Further. Forward. Faster.
6. Microsoft Private Cloud Solution for SAP:
Configuration of Cluster Shared Volumes,
VHDX, Disks & LUNs
Authors
Cameron Gardiner, Microsoft Senior Program Manager – SAP
Technical Reviewers
Juergen Thomas, Principal Lead Program Manager
Hermann Daeubler, Microsoft Senior Program Manager – SAP
Summary
This document provides guidance for customers and partners to deploy SAP on a Microsoft Private Cloud
Solution for SAP. This chapter discusses the Configuration of Cluster Shared Volumes, VHDX, Disks & LUNs
CSV, VHDX & LUNs
Table of Contents
Table of Contents ........................................................................................................ 2
1
Summary ................................................................................................................ 4
2
Example Configuration – SQL Server VM ........................................................... 5
2.1 SQL SERVER VM CONFIGURATION DETAILS ......................................................................................... 5
2.1.1
Physical Server.............................................................................................................................. 5
2.1.2
Virtual Machine ............................................................................................................................ 5
2.1.2.1 Roles & Features Required for SQL Server ................................................................... 5
2.1.2.2 Windows Server 2012 Server Core................................................................................... 6
2.1.3
SQL Server Named Instance & Datafile Configuration ................................................. 6
2.1.4
Cluster Shared Volume & Virtual Hard Disk ..................................................................... 8
2.1.5
SAN Configuration...................................................................................................................... 8
3
Example Configuration – SAP Application Server VM ...................................10
3.1.1
Physical Server........................................................................................................................... 10
3.1.2
Virtual Machine ......................................................................................................................... 10
3.1.2.1 Roles & Features Required for SAP Application Server ........................................ 10
3.1.2.2 Windows Server 2012 Server Core................................................................................ 10
3.1.3
SAP Application Server Disk Configuration.................................................................... 10
3.1.4
Cluster Shared Volume & Virtual Hard Disk .................................................................. 13
3.1.5
SAN Configuration................................................................................................................... 13
4
Example Configuration – SAP ASCS SPOF VM ................................................15
4.1.1
Physical Server........................................................................................................................... 15
4.1.2
Virtual Machine ......................................................................................................................... 15
4.1.2.1 Roles & Features Required for SAP Application Server ........................................ 15
4.1.2.2 Virtual Machine Affinity..................................................................................................... 15
4.1.2.3 Windows Server 2012 Server Core................................................................................ 15
4.1.3
SAP ASCS Cluster Disk Configuration .............................................................................. 16
4.1.4
Cluster Shared Volume & Virtual Hard Disk .................................................................. 18
4.1.5
SAN Configuration................................................................................................................... 18
4.1.6
Shared Disk for SAP ASCS .................................................................................................... 18
4.1.6.1 iSCSI .......................................................................................................................................... 18
4.1.6.2 Virtual Fibre Channel (vHBA)........................................................................................... 18
5
Cluster Shared Volumes .....................................................................................21
5.1 HOW MANY VIRTUAL MACHINES PER CSV?...................................................................................... 21
5.2 RENAMING CSV PATHS ......................................................................................................................... 21
5.3 CLUSTER SHARED VOLUME CACHE ...................................................................................................... 22
5.3.1
CsvEnableBlockCache ............................................................................................................. 22
5.3.2
SharedVolumeBlockCacheSizeInMB ................................................................................. 22
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5.3.3
6
How to Set CSV Cache ........................................................................................................... 22
Virtual Hard Disk Configuration - VHDX .........................................................23
6.1 VHDX TYPES ........................................................................................................................................... 23
6.1.1
Fixed, Dynamic & Differencing ........................................................................................... 23
6.1.2
Windows 2008 VHD vs. Windows Server 2012 VHDX................................................ 23
6.2 MBR, GPT, NTFS AUS SIZE AND OTHER OPTIONS .......................................................................... 23
7
Appendix 2 – Links Page ....................................................................................25
SAP on Microsoft Private Cloud
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CSV, VHDX & LUNs
1 Summary
Windows Server 2012 Hyper-V 3.0 is a powerful integrated Virtualization platform. Microsoft Private
Cloud for SAP systems is a tailored solution optimized and simplified to enable customers and
partners to quickly deploy SAP on Hyper-V.
Configuration of SQL Server datafiles and logfiles, Virtual Hard Disks and placing these onto Cluster
Shared Volumes is often confusing for customers.
This document illustrates and simplifies this configuration through diagrams and tables. Customers
are encouraged to copy the Visio diagrams and Excel spreadsheets contained in this document and
customize to their specific configuration.
There are mandatory requirements that must be followed:
1. Windows Server 2012 Hyper-V 3.0 physical cluster servers must be 2 processor systems with
a minimum of 384GB RAM. 384GB is strictly mandatory and customers must not attempt to
deploy this reference architecture on systems with less than 384GB RAM
2. SQL Server systems require different numbers of datafiles depending on the size of the
system.
Small sized systems: 4 data files.
Medium sized systems: 8 data files.
Larger sized systems: 16 data files.
Xtra large sized systems: 32 for server with more than 160 or more Logical Processors.
3. SQL Server databases only require 1 large log file per database
Small systems start with Logfile size 5 - 10 GB
Medium systems start with Logfile size 50 - 100 GB
Large systems start with Logfile size 300 - 500 GB
4. Tempdb must be configured with at least 4 datafiles and one log file. These should be “colocated” on the same Virtual Hard Disks and Cluster Shared Volumes as the SAP DB datafiles
5. Large busy systems such as ECC, BW, CRM and SCM can have up to 4 SAP DB datafiles per
Virtual Hard Disk
6. Very small SAP systems such as non-productive EP, XI, GCR or Solman may consolidate many
databases onto a single VM. Each SAP component requires a separate Named Instance of
SQL Server. Small systems with very low workload may consolidate all SAP DB datafiles onto
a set of VHDXs
7. SQL Server AlwaysOn is the preferred method of achieving high availability for the database
layer. Traditional SQL Server clustered are supported for reverse compatibility reasons only
8. A single large C: Drive no less than 120GB must be created for SAP application servers or SAP
ASCS cluster servers. Do not partition the Virtual Hard Disk into C:, D:, E: drives
9. SAP and SQL Servers are not to be used as file servers
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CSV, VHDX & LUNs
2 Example Configuration – SQL Server VM
SAP on Microsoft Private Cloud reference deployment can be decomposed into several simple
layers thereby allowing customers and partners to correctly configure Microsoft Private Cloud
infrastructure for best performance and availability.
