High availability (HA) is offered to protect each layer of the solution architecture, individually if desired. Following the N+1 model, additional ToR switches for LAN and iSCSI are added to the Network layer and stacked to provide redundancy as required, additional Compute and
Management hosts are added to their respective layers, Hyper-V clustering is introduced in the Management layer, and SQL is mirrored or clustered.
The HA options provides redundancy for all critical components in the stack while improving the performance and efficiency of the solution as a whole.
An additional switch is added at the Network layer, which will be configured with the original as a stack, and equally spreading each host’s network connections across both.
At the Compute layer with Local Tier 1 storage, an additional Hyper-V host is added to provide N+1 protection provided for pooled desktops and shared sessions. Failover clusters are utilized with Shared Tier 1 storage for personal desktop HA.
A number of enhancements occur at the Management layer, the first of which is the addition of another host. The Management hosts are configured in a failover cluster to allow live migration of management VMs. All applicable management server roles can be duplicated in the cluster and utilize native load balancing functionality if available. SQL will also receive greater protection through the addition and configuration of a SQL mirror with a witness.
5.7.1
Compute Layer
5.7.1.1
Local Tier 1
The optional HA bundle adds an additional host in the Compute and Management layers to
provide redundancy and additional processing power to spread out the load. The Compute layer in the Local Tier 1 model does not leverage shared storage so hypervisor HA does not provide a benefit here. To protect the Compute layer, with the additional Compute hosts added, connection brokers will be configured to provision reserve capacity. Care must be taken to ensure that VM provisioning does not exceed the capacity provided by additional hosts.
5.7.1.2
Shared Tier 1
For personal desktops in the Shared Tier 1 model, the Compute layer hosts will be configured in a failover cluster to insure availability in the event of a host failure. Care must be taken to ensure that VM provisioning does not exceed the capacity provided by additional hosts.
For pooled desktops and RDSH VMs in this model, the Compute layer hosts are provided using typical N+1 fashion but provided access to shared storage. An additional host is added to the pool and can be configured to absorb additional capacity or as a standby node should another fail.
Local Tier 1 – Compute HA
Pooled Desktop and RDSH VMs
Connection
Broker
N+1
Shared Tier 1 – Compute HA
Personal Desktop VMs
Failover Cluster
Manager
5.7.2
Management Layer
To implement HA for the Management layer for all models, we will also add an additional host but will add a few more layers of redundancy. The following will protect each of the critical infrastructure components in the solution:
The Management hosts will be configured in a failover cluster (Node and Disk Majority).
The storage volume that hosts the Management VMs will be upgraded to a CSV.
SQL Server mirroring is configured with a witness to further protect SQL.
An additional connection broker is added for active/active load balancing.
The management roles which support configurations storage in SQL will be protected via the SQL mirror. The Microsoft license server will be protected from host hardware failure and licensing grace period by default. If desired, it can be optionally protected further via the form of a cold stand-by VM residing on an opposing Management host.
Shared Tier 1 – Compute HA
Pooled Desktop and RDSH VMs
Connection
Broker
The following storage volumes are applicable in a two node Management layer HA scenario:
RDS
Volumes Host Size (GB)
RAID Storage
Array
Purpose File System CSV
Management 1 500 50 Tier 2 RDS VMs, File Server NTFS Yes
Management 2 500 50 Tier 2 RDS VMs, File Server NTFS Yes
SQL Data 2 100 50 Tier 2 SQL Data Disk NTFS Yes
SQL Logs 2 100 50 Tier 2 SQL Logs Disk NTFS Yes
SQL TempDB
Data 2 5 50 Tier 2 SQL TempDB Data Disk NTFS Yes
SQL TempDB
Logs 2 5 50 Tier 2 SQL TempDB Logs Disk NTFS Yes
SQL Witness 1 1 50 Tier 2 SQL Witness Disk NTFS Yes
Quorum 1 - 500MB 50 Tier 2 Hyper-V Cluster Quorum NTFS Yes
User Data - 2048 50 Tier 2 File Server NTFS No
User Profiles - 20 50 Tier 2 User profiles NTFS No
Templates/ ISO
- 200 50 Tier 2 ISO/ gold image storage
(optional)
NTFS Yes
vWorkspace Volumes Host Size
(GB) RAID Storage Array Purpose File System CSV
Management 1 500 50 Tier 2 vWorkspace
Infrastructure NTFS Yes
Management 2 500 50 Tier 2 vWorkspace
Infrastructure NTFS Yes
SQL Data 2 100 50 Tier 2 SQL Data Disk NTFS Yes
SQL Logs 2 100 50 Tier 2 SQL Logs Disk NTFS Yes
SQL TempDB
Data 2 5 50 Tier 2 SQL TempDB Data Disk NTFS Yes
SQL TempDB
Logs 2 5 50 Tier 2 SQL TempDB Logs Disk NTFS Yes
SQL Witness 1 1 50 Tier 2 SQL Witness Disk NTFS Yes
Quorum 1 - 500MB 50 Tier 2 Hyper-V Cluster Quorum NTFS Yes
User Data - 2048 50 Tier 2 File Server NTFS No
User Profiles - 20 50 Tier 2 User profiles NTFS No
Templates/ ISO
- 200 50 Tier 2 ISO/ gold image storage
(optional)
5.7.3
SQL Server High Availability
HA for SQL will be provided via a three server synchronous mirror configuration that includes a witness (High safety with automatic failover). This configuration will protect all critical data stored within the database from physical server as well as virtual server problems. DNS will be used to control access to the active SQL server, please refer to section 5.7.1 for more details. Place the principal VM that will host the primary copy of the data on the first Management host. Place the mirror and witness VMs on the second or later
Management hosts. Mirror all critical databases to provide HA protection.
The following article details the step-by-step mirror configuration: LINK Additional resources can be found in TechNet: LINK1 and LINK2
Please refer to the following Dell Software support article for more information about vWorkspace SQL Server mirror support: LINK
5.7.4
Disaster Recovery and Business Continuity
DR and BC can be achieved natively via Hyper-V Replicas. This technology can be used to replicate VMs from a primary site to a DR or BC site over the WAN asynchronously. Hyper-V Replicas are unbiased as to underlying hardware platform and can be replicated to any server, network, or storage provider. Once the initial replica is delivered from the primary site to the replica site, incremental VM write changes are replicated using log file updates. Multiple recovery points can be stored and maintained, using snapshots, to restore a VM to a specific point in time.
5.8