With Windows Server 2012 (formerly “Windows Server 8”) on the horizon and many IT shops mulling upgrades, it’s more likely upgrades to Server 2012 will be incremental rather than all-at-once. It’s likely that those with infrastructure built on top of Windows Server will have both Server 2012 and older versions of Server running side-by-side for some time.
Given that, here are a few answers to common questions about how the new and older versions of Windows Server might have coexistence issues.
Can I run Windows Server 2012 systems in a cluster with earlier versions of Windows Server?
The short answer is “no.” There are several reasons for this, not least of which are the major improvements in the way clustering is managed and deployed across servers in Windows Server 2012. The new clustering features aren’t backward-compatible with earlier versions of Windows Server, so clusters can’t be upgraded in a “rolling” fashion; each node in a cluster has to be evicted from the cluster, upgraded to Windows Server 2012 and added to a whole new cluster of 2012-only servers.
Here are some of the key new clustering features in Windows Server 2012, which will not be supported by earlier versions of the operating system:
Storage migration. This allows cluster-managed VMs to be live-migrated to a new location while the VM is up and running, in much the same manner as VMware’s vMotion.
Clustered shared volumes. This feature is not new to Server 2012 -- it was introduced in Windows Server 2008 R2 -- but it’s been revised and expanded, and the expanded functionality is not available for previous versions of Server. Multiple nodes in the same cluster can share the same file system, which allows a VM hosted on any node in that cluster to be migrated to any other node on that cluster.
Cluster-aware updating (CAU). Updates to machines in a Windows Server 2012 cluster can be applied automatically in a rolling fashion. This way, the whole cluster remains online during the process. Plugins that talk to an API expand CAU’s behavior.
There are many other new features, but to use them uniformly across a cluster requires a cluster-wide upgrade to Windows Server 2012.
What do I need to know about using file shares between Windows Server 2012 and earlier versions of Windows Server?
Windows Server 2012 uses the new SMB 3.0 protocol (originally SMB 2.2) for establishing file shares between Windows systems.
SMB 3.0 clients will always attempt to negotiate the highest possible level of the protocol with any peer it connects with, so if you establish a share between Windows Server 2012 and earlier versions of Windows Server, the connection will be negotiated according to whatever level of SMB is available on the other server. Microsoft TechNet blogger Jose Barreto has a post with a chart that spells out the highest grade of SMB available to a connection negotiated between any two editions of Windows.
SMB 3.0's new features are only available to other Windows Server 2012 or Windows 8 systems. Some of the new features include:
Scale-out. The same folder can be shared from multiple nodes in a cluster for the sake of failover, better use of bandwidth, dynamic capacity scaling, load balancing and fault tolerance.
Multichannel support. Any multiple, redundant network links between SMB peers can be used to accelerate the connection.
End-to-end encryption. Data sent between SMB 3.0 peers is encrypted by default.
VSS support. SMB shares are now covered by volume shadow copies as well, so data on file shares can also be backed up and restored through any VSS-aware software.
SMB Direct. Servers that use RDMA-capable network adapters can enjoy high-speed memory-to-memory data transfers with far less CPU usage and latency than conventional copy operations.
SMB directory leasing. This feature reduces latency for documents accessed via the Branch Cache feature, by locally caching more of the metadata associated with the document and reducing the amount of roundtrips to the original server.
Note that if you have a mixed infrastructure where all the clients and servers use SMB 2 or better -- Windows Vista on the client side, Windows Server 2008 on the server side -- disable the use of SMB 1.x with the PowerShell command Set-SmbServerConfiguration –EnableSMB1Protocol $false. Disabling SMB 1.x reduces the potential attack surface for the server. If the protocol isn't in use, it's best to disable it to prevent a possible future exploit from being used on it.
What Windows Server features are being deprecated in Windows Server 2012?
Some features in Windows Server are no longer supported as of Windows Server 2012, or are in the process of being removed. Most of these deprecations only involve code or applications that run directly on the new OS, rather than interoperations with other editions. That said, there are exceptions especially if, for instance, you have an older application that expects the same behavior when it tries to interoperate with the newer version of Server.
Here’s a list of some of the major deprecations and feature removals in Windows Server 2012 (with more listed at TechNet), which may impact cross-server compatibility or applications running on other servers:
Clustering. 32-bit cluster resource DLLs are being deprecated and should be replaced with their 64-bit counterparts whenever possible. Also, if you have any programs that use the Cluster Automation Server (MSClus) COM API, be aware that this API is now only available via an optional component named FailoverCluster-AutomationServer, which isn’t installed by default.
Databases. 16- and 32-bit ODBC support has been removed, as have ODBC and OLEDB drivers for Oracle and Jet Red databases. (Use vendor-supplied database connectors.) ODBC/OLEDB support is also being canned for any versions of SQL Server beyond 2000; for those editions of SQL Server and higher, use SQL Native Client instead. Finally, no version of SQL Server earlier than 7.0 is supported at all. It’s unlikely that anyone is still running SQL Server 6.5 or earlier, but any attempts to connect to a SQL Server 6.5 (or earlier) instance from Windows Server 2012 will generate an error.
UNIX. Many UNIX subsystem features are being deprecated or removed. Microsoft entire SUA POSIX subsystem is being deprecated, along with the line printer daemon protocol that is often used by UNIX clients. As a general replacement for Microsoft’s UNIX features consider using the Cygwin or MinGW, open source tools and APIs that are maintained entirely apart from Windows’s own evolution.
WMI. Many individual WMI providers are being removed or deprecated: SNMP (because SNMP itself is deprecated); the WMI provider for Active Directory (eclipsed by PowerShell), and the Win32_ServerFeature API.
Finally, the Windows Help application (winhlp32.exe) has also been removed although it has not shipped with Windows Server since Windows Server 2008. What’s more, no add-on version of the Windows Help program is being supplied through Microsoft as a download, as it did with previous versions of Windows that omitted Windows Help. (However, a Windows Help edition for the client edition of Windows 8 will be made available later, which should do the job.)
ABOUT THE AUTHOR
Serdar Yegulalp has been writing about computers and IT for more than 15 years for a variety of publications, including InformationWeek and Windows Magazine.
This was first published in June 2012