The layers are:
1. Physical Servers running Windows Server 2012 Datacenter, Hyper-V and Windows Cluster
with Cluster Shared Disks
2. Virtual Machines running Windows Server 2012, SQL Server 2012 SP1 or higher and SAP
Host Monitoring Agent
3. SQL Server Named Instance running one or more SAP databases with a specified number of
datafiles, tempdb files and log file
4. Cluster Shared Volumes holding one or more sets of Virtual Hard Disk (VHDX) files
5. Physical SAN Layer contains physical disks aggregrated and presented to the Physical
Servers running Windows Server 2012 as a number of LUNs
2.1 SQL Server VM Configuration Details
SQL Server Virtual Machines require some specific configuration to achieve good performance.
The following sections should be reviewed in conjuction with the diagram on the following page.
This section depicts a dedicated SQL Server such as that used on a three tier system. When
installing two tier systems (SQL Server and SAP on the same VM) simply combine the configuration
details in section 2 and 3 of this document.
2.1.1 Physical Server
See the Chapter 6 and 9 for information on the physical server configuration
2.1.2 Virtual Machine
Windows Server 2012 Standard Edition or greater should be used for running SQL Server.
See the Sizing Chapter for information on the Virtual Machine sizing.
2.1.2.1
Roles & Features Required for SQL Server
If a SQL Server VM is part of an AlwaysOn HA/DR configuration then Windows Cluster Feature must
be installed. Otherwise only the minimum Roles and Features should be installed.
SQL Server Installer required .Net 4.0 or 3.5.1.
SAP Software Provisioning Manager (SWPM) may install File Services Feature onto a dedicated SQL
Server during installation. This is not required for the operation of the SAP system and should be
removed once SWPM procedure is completed.
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2.1.2.2
Windows Server 2012 Server Core
To reduce patching requirements it is supported to run SQL Server on a Windows Server 2012 core
server1
See the Security Chapter for more information on hardening the Guest Virtual Machines
2.1.3 SQL Server Named Instance & Datafile Configuration
To allow consolidation of multiple databases onto the SQL Server VM, SQL Server should be installed
as a Named Instance. Larger SQL Server systems might require a dedicated VM.
Small sized systems: 4 data files.
Systems usually run on servers which have between 4 and 8 Logical Processors2.
Medium sized systems: At least 8 data files.
Systems usually run on servers which have between 8 and 16 Logical Processors.
Larger sized systems: A minimum of 16 data files.
Systems which today run on hardware between 16 and 120 Logical Processors.
Xtra large sized systems: 32 for server with more than 160 or more Logical Processors.
Small systems start with Logfile size 5 - 10 GB
Medium systems start with Logfile size 50 - 100 GB
Large systems start with Logfile size 300 - 500 GB
Only one Logfile should be created – SQL Server will only use one Logfile at one time
Check and eventually set autogrowth rate to 10%
To achieve a good balance between performance and administration it is recommended to place
four SAP DB datafiles per Virtual Hard Disk. Tempdb files can be placed on the same Virtual Hard
Disk as the SAP DB datafiles/logfile.
Traditional Clustering of SQL Server is supported on Microsoft Private Cloud for SAP via the use of
the vHBA or iSCSI. To achieve High Availability at the database level SQL Server 2012 AlwaysOn is
highly recommended. Support for traditional SQL Server clustering is for reverse compatibility
reasons only. New systems should be installed with SQL Server AlwaysOn. See the High Availability
Chapter for more information
If SQL Server is running on Windows Core a “management station” with SQL Server
Management Studio must be available as well as remote server management
1
http://blogs.msdn.com/b/saponsqlserver/archive/2010/09/28/windows-2008-r2-groupsprocessors-sockets-cores-threads-numa-nodes-what-is-all-this.aspx
2
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CSV, VHDX & LUNs
VM Host Name
Home Node
(1 – 5)
DB File Path on VM
Virtual Hard Disk Name
Cluster Shared Volume VHDX Path on Host
SAN LUN
CSV Cache
sapeccdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapdb1
sapsolman1
sapdb2
sapdb2
sapdb2
sapdb2
sapdb2
sapdb2
sapdb2
sapdb2
sapdb2
sapdb2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
3
3
3
3
3
3
3
3
3
3
OS disk C:\Program Files\SQLServer
F:\ECCDATA1\ECCDATA1.mdf
F:\ECCDATA2\ECCDATA2.ndf
F:\ECCDATA3\ECCDATA3.ndf
F:\ECCDATA4\ECCDATA4.ndf
G:\ECCDATA5\ECCDATA5.ndf
G:\ECCDATA6\ECCDATA6.ndf
G:\ECCDATA7\ECCDATA7.ndf
G:\ECCDATA8\ECCDATA8.ndf
H:\ECCDATA9\ECCDATA9.ndf
H:\ECCDATA10\ECCDATA10.ndf
H:\ECCDATA11\ECCDATA11.ndf
H:\ECCDATA12\ECCDATA12.ndf
I:\ECCDATA13\ECCDATA13.ndf
I:\ECCDATA14\ECCDATA14.ndf
I:\ECCDATA15\ECCDATA15.ndf
I:\ECCDATA16\ECCDATA16.ndf
L:\ECCLOG1\ECCLOG1.ldf
F:\TEMPDB1\TEMPDB1.mdf
G:\TEMPDB2\TEMPDB2.ndf
H:\TEMPDB3\TEMPDB3.ndf
I:\TEMPDB4\TEMPDB4.ndf
L:\ TEMPLOG1\TEMPLOG1.ldf
OS disk C:\Program Files\SQLServer
F:\SLMDATA1\SLMDATA1.mdf
G:\SLMDATA2\SLMDATA2.ndf
H:\SLMDATA3\SLMDATA3.ndf
I:\SLMDATA4\SLMDATA4.ndf
L:\SLMLOG1\SLMLOG1.ldf
F:\TEMPDB1\TEMPDB1.mdf
G:\TEMPDB2\TEMPDB2.ndf
H:\TEMPDB3\TEMPDB3.ndf
I:\TEMPDB4\TEMPDB4.ndf
