SQL Server Failover Clustering has traditionally been deployed on physical architecture for a very long time, and is considered by many to be the optimal architectural deployment even today. Experienced High Availability implementors and pioneers will remember the Microsoft Cluster Hardware Compatibility List with terror and early Virtualization adopters will recoil in disgust at their memories of poorly performing SQL Server VM deployments and will never want to go back there again. Times are changing and with the introduction of Microsoft's Scalable Shared File Server and improvements to Hyper-V Clustering, High Availability will never be the same again. In this session we will investigate whether times have really changed for the better and discuss how to implement, administrate and benefits of running a Cluster on a Cluster from a Cluster!

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Mark Broadbent
Principal
SQL Consultant
SQLCloud
SQLCLOUD.CO.UK
Tri le Troublep

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About
Mark Broadbent.
“30 billion times more intelligent than a live mattress”
Microsoft Certified Master/ Certified Solutions Master: SQL Server
Owner/ Principal at SQLCloud
Useless fact: I’m a Chelsea supporter and I firmly believe that Porto got
LUCKY in the Champions League!!!
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
http://sqlcambs.org.uk

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Agenda
Overview from 50,000
feet
1
Hyper-V and Hyper-V
Clustering
3
Cluster
Storage
2
Import generic
Import generic
Import generic
Guest
Clustering
4
The best part of the presentation…
Super Bock O‘Clock
5

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So what exactly is a Cluster?
• Shared Everything vs Shared Nothing
• A compromise between scalability and flexibility
• Or simplicity over complexity
Cluster App A Cluster App A
Cluster App A Cluster App A
Shared Everything
Cluster App A
Shared Nothing
*1
*1 The term Shared Nothing in this scenario is a little misleading

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So what exactly is a Cluster?
• Shared Everything vs Shared Nothing
• A compromise between scalability and flexibility
• Or simplicity over complexity
Cluster App A Cluster App A
Cluster App A Cluster App A
Shared Everything
Cluster App A
Shared Nothing
*1
But the lines are getting blurred!
CA File Share CA File Share
CA File Share CA File Share
Shared Everything!

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SQL Server at 50,000 feet
• Traditional SQL Deployments on physical hardware are fairly
straight foreword
SQL Instance
WindowsOS
Storage
SQL installation requires Operating System (yeah Duh!)
And Operating System requires “locally attached”
storage to the physical server
Important to see distinction between physically attached local storage,
and remote, the latter potentially coming from lots of different places and
used by many different Services or Platforms
Storage

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Hyper-V Clustering
SQL Server “Triple Trouble” at 50,000 feet
Windows Clustering
SQL Failover Clustered
Instance
Windows OS
Guest
Storage
Windows OS
Storage
Host
Storage
Virtual Machine

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Storage options are either:
• Presented to Cluster nodes over SAS, Fibre Channel, iSCSI or SMB
• Require *1 drive letters or mount points
• 1-1 mapping between LUN and Cluster Volume
• Can be added as Cluster Shared Volumes (not FS)
1
2
Locally attached
Something else…
Serial Attached SCSI
Import generic
Fibre Channel iSCSI
Import generic
Import generic
SMB 3.0 Fileshare
Serial ATA is not
Supported on clusters
*1 Unless added to Cluster Shared Volumes
or if they are fileshares

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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
• SMB Multichannel
• Multi-network detect
• Transparent failover with (transparent) recovery
• Network bandwidth aggregation
• SMB Direct (SMB over RDMA)
• Lower CPU consumption (CPU offloading) –no context switching
• Low latency (client & server)
• High bandwidth utilization
• Reads and writes directly against memory of remote storage node
• Currently supports Infiniband, Internet Wide Area RDMA (iWARP)
and RDMA over Converged Ethernet (RoCE)

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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
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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Scale-Out File Server setup
• Build Windows Cluster
• Create Storage Pool of disks from storage enclosure/s
• Create Virtual Disk in Storage Pool
• Add Disk to Cluster Shared Volumes
• Add Scale-Out File Server Role
• Complete create File Share in File Server Role (in the CSV namespace)

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Why Hyper-V?
• Up to 64 Virtual CPUs
• Hyper-V Storage NUMU I/O (good for intensive IO workloads such
as SQL)
• VHDX disk format (from Windows 2012)
• 64TB Disks
• Power failure corruption protection (through logging updates)
• Storage reclamation through TRIM command support
• Storage QoS and Hyper-V IO Balancing*1
*1 IO Balancer currently only supports host-side storage (i.e. non-shared)

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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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Hyper-V Clustering
• Uses Windows Clustering (surprise surprise!)
• Each Hyper-V server is a cluster node
• Can therefore host Clustered Roles (Clustered Virtual Machine)
• Still act as a standalone Hypervisor
• Perform very fast live migration (secs) or quick migration
• Hyper-V Server is FREE.
• But virtualization rights aren’t!
• Consider Datacenter SKU

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PhysicalInfrastructure
Guest Clustering across Hyper-V hosts
• Shared Nothing Storage for Guest
Virtual Disks
• Windows Cluster is created across
guests
• Physical fabric provides services
• Virtualization benefits and SQL Instance
protection across multiple VMs/
Hypervisors
• Hypervisor level HA benefits (e.g.
“Shared Nothing Live Migration” in
Hyper-V
GuestCluster
SAN, Network and Storage
Fabric
Hypervisors
Guests

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Guest Clustering on a Hyper-V Cluster
• Can be thought of as a “Cluster on a
Cluster”. Clustered Virtual Machines
as deployed as roles in the cluster
• The SQL/ SSAS Failover Clustered
Instance can failover to each VM in
the Guest Cluster
• The Guest VM can benefit from live
fast migration failover to new Hyper-
V host without downtime to SQL FCI!
– Otherwise known as a Clustered
Live Migration” in Hyper-V
PhysicalInfrastructureGuestCluster
SAN, Network and Storage
Fabric
Hypervisors
Guests
Hyper-V Cluster
SQL Server Cluster

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NetFT
• Virtual adapter running over top
of NICs
• Can provide transparent
network failover if one NIC fails
• Autoconfiguring and hands free
• Provides performance filter
• Disabled by default
• Do not turn on for Hyper-V
Cluster nodes (otherwise
enable)

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In Summary…
• Failover Clustering and all its complexities is not getting easier but
it is getting more robust and richer.
• When combined with other MS Technologies such as Hyper-V and
Scalable File Server, SQL Failover Clustering provides *the*
definitive HA solution.
• Choose wisely which Cluster storage you use for Hyper-V and SQL
-should you use SMB 3.0 File Share/s from SO-FS OR CSV?
• Layering technologies can exacerbate the confusion!

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