Guaranteeing continuous availability of applications and
services is essential in today’s business world. If users can’t use the
applications they need, the productivity of your business will be
affected. And if customers can’t access the services your organization
provides, you’ll lose their business. Although previous versions of
Windows Server have included features like Failover
Clustering and NLB that help you ensure the availability of
business-critical applications and services, Windows Server 2012 adds a
number of improvements that can greatly help ensure application uptime
and minimize service disruptions.
Key availability improvements include enhancements to Failover
Clustering such as greater scalability, simplified updating of cluster
nodes, and improved support for guest clustering. The new SMB
3.0 Transparent Failover capability lets you perform maintenance on
your cluster nodes without interrupting access to file shares on your
cluster. Storage
Migration now allows you to transfer the virtual disks and
configuration of VMs to new locations while the VMs are still running. Windows
NIC Teaming now provides an in-box solution for implementing fault
tolerance for the network adapters of your servers. Improvements to
Chkdsk greatly reduce potential downtime caused by file system
corruption on mission-critical servers. Easy conversion between
installation options provides increased flexibility for how you
configure servers in your environment, whereas Features On Demand lets
you install Server Core features from a remote repository instead of
the local disk. And DHCP failover improves resiliency by allowing you
to ensure continuous availability of Dynamic Host Configuration Protocol (DHCP) services to clients on your network.
In the following sections, we’ll dig deeper into each of these
capabilities and features. And we’ll continue to benefit from the
insights and tips from insiders working at Microsoft and from select
experts who have worked with Windows Server 2012 during the early
stages of the product release cycle.
1. Failover Clustering enhancements
Failover Clustering is a feature of Windows Server that provides high availability
for server workloads. File servers, database servers, and application
servers are often deployed in failover clusters so that when one node
of the cluster fails, the other nodes can continue to provide services.
Failover Clustering also helps ensure workloads can be scaled up and
out to meet the demands of your business.
Although the Failover
Clustering feature of previous versions of Windows Server provided a
robust solution for implementing high-availability solutions, this
feature has been significantly enhanced in Windows Server 2012 to
provide even greater scalability, faster failover, more flexibility in
how it can be implemented, and easier management. The sections that
follow describe some the key improvements to Failover Clustering found
in Windows Server 2012. Note that some other cluster-aware features,
such as concurrent Live Migrations and Hyper-V Replica.
Failover Clustering in Windows Server 2012 now provides
significantly greater scalability compared to Windows Server 2008 R2 by
enabling you to do the following:
-
Scale out your environment by creating clusters with up to a maximum
of 64 nodes, compared to only 16 nodes in the previous version.
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Scale up your infrastructure by running up to 4,000 VMs per cluster and up to 1,024 VMs per node.
These scalability enhancements make Windows Server 2012 the platform
of choice for meeting the most demanding business needs for high
availability.
CSV2 and scale-out file servers
Version 1 of Cluster Shared Volumes (CSV) was introduced in Windows Server 2008 R2 to allow multiple cluster
nodes to access the same NTFS-formatted volume simultaneously. A number
of improvements have been made to this feature in Windows Server 2012
to make it easier to configure and use a CSV and to provide increased
security and performance.
For example, a CSV now appears as a single consistent file namespace called the CSV File System (CSVFS), although the underlying file system technology being used remains NTFS.
CSVFS also allows direct I/O for file data access and supports sparse
files, which enhances performance when creating and copying VMs. From
the security standpoint, a significant enhancement is the ability to
use BitLocker Drive Encryption to encrypt both traditional failover
disks and CSVs. And it’s also easier now to back up and restore a CSV
with in-box support for CSV backups provided by Windows Server Backup.
Backups of CSV volumes no longer require redirected I/O in version 2.
The volume snapshots can be taken on the host that currently owns the
volume, unlike version 1, where they were taken on the node requesting
the backup. Configuring a CSV can now be performed with a single
right-click in the Storage pane of Failover Cluster Manager.
Scale-out file servers are built on top of the Failover
Clustering feature of Windows Server 2012 and the SMB 3.0 protocol
enhancements. Scale-out file servers allow you to scale the capacity of
your file servers upward or downward dynamically as the needs of your
business change. This means you can start with a low-cost solution such
as a two-node file server, and then later add additional nodes (to a
maximum of four) without affecting the operation of your file server.
Scale-out file servers can be configured by starting the High
Availability Wizard from Failover Cluster Manager. Begin by selecting
File Server from the list of cluster roles (formerly called clustered
services and applications):
Then, on the next page of the wizard, select the File Server For Scale-Out Application Data option, as shown here, and continue through the wizard:
When the wizard executes, a series of steps is performed to create the scale-out file server. These steps are summarized in a report that the wizard generates:
Scale-out file servers have a few limitations that general-use file servers don’t have. Specifically, scale-out file servers don’t support:
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File Server Resource Management (FSRM) features like Folder Quotas, File Screening, and File Classification
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Distributed File Services Replication (DFS-R)
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NFS
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Data deduplication