L:\ TEMPLOG1\TEMPLOG1.ldf
sapdb1_ECC_C_DISK.VHDX
sapdb1_ECC_F_DISK.VHDX
sapdb1_ECC_F_DISK.VHDX
sapdb1_ECC_F_DISK.VHDX
sapdb1_ECC_F_DISK.VHDX
sapdb1_ECC_G_DISK.VHDX
sapdb1_ECC_G_DISK.VHDX
sapdb1_ECC_G_DISK.VHDX
sapdb1_ECC_G_DISK.VHDX
sapdb1_ECC_H_DISK.VHDX
sapdb1_ECC_H_DISK.VHDX
sapdb1_ECC_H_DISK.VHDX
sapdb1_ECC_H_DISK.VHDX
sapdb1_ECC_I_DISK.VHDX
sapdb1_ECC_I_DISK.VHDX
sapdb1_ECC_I_DISK.VHDX
sapdb1_ECC_I_DISK.VHDX
sapdb1_ECC_L_DISK.VHDX
sapdb1_ECC_F_DISK.VHDX
sapdb1_ECC_G_DISK.VHDX
sapdb1_ECC_H_DISK.VHDX
sapdb1_ECC_I_DISK.VHDX
sapdb1_ECC_L_DISK.VHDX
sapdb2_ECC_C_DISK.VHDX
sapdb2_SLM_F_DISK.VHDX
sapdb2_SLM_G_DISK.VHDX
sapdb2_SLM_H_DISK.VHDX
sapdb2_SLM_I_DISK.VHDX
sapdb2_SLM_L_DISK.VHDX
sapdb2_SLM_F_DISK.VHDX
sapdb2_SLM_G_DISK.VHDX
sapdb2_SLM_H_DISK.VHDX
sapdb2_SLM_I_DISK.VHDX
sapdb2_SLM_L_DISK.VHDX
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume1\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume1\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume1\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume1\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume2\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume2\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume2\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume2\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume3\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume3\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume3\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume3\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume4\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume4\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume4\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume4\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume5\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume1\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume2\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume3\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume4\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume5\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume1\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume2\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume3\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume4\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume5\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume1\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume2\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume3\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume4\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume5\SLM\<vm name>\Virtual Hard Disks\
6
1
1
1
1
2
2
2
2
3
3
3
3
4
4
4
4
5
1
2
3
4
5
6
1
2
3
4
5
1
2
3
4
5
Yes
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
No
No
No
No
No
No
No
No
No
No
Table shows two SAP systems running on separate VMs on a 5 node Microsoft Private Cloud Infrastructure.
ECC 6.5 system SID = ECC and a Solution Manager system SID = SLM. ECC 6.6 is a large database and requires 16 datafiles. The Solution
Manager system is small and only requires four datafiles. To ensure IO is balanced on the Microsoft Private Cloud Infrastructure for SAP every
system must have a minimum of four VHDX, one placed on each of the four Cluster Shared Volumes
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2.1.4 Cluster Shared Volume & Virtual Hard Disk
Windows Server 2012 Cluster Shared Volumes can support many VHDXs and many VHDXs from
different VMs. 10-25 Virtual Machines can share the same set of CSV without performance impact
when configured correctly. To balance SQL Server IO across sufficient LUNs the Microsoft Private
Cloud reference architecture for SAP systems required four CSVs for SQL Datafiles and one CSV for
SQL Log files. It is not supported to place all SQL Datafiles and the Log file on one single CSV
(leveraging only one LUN).
Up to four SAP database SQL Datafiles can be placed on one Virtual Hard Disk (VHDX). Distributing
SQL Server datafiles onto separate VHDX on separate Cluster Shared Volumes will improve IO
performance and ensure that the IO load on all the Cluster Shared Volumes is balanced. A small SAP
system with only 4 datafiles should have one datafile per VHDX. One VHDX should be placed on
each Cluster Shared Volume thereby balancing the IO load on the Cluster Shared Volumes and LUNs.
A small SAP system with only 8 datafiles should have two datafile per VHDX. One VHDX should be
placed on each Cluster Shared Volume thereby balancing the IO load on the Cluster Shared Volumes
and LUNs.
SAP Landscapes normally have a number of very low SQL transaction volume systems such as
Enterprise Portal, GRC, XI, Solution Manager etc. The load on SQL Server is very small. Such systems
can be consolidated as multiple Named Instances on one Virtual Machine. In such cases it is possible
to consolidate 4-6 SAP components such as EP, GRC etc onto one VM provided the SQL Server
workload is observed to be very low. In this scenario each SAP component has its own SQL Server
Named Instance with 4-6 Named Instances consolidated on one VM. The datafiles for all of the
Named Instances can be consolidated into the four Virtual Hard Disks (F:, G:, H: and I:) for SQL
datafiles and one Virtual Hard Disk for logfiles.
