic Availability Groups
• Standard Edition (or Enterprise)
• 2 replicas (configured on setup)
• No upgrade to advanced AG
• Cannot add or remove replicas
• No support for replicas prior to 2016
• Sync or Asyc
• No offloaded backups and no readable replica (snapshot possible)
• 1 Availability Group with 1 Database replica

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Domain-Independent Availability Groups
• Nodes must run Windows 2016
• Needs Failover Clustering Feature and DNS
• Intra-cluster communication via certificates
• Failover Cluster Manager GUI unsupported
• No Active Directory
New-Cluster -Name cluster3 -
Node server11,server12,server13
-AdministrativeAccessPoint DNS
server11 server12 server13
Workgroup1 Workgroup1
Cluster 3

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Distributed Availability Groups
• Cross cluster Availability Groups
• Addresses Site-to-site latency, disconnected remote site and
quorum considerations
• Forwarding Secondary synchronises with forwarded secondaries.
server1
Cluster 1, Availability Group X
server2 server3
server4
Server5
Cluster 2, Availability Group Y
Async replication stream
FP
S S S
53m

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Other new features
• MSDTC Support in Availability Groups
• Database level failover
• (but see https://connect.microsoft.com/SQLServer/feedback/details/2051070)
• Log shipping transport improvements
• Azure Replica Wizard
• Group Managed Service Accounts (gMSA)
• 3 synchronous replicas (3 auto failover targets)
• Cluster Operating System Rolling Upgrade
• Storage Replica
• File Snapshot Backup

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Thank you for listening!
Email: mark.broadbent@sqlcambs.org.uk
Twitter: retracement
Blog: http://tenbulls.co.uk