Online Disk Extension & Windows 2008 R2 Dynamic Memory are Fully Supported for SQL Server

 

Several customers have recently asked about extending a disk online and the new Dynamic Memory Feature of Windows 2008 R2 Service Pack 1. 

 

It is fully supported to extend a Windows Disk ONLINE as of Windows 2008

 

Microsoft CSS team have recently updated KB304736 to explicitly confirm and support online disk extension on Windows 2008 and Windows 2008 R2.  In many cases online Windows extension will also work on Windows 2003 Service Pack 2 x64 Edition.

 

Here is a summary of the capabilities of Windows 2008 or higher

1.      Both Local disks and Shared Cluster disks can be extended Online

2.      Almost every modern SAN supports extending LUNs online, allocating this new space at the end of the disk and presenting this information to Windows

3.      The word “Online” means that the end-to-end service is preserved.  A disk may be extended with the cluster running, SAP & SQL Server running and on the system is on high load.  There is no necessity to wait for a period of low activity, though some customers choose to time such operations off peak

4.      Windows supports several kinds of disks.  MBR Disks are limited to 2TB in size.  In general GPT disks are recommended. 

 

5.      Both Basic Disks and Dynamic Disks can be extended online.  Dynamic Disks are not supported in a Windows Cluster, but there is no real use for Dynamic Disks with SQL Server Clusters. This blog explains the background on Basic and Dynamic Disks

6.      Windows 2008 & Windows 2008 R2 offer a simple way to extend a disk through the Disk Management GUI.  A command line tool diskpart.exe can also be used

7.      Windows allows for both extending and shrinking a disk (though we seldom find customers who need to shrink disks)

 

Windows 2003 based systems can usually extend a disk online.  Extending a disk on Windows 2003 needs testing prior to executing in a production environment.  This is because of the age of the Windows 2003 product and the fact not all drivers and components support online disk extension.  It is best to check with the SAN vendor and/or to test with the applications shutdown first.

 

SQL Server Fully Supports the Dynamic Memory Feature of Windows 2008 R2 Service Pack 1

 

Microsoft Windows Operating System includes an integrated embedded Virtualization Solution called Hyper-V in a similar manner as other operating systems such as UNIX.  AIX offers “Lpars”, HPUX provides “vPars” and a H/W level option called “nPars”.   

 

Hyper-V is fully supported both for SAP Application Servers (OSS Note 1409608)  and for SQL Server Database Servers.  In an earlier blog we discussed what is happening in detail on different Hardware platforms with Virtualization solutions and how this may impact performance. 

 

The performance capabilities of Hyper-V have increased over several generations of the product.  Today many customers have virtualized their non-productive SAP landscapes successfully.  Smaller customers less than ~2TB in database size have successfully moved their production systems to Virtual servers.

 

Microsoft has shipped Windows 2008 R2 Service Pack 1 to OEM distributors and this Service Pack will be released to the public next week.  Service Pack 1 offers Dynamic Memory for Hyper-V and many additional features.  

 

SQL Server Editions that support hot add memory can benefit from Windows Hyper-V Dynamic Memory.  Typically this is Enterprise Edition and Data Center Edition.

 

Details on Dynamic Memory for Hyper-V for SQL Server can be found in MS KB956893 – see Question 7.

 

Suggested reading:

SAP on Hyper-V Whitepaper  

Hyper-V Dynamic Memory Evaluation Guide

SQLOS Team Blog - Hyper-V Dynamic Memory  
Windows Virtualization Team Blog - Dynamic Memory