2.1.5 SAN Configuration
Each Cluster Shared Volume requires a separate LUN at the SAN level. The LUNs for the CSV must
be presented to all nodes in the Hyper-V 3.0 cluster.
RAID 5 (or similar) is suitable for the Cluster Shared Volumes holding the Virtual Hard Disks that in
turn hold SQL Server Datafiles.
RAID 1 (or similar) should be used for the Cluster Shared Volumes holding the Virtual Hard Disks
that in turn hold SQL Server Log.
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MS Private Cloud Physical Layer
Windows 2012 Hyper-V 3.0 Cluster
VM Layer
Large VM = 16vCPU, 192GB vRAM
In this example this VM is only running a
single SQL Server instance with a single
database for a 1,500 concurrent user
ECC 6.6 system. DB size is 1TB fully
PAGE compressed
SAP DB Layout: 16 datafiles, 1x 200GB Log
Tempdb Layout: 4x 1GB datafiles, 1x 1GB Log
VHDX: 4 SQL datafiles per VHDX
CSV: 5 CSV shared by all SAP systems
LUN: 5x Data + Log LUN
2TB
ECC 6.5
DB
Datafile Layer
Datafile 9
Datafile 5 Datafile 6
Datafile 1 Datafile 2
Datafile 3 Datafile 4
Datafile 7 Datafile 8
tempdb 1
tempdb 2
sapdb1_ECC_F_DISK.VHDX
sapdb1_ECC_G_DISK.VHDX
Datafile
13
Datafile
10
Datafile
11
Datafile
15
Datafile
12
Datafile
14
Datafile
16
tempdb 4
tempdb 3
sapdb1_ECC_H_DISK.VHDX
sapdb1_ECC_I_DISK.VHDX
SAP DB
Log File
200GB
Temp log
sapdb1_ECC_L_DISK.VHDX
Virtual Hard Disk -> CSV Layer
C:\ClusterStorage\
Volume1
C:\ClusterStorage\
Volume2
C:\ClusterStorage\
Volume3
C:\ClusterStorage\
Volume4
C:\ClusterStorage\
Volume5
{
LUN 1
LUN 2
SAP on Microsoft Private Cloud
LUN 3
LUN 4
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LUN 5
SAN Layer
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3 Example Configuration – SAP Application Server VM
SAP on Microsoft Private Cloud reference deployment can be decomposed into several simple
layers thereby allowing customers and partners to correctly configure Microsoft Private Cloud
infrastructures.
SAP Application Server Virtual Machines require some specific configuration to achieve good
performance. The following sections should be reviewed in conjuction with the diagram on the
following page. This section depicts a dedicated SAP Application Server (non-clustered) such as
that used on a three tier system. When installing two tier systems (SQL Server and SAP on the
same VM) simply combine the configuration details in section 2 and 3 of this document.
3.1.1 Physical Server
See the Sizing Chapter for information on the physical server configuration
3.1.2 Virtual Machine
Windows Server 2012 Standard Edition or greater should be used for running a SAP Application
Server.
See the Sizing Chapter for information on the Virtual Machine sizing.
3.1.2.1
Roles & Features Required for SAP Application Server
The SAP Application Server requires the File Services Role in order to share \SAPLOC.
Roles or Features are typically required
3.1.2.2
No other
Windows Server 2012 Server Core
It is not supported at this time to run the SAP application server on Windows Server Core or Hybrid.
The only supported “Shell” is Full GUI.
See the Security Chapter for more information on hardening the Guest Virtual Machines
3.1.3 SAP Application Server Disk Configuration
The SAP ABAP and Java Application Servers do not cause significant IO on their own file systems.
Typically the IO activity on the \usr\sap file system is limited to writing trace files and other activity.
The vast majority of the IO on a SAP system is caused by the Database.
In order to simplify the configuration one large C: Drive should be used to hold the following
components:
1. Windows Server 2012 Guest Operating System
2. Pagefile.sys
3. C:\usr\SAP\<SID>\<instance>
4. SAP Host Agent C:\Program Files\SAP\HostCtrl\exe
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Typically 120GB Virtual Hard Disk partitioned into one single large C: Drive is sufficient for this
purpose. It is highly unlikely that the disk would ever fill up on a SAP application server as no files
are stored on SAP Application Servers.
In the majority of cases where a file system has filled up the root cause has been the use of a SAP or
SQL Server as a File Server. SAP and SQL Servers must never be used as File Servers. Chapter 4
discusses security in detail. It is a mandatory requirement of this deployment architecture that File
Sharing is blocked by the Windows Firewall, preventing any of the SAP on Microsoft Private Cloud
infrastructure from being used as a File Server.
SAP ABAP programs that download content to a text file should be configured to write to ABAP
Logical File Names (defined in transaction FILE) on a separate dedicated File Server. SAP and SQL
Servers are not to be used as File Servers under any circumstance.
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CSV, VHDX & LUNs
VM Host Name
Home Node
(1 – 5)
SAP Path on VM
Virtual Hard Disk Name
Cluster Shared Volume VHDX Path on Host
SAN LUN
CSV Cache
sapapp1
1
C:\usr\SAP\ECC\D00
C:\usr\SAP\ECC\D01
C:\Program
Files\SAP\HostCtrl\exe
C:\Windows
C:\Pagefile.sys
C:\usr\SAP\SLM\D00
??Host Agent Path??
C:\Windows
C:\Pagefile.sys
sapapp1_ECC_C_DISK.VHDX
sapapp1_ECC_C_DISK.VHDX
sapapp1_ECC_C_DISK.VHDX
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
6
6
6
Yes
Yes
Yes
sapapp1_ECC_C_DISK.VHDX
sapapp1_ECC_C_DISK.VHDX
sapapp2_SLM_C_DISK.VHDX
sapapp2_SLM_C_DISK.VHDX
sapapp2_SLM_C_DISK.VHDX
sapapp2_SLM_C_DISK.VHDX
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\SLM\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\SLM\<vm name>\Virtual Hard Disks\
6
6
6
6
6
6
Yes
Yes
Yes
Yes
Yes
Yes
sapapp2
Table shows two SAP systems running on separate VMs on a 5 node Microsoft Private Cloud Infrastructure.
ECC 6.6 system SID = ECC and a Solution Manager system SID = SLM. ECC 6.6 has two application server instances running on one VM3. The
Solution Manager system has only one instance. The Virtual Hard Disks for the SAP application servers can all reside on a dedicated Cluster
Shared Volume (using its own dedicated SAN LUN).
3
For HA reasons it is always recommended to have multiple VMs for each production application component
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3.1.4 Cluster Shared Volume & Virtual Hard Disk
Windows Server 2012 Cluster Shared Volumes can support many VHDXs and many VHDXs from
different VMs. 10-25 Virtual Machines can share the same set of CSV without performance impact
when configured correctly.
If more than one SAP Component (eg. ECC, CRM, PI and Solman) is installed on a single SAP
application server then the VHDX file holding the C: drive may need to be increased in size. The
VHDX file should have the naming convention:
C:\ClusterStorage\Volume6\<SID>\<vm hostname>\Virtual Hard Disks\<vm
hostname>_<SID>_C_DISK.VHDX
The value for SID on SAP application servers with multiple components should be the SID of the
first system installed.
3.1.5 SAN Configuration
A single Cluster Shared Volume on a dedicated single separate LUN is required. The LUN for the
CSV must be presented to all nodes in the Hyper-V 3.0 cluster.
RAID 5 (or similar) is suitable for the Cluster Shared Volumes holding the Virtual Hard Disks that in
turn hold SAP Application Servers.
The single CSV running on one LUN can support 10-25 Virtual Machines (likely many more).
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MS Private Cloud Physical Layer
Windows 2012 Hyper-V 3.0 Cluster
VM Layer
Small VM = 4vCPU, 32GB vRAM
In this example this VM is only running 2
SAP ABAP instances – 00 and 01 for an
Large sized ECC 6.6 system
sapapp1_ECC_C_DISK.VHDX
PHYS_MEMSIZE = 16000
All profile parameters kept in DEFAULT.PFL
VHDX: 1 x VHDX for a single large C: Drive
CSV: 1 x CSV shared by all SAP systems
LUN: 1 with CSV Cache
NTFS File System Layer
LOCAL C:\ -> 120GB GPT disk
C:\usr\SAP\ECC\D00 -> ECC instance 00
C:\usr\SAP\ECC\D01 -> ECC instance 01
C:\usr\SAP\<SID>\<Instance Number> -> additional instances
C:\pagefile.sys -> pagefile set to the same size as vRAM = 32GB
C:\Windows -> 32GB minimum disk space
Virtual Hard Disk -> CSV Layer
C:\ClusterStorage\
Volume6
{
SAN Layer
LUN 6
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4 Example Configuration – SAP ASCS SPOF VM
SAP on Microsoft Private Cloud reference deployment can be decomposed into several simple
layers thereby allowing customers and partners to correctly configure Microsoft Private Cloud
infrastructures.
The Single Points of Failure (SPOF) on a SAP system run on the ASCS. SAP ASCS Server Virtual
Machines require some specific configuration to deliver a very Highly Available solution. The
following sections should be reviewed in conjuction with the diagram on the following page. This
section depicts four ASCS running on a two node cluster in Active/Active configuration.
4.1.1 Physical Server
See the Sizing Chapter for information on the physical server configuration. The ASCS cluster nodes
must all be “Small” configuration VMs.
It is not permitted to run any other software or SAP application servers in conjunction with the ASCS.
The reason for this restriction is to expedite troubleshooting of any cluster or failover issues.
Note: all nodes of a ASCS cluster must be “Small” size. See the Sizing Chapter for details.
It is not permitted to install any other software such as SQL Server or additional SAP application
servers onto an ASCS cluster on this reference architecture. The reason for this is to simplify
configuration and troubleshooting
4.1.2 Virtual Machine
Windows Server 2012 Standard Edition or greater should be used for running an SAP ASCS Cluster.
Windows Server 2012 Standard Edition and Datacenter Edition support the same number of cluster
nodes.
See the Sizing Chapter for information on the Virtual Machine sizing.
4.1.2.1
Roles & Features Required for SAP Application Server
Windows Clustering Feature is required to install the ASCS.
The SAP ASCS Cluster Server requires the File Services Role in order to share \SAPLOC & \SAPMNT.
No other Roles or Features are typically required
4.1.2.2
Virtual Machine Affinity
SAP ASCS cluster nodes (the VMs that form the ASCS 2 node cluster) must not run on the same
physical host. This is documented in SAP Note 1374671. See the High Availability Chapter for more
information
4.1.2.3
Windows Server 2012 Server Core
It is not supported at this time to run the SAP application server on Windows Server Core or Hybrid.
The only supported “Shell” is Full GUI. SAP may release the ASCS server on Windows Core in the
future.
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See the Security Chapter for more information on hardening the Guest Virtual Machines
4.1.3 SAP ASCS Cluster Disk Configuration
The SAP ASCS Cluster does not cause significant IO. Typically the IO activity on the \usr\sap file
system is limited to writing trace files and other activity. The vast majority of the IO on a SAP system
is caused by the Database.
In order to simplify the configuration one large C: Drive should be used to hold the following
components:
1. Windows Server 2012 Guest Operating System
2. Pagefile.sys
3. Enqueue Replication -> Instance Number 11, 12, 13, 14
4. SAP Host Agent
Typically 120GB Virtual Hard Disk partitioned into one single large C: Drive is sufficient for this
purpose. It is highly unlikely that the disk would ever fill up on a SAP application server as no files
are stored on SAP Application Servers.
The cluster components must reside on a cluster shared disk – Drive letters P:, Q:, R: and S: are
reserved for holding the following components:
1. P:\usr\sap\<SID>\ASCS -> ASCS System Number 00
2. Q:\usr\sap\<SID>\ASCS -> ASCS System Number 01
3. R:\usr\sap\<SID>\ASCS -> ASCS System Number 02
4. S:\usr\sap\<SID>\ASCS -> ASCS System Number 03
Typically 30GB 4 Virtual Hard Disk partitioned into one single large P: Drive is sufficient for this
purpose. Some SAP components may require more. Always check the SAP Installation Guide
4
SAP Installation Guides mention about 5GB as the minimum requirement.
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VM Host
Name
sapascs1
sapascs2
Home Node
(1 – 5)
1
2
SAP Path on VM
C:\Windows
C:\Pagefile.sys
C:\Program
Files\SAP\HostCtrl\exe
C:\usr\SAP\ECC\ERS
P:\usr\SAP\ECC\ASCS
C:\usr\SAP\BWP\ERS
Q:\usr\SAP\BWP\ASCS
C:\usr\SAP\XIP\ERS
C:\usr\SAP\SLM\ERS
C:\Windows
C:\Pagefile.sys
C:\Program
Files\SAP\HostCtrl\exe
C:\usr\SAP\XIP\ERS
R:\usr\SAP\XIP\ASCS
C:\usr\SAP\SLM\ERS
S:\usr\SAP\SLM\ASCS
C:\usr\SAP\ECC\ERS
C:\usr\SAP\BWP\ERS
Virtual Hard Disk Name host
or SHARED
sapascs1_ECC_C_DISK.VHDX
sapascs1_ECC_C_DISK.VHDX
sapascs1_ECC_C_DISK.VHDX
Cluster Shared Volume VHDX Path on Host
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
SAN
LUN
6
6
6
CSV
Cache
Yes
Yes
Yes
sapascs1_ECC_C_DISK.VHDX
SHARED vHBA or iSCSI disk
sapascs1_ECC_C_DISK.VHDX
SHARED vHBA or iSCSI disk
sapascs1_ECC_C_DISK.VHDX
sapascs1_ECC_C_DISK.VHDX
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
directly presented to VMs (Node A and Node B)
C:\ClusterStorage\Volume6\BWP\<vm name>\Virtual Hard Disks\
directly presented to VMs (Node A and Node B)
C:\ClusterStorage\Volume6\XIP\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\SLM\<vm name>\Virtual Hard Disks\
6
7
6
8
6
6
Yes
No
Yes
No
Yes
Yes
sapascs2_ECC_C_DISK.VHDX
sapascs2_ECC_C_DISK.VHDX
sapascs2_ECC_C_DISK.VHDX
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
6
6
6
Yes
Yes
Yes
sapascs2_ECC_C_DISK.VHDX
SHARED vHBA or iSCSI disk
sapascs2_ECC_C_DISK.VHDX
SHARED vHBA or iSCSI disk
sapascs2_ECC_C_DISK.VHDX
sapascs2_ECC_C_DISK.VHDX
C:\ClusterStorage\Volume6\XIP\<vm name>\Virtual Hard Disks\
directly presented to VMs (Node A and Node B)
C:\ClusterStorage\Volume6\SLM\<vm name>\Virtual Hard Disks\
directly presented to VMs (Node A and Node B)
C:\ClusterStorage\Volume6\ECC\<vm name>\Virtual Hard Disks\
C:\ClusterStorage\Volume6\BWP\<vm name>\Virtual Hard Disks\
6
9
6
10
6
6
Yes
No
Yes
No
Yes
Yes
Table shows a Multi-SID SAP ACS Cluster running on two VMs (in a guest cluster) on a 5 node Microsoft Private Cloud Infrastructure.
ECC 6.5 system SID = ECC, a BW system SID = BWP, a XI system SID = XIP and a Solution Manager system SID = SLM.
There is a standard Windows Cluster configured between sapascs1 and sapascs2 with Node and File Share Witness Majority.
Each SAP ASCS instance is clustered. The ASCS for ECC and BWP run on sapascs1 typically. The ASCS for XIP and SLM run on sapascs2
typically. Enqueue Replication is configured to preserve the lock table if there is a failover. Each SAP system must have its own Shared Disk –
P:, Q: R: and S: are Cluster Shared disks for the cluster between the two VMs.
The Virtual Hard Disks for the SAP application servers boot disk (<host>_<SID>_C_DISK.VHDX) can all reside on the same dedicated Cluster
Shared Volume (using its own dedicated SAN LUN).
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4.1.4 Cluster Shared Volume & Virtual Hard Disk
Windows Server 2012 Cluster Shared Volumes can support many VHDXs and many VHDXs from different
VMs. 10-25 Virtual Machines can share the same set of CSV without performance impact when configured
correctly.
4.1.5 SAN Configuration
A single Cluster Shared Volume on a dedicated single separate LUN is required. The LUN for the CSV must
be presented to all nodes in the Hyper-V 3.0 cluster.
RAID 5 (or similar) is suitable for the Cluster Shared Volumes holding the Virtual Hard Disks that in turn
hold SAP Application Servers.
The single CSV running on one LUN can support 10-25 Virtual Machines (likely many more).
4.1.6 Shared Disk for SAP ASCS
The following two sections provide information about creating a shared disk for the SAP (A)SCS cluster
between two VMs. The VM is to a large extent “unaware” of the fact that it is running on a Hypervisor and
sees the VHDX on the Cluster Shared Volume as just a direct attached SCSI disk. Shared is is required for SAP
and SQL Server cluster5 scenario. These shared cluster disks must be presented directly to the VMs and not
to the physical Hyper-V hosts themselves.
Shared disks should not be used for Quorum detection. The only supported Quorum mode for Microsoft
Private Cloud for SAP systems is “Node and File Share Witness” with Dynamic Quorum.
There are two technologies available for presenting cluster shared disks to a VM – iSCSI and vHBA (Virtual
Fibre Channel)
4.1.6.1
iSCSI
Many storage systems support iSCSI and can present a LUN to a Windows Server 2012 VM via the iSCSI
initiator. It is important that the shared disk presented to both VMs that form the ASCS cluster
4.1.6.2
Virtual Fibre Channel (vHBA)
Windows Server 2012 Hyper-V has a new feature to allow Fibre Channel devices to be presented to a “Virtual”
HBA within a VM and also to preserve connectivity during a LiveMigration.
The steps to setup a Virtual Fibre Channel Shared Cluster Disk are as follows:
1. Confirm that the SAN storage and physical HBA model in the Hyper-V hosts supports NPIV
2. Open Hyper-V manager on each of the physical hosts and click on Virtual SAN Manager…
3. Press Create button, name the Virtual Fibre Channel SAN and Tick at least 2 active ports (WWNN)
SQL Server AlwayOn is generally recommended. SQL Server clustering is for reverse compatibility
only. SQL Server AlwaysOn does not require any shared disks and is preferred for this reference
implementation
5
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4. Repeat this step on all Hyper-V hosts and ensure the naming and configuration is identical to avoid
problems during LiveMigrations
5. Shutdown the VMs that are used for the ASCS cluster (if the VMs are active shutdown one at a time)
6. Open Failover Cluster Manager6 and select Add Hardware -> Fibre Channel Adapter -> Add
7. Select the Virtual SAN created in step 3
8. Take a screenshot and/or copy the WWNN and WWPN and pass this information to the SAN
administrator
9. Request SAN administrator to present LUNs to the VM hosts (both Node A and Node B)
10. Start VM and open Device Manager –> Storage Controllers and check Hyper-V Fibre Channel HBA is
added and working correctly
11. Open Computer Management -> Disk Management: check the disk is present and format the disk
NTFS if required
12. Perform functionality testing:
a. Run Failover Cluster Manager on the Hyper-V host and perform a LiveMigration. Expected
outcome is no interruption of service and no error messages
b. Run Failover Cluster Manager on one of the VMs and perform a Failover. Expected outcome
is no interruption of service and no error messages
Highly available Virtual Machines must be managed with Failover Cluster Manager and not Hyper-V
Manager
6
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MS Private Cloud Physical Layer
Windows 2012 Hyper-V 3.0 Cluster
Cluster
Node 1 =
(A)SCS +
ERS
ACTIVE
Cluster
Node 2 =
ERS
Small VM = 4vCPU, 32GB vRAM
In this example there is a 2 node Active/Passive (A)SCS cluster for an Large sized ECC 6.6
system.
Node 1 is running ASCS + ERS. Node 2 is running ERS. There is a single shared disk P: Drive.
Each 2 node cluster can run many (A)SCS for ECC, BW, EP, PI etc (Multi-SID cluster)
VM Layer
ERS
vHostname for ASCS
vIP for ASCS
ASCS installed on cluster disk
ERS installed on local C: disk
VHDX: 2 x VHDX for a local C: Drive and cluster shared P: Drive for ASCS
CSV: 1 x CSV shared by all SAP systems
LUN: Large – hold all ASCS and all boot disks
CSV for boot disks and ASCS has CSV caching enabled
vHBA or iSCSI Shared Disk
sapascs1_ECC_C_DISK.VHDX
sapascs2_ECC_C_DISK.VHDX
NTFS File System Layer
LOCAL C:\ -> 120GB
disk
C:\usr\SAP\ECC\ERS
Instance 11
C:\pagefile.sys ->
C:\Windows -> 32GB
GPT
– ERS
= 32GB
space
SHARED DISK P:\ -> 30GB
GPT disk
P:\usr\SAP\ECC\ASCS – ECC
Instance 00
\\vhostname\SAPMNT
LOCAL C:\ -> 120GB
disk
C:\usr\SAP\ECC\ERS
Instance 11
C:\pagefile.sys ->
C:\Windows -> 32GB
GPT
– ERS
= 32GB
space
sapascs1_ECC_C_DISK.VHDX
Virtual Hard Disk -> CSV Layer
vHBA or iSCSI Disk Presented Directly to VMs
sapascs2_ECC_P_DISK.VHDX
C:\ClusterStorage\
Volume6
{
LUN 6
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5 Cluster Shared Volumes
Windows 2008 R2 introduced a Cluster Shared Volume restricted to support Hyper-V 2.0
LiveMigration only. Windows Server 2012 Cluster Shared Volumes are a full Cluster Shared File
System that can be used for any application including Hyper-V 3.0.
Cluster Shared Volumes are disks that can be read and written to by all nodes in a Windows cluster.
The disk appears as a special directory under the C: drive (or whichever disk is booted from).
Each cluster shared volume is named “C:\ClusterStorage\Volume” followed by the disk number.
The procedure for converting a disk from a standard cluster shared disk to a CSV is documented
online7.
SQL Server cannot directly run on Cluster Shared Volumes, but SQL Server can run inside a VM
which is running on Cluster Shared Volumes.
5.1 How Many Virtual Machines per CSV?
Unlike VMware VMFS there is no technical reason to limit the number of VMs per CSV volume.
Due to enhancements in the way metadata updates and locking are handled in Windows Server
2012 Cluster Shared Volumes adding many VMs to a single CSV will not cause performance
lantencies.
On very large Hyper-V 3.0 clusters (more than 20 nodes) it may be possible that the physical
servers collectively generate so much IO that the single LUN that comprises a single CSV is
eventually overloaded inside the SAN. Older generation SAN may have issues with this more so
than modern SAN.
It is recommended to separate Sandbox, Development, QAS and Production systems onto separate
CSVs. Therefore most SAP on Microsoft Private Cloud deployments should have at least 3 sets of
CSVs if deployed on the same Hyper-V cluster (Note: Large configurations would typically have a
Hyper-V cluster for non-Prod and a separate Hyper-V cluster for Production)
The following configuration should be followed:
1. C:\ClusterStorage\Volume1 to 9 is reservered for Development
2. C:\ClusterStorage\Volume10 to 19 is reservered for QAS
3. C:\ClusterStorage\Volume20 to 30 is reservered for Production
5.2 Renaming CSV Paths
It is technically possible to rename CSVs from the default “C:\ClusterStorage\Volume1” to
““C:\ClusterStorage\VolumeXX”. Right click on any node and say “Rename..”. Windows Server
2012 will automatically rename the directory on all cluster nodes.
7
http://technet.microsoft.com/en-us/library/jj612868.aspx
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5.3 Cluster Shared Volume Cache
Cluster shared volume caching can dramatically improve VM boot times. This feature should only
be used on the CSV holding the boot disk and SAP ASCS disk (LUN 6) and not any other CSV. Do
not enable CSV cache on any CSV holding SQL Server datafiles.
5.3.1 CsvEnableBlockCache
0 = Disabled (default)
1 = Enabled for that LUN
Requires recycling the resource to take effect
This is a private property of the cluster Physical Disk resource. It allows you to enable CSV Cache
on an individual disk. This gives you the flexibility to configure cache for read intensive VMs
running on some disks, while allowing you to disable and prevent random I/O on other disks from
purging the cache. For example parent VHDX’s with high reads you would enable caching on
Disk1, and high writes for differencing disks the CSV cache could be disabled on Disk2. The default
setting is 0 for disabled, setting to a value of 1 enables CSV Block Cache on that disk.
5.3.2 SharedVolumeBlockCacheSizeInMB
0 = Disabled
Non-zero = the amount of RAM in MB to be used for cache on all nodes in the cluster
1024 recommended value
No downtime required to modify
5.3.3 How to Set CSV Cache
To enable CSV cache follow the procedure below
1. Open an elevated Windows PowerShell prompt
2. Define the size of the size of the cache to be reserved
(Get-Cluster). SharedVolumeBlockCacheSizeInMB = 1024
3. Enable CSV Cache on an individual disk
Get-ClusterSharedVolume “<disk name>” | SetClusterParameter CsvEnableBlockCache 1
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6 Virtual Hard Disk Configuration - VHDX
Windows Server 2012 has a new Virtual Hard Disk format called VHDX. The new Virtual Hard Disk
format has a much larger storage capacity8 than Windows 2008 R2 VHDX files. A Virtual Hard Disk
file is a “Disk in a File”. The disk inside the Virtual Hard Disk file can be formatted, partitioned and
handled just as any other physical disk.
6.1 VHDX Types
There are several different Virtual Hard Disk types for Windows Server 2012.
6.1.1 Fixed, Dynamic & Differencing
Only Fixed disks are supported for SAP on Microsoft Private Cloud reference architecture. Do not use
pass through disks.
6.1.2 Windows 2008 VHD vs. Windows Server 2012 VHDX
Windows Server 2012 VHDX disks should be used in all cases. Customers planning Hybrid Windows
Azure and on premise Private Cloud deployments (which is not covered in this documentation)
should note that Windows Azure is not compatible with VHDX. Windows Azure is currently not
supported by SAP for Production systems
6.2 MBR, GPT, NTFS AUS Size and other options
Disks should be formatted for GPT – Guid Partition Table. GPT is more resilant than MBR9. MBR is
limited in size to 2TB.
All Virtual Hard disks (the VHDX file system) that hold SQL Server datafiles or log files must be
formatted with 64k NTFS Allocation Unit size.
The NTFS allocation unit size on the Cluster Shared Volumes themselves should be formatted with
the default NTFS allocation unit size (4k).
To verify the NTFS allocation unit size run the command CHKDSK /i/c
Windows has scanned the file system and found no problems.
No further action is required.
234067967
107766292
14968
0
171883
65536
126114824
KB
KB
KB
KB
KB
KB
KB
total disk space.
in 44845 files.
in 10960 indexes.
in bad sectors.
in use by the system.
occupied by the log file.
available on disk.
4096 bytes in each allocation unit.
8
http://technet.microsoft.com/en-us/library/hh831446.aspx
9
http://msdn.microsoft.com/en-us/windows/hardware/gg463525.aspx
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58516991 total allocation units on disk.
31528706 allocation units available on disk.
C:\>
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7 Appendix 2 – Links Page
Required OSS Notes:
1732161 - SAP Systems on Windows Server 2012
1811298 - SAP NetWeaver Upgrade/Update on Windows Server 2012
1753578 - Windows Server 2012 in Virtual Environments
Blog Articles:
CSV Cache http://blogs.msdn.com/b/clustering/archive/2012/03/22/10286676.aspx
Channel9:
Cluster Shared Volumes Reborn in Windows Server 2012: Deep Dive
http://channel9.msdn.com/Events/TechEd/Europe/2012/WSV430
Failover Clustering and Hyper-V: Multi-Site Disaster Recovery
http://channel9.msdn.com/Events/TechEd/NorthAmerica/2011/VIR303
Whitepapers:
Technet MSDN:
Use Cluster Shared Volumes in a Windows Server 2012 Failover Cluster
http://technet.microsoft.com/en-us/library/jj612868.aspx
CSV Cache
http://technet.microsoft.com/en-us/library/jj612868.aspx
Hyper-V Scalability in Windows Server 2012
http://technet.microsoft.com/en-us/library/jj680093.aspx
Hyper-V: How to get the most from your virtualized disk performance (IDE vs. SCSI vDisks)
http://blogs.msdn.com/b/tvoellm/archive/2007/12/12/which-is-better-ide-or-scsi-windows-servervirtualization-08-code-name-viridian-controller-performance.aspx
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