Tag Archive for Microsoft

Process Explorer (Microsoft Product)

July 23, 2012 microsoft, Process Explorer No comments

Introduction

Ever wondered which program has a particular file or directory open? Now you can find out. Process Explorer shows you information about which handles and DLLs processes have opened or loaded.

The Process Explorer display consists of two sub-windows. The top window always shows a list of the currently active processes, including the names of their owning accounts, whereas the information displayed in the bottom window depends on the mode that Process Explorer is in: if it is in handle mode you’ll see the handles that the process selected in the top window has opened; if Process Explorer is in DLL mode you’ll see the DLLs and memory-mapped files that the process has loaded. Process Explorer also has a powerful search capability that will quickly show you which processes have particular handles opened or DLLs loaded.

The unique capabilities of Process Explorer make it useful for tracking down DLL-version problems or handle leaks, and provide insight into the way Windows and applications work.

Link for Download

http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx

Terminal Services Profiles and Home Folders

July 3, 2012 microsoft, Terminal Services No comments

Many Administrators misunderstand the use of the Terminal Services Home Folder. The setting which can be configured as part of the user account or through Group Policy determines the location of a folder that is used by Terminal Services to store user specific files for multi user applications.

Logging in Using the Terminal Services Client Software

(Remote Desktop Services User Profile)

Specifies the profile path assigned to the user when the user connects to an RD Session Host server.
Assigns the user a separate profile for Remote Desktop Services sessions. Many of the common options that are stored in profiles, such as screen savers and animated menu affects, are not desirable when using Remote Desktop Services

  • If a Terminal Services Profile is specified, this path is used.
  • If this path is not specified, but a User Profile is specified, this path is used.
  • If neither path is specified, an existing local profile is used, or one is created in the %SYSTEMDRIVE%\Documents and Settings\%username% folder.
  • If both a Terminal Services Profile and a User Profile are specified, the Terminal Services Profile is used.

(Remote Desktop Services Home Folder)

  • If a Terminal Services Home Directory is specified, this path is used.
  • If this path is not specified, but a Home Folder is specified, this path is used.
  • If neither path is specified, the Home Directory is set to the %SYSTEMDRIVE%\Documents and Settings\%username% folder.
  • If both a Terminal Services Home Directory and User Home Folder are specified, the Terminal Services Home Directory is used.

VMware vSphere support for Microsoft clustering solutions on VMware

July 2, 2012 Clustering, Clustering, VMware No comments

Links

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1037959

https://www.vmware.com/pdf/vsphere4/r41/vsp_41_mscs.pdf

What is the difference between Program files (x86) and Program files folders on Windows Servers?

June 22, 2012 microsoft No comments

Program files (x86) provides you with the location for 32bit software, and the Program files folder is the one for your 64bit software. Because Windows Vista can run 32bit applications using the wow64 emulator, it is a good design decision to separate the location of programs with different architecture types.

If you are just simply installing programs, either from their media or from a download, then you don’t need to worry about which directory they will get installed to as this is taken care of for you.

Generally speaking, unless a program specifically mentions 64-bit then it will be installed in the (x86) folder. Note that some programs do not install in either folder; instead they create and use their own.

They’re kept separate so you can have both the 32bit and 64bit version of the same software installed at the same time. It’s also there for compatibility, as some 32bit programs depend on certain resources being in the “Common Files” folder that wouldn’t usually be available (or overwritten by a 64bit version) on a 64bit system.

Microsoft themselves uses it this way for some of their own applications. You have two copies of Windows Media Player, one 32bit (in Program Files (x86) and the other 64bit (in Program Files).

Key Windows Performance Counters, Info and Limits

June 21, 2012 microsoft, Performance No comments

Key Windows Performance Counters, Info and Limits

Counter

Description

What to watch for
Logical Disk\% Free Space Measures the percentage of free space of the selected Logical Disk If it is below 15% then you run the risk of running out of space to store critical O/S files
PhysicalDisk\Idle Time Measures the percentage of time the disk was idle during the sample interval If this value falls below 20% the disk system is said to be saturated and you should install a faster disk system
PhysicalDisk\Avg. Disk Sec/Read Measures the average time in seconds to read data from the disk If this value is larger than 25 milliseconds the disk system is experiencing latencyFor SQL and Exchange the threshold is lower – 10ms
PhysicalDisk\Avg. Disk Sec/Write Measures the average time in seconds to write data from the disk If this value is larger than 25 milliseconds the disk system is experiencing latencyFor SQL and Exchange the threshold is lower – 10ms
Physical Disk\Avg Queue Length How many I/O Operations are waiting for the Hard Drive to become available If the value of the counter is larger than twice the number of disk spindles in an array then the disk may be a bottleneck
Memory\Cache Bytes Indicates the amount of memory being used for the file system cache. There will be a bottleneck if the value is greater than 300MB
Processor\%Idle Time % Idle Time is the percentage of time the processor is idle during the sample interval Below 20% and you are running at CPU saturation if this prolonged
Processor\Interrupts/sec The numbers of interrupts the processor was asked to respond to. Interrupts are generated from hardware components like hard disk controller adapters and network interface cards. A sustained value over 1000 is usually an indication of a problem. Problems would include a poorly configured drivers, errors in drivers, excessive utilization of a device (like a NIC on an IIS server), or hardware failure
Processor\%Processor Time Measures  how much time the processor actually spends working on productive threads and how often it was busy servicing requests. It actually provides a measurement of how often the system is doing nothing subtracted from 100%. This is a simpler calculation for the processor to make. The processor can never be sitting idle waiting to the next task, unlike our cashier. The CPU must always have something to do. It’s like when you turn on the computer, the CPU is a piece of wire that electric current is always running through, thus it must always be doing something. NT give the CPU something to do when there is nothing else waiting in the queue. This is called the idle thread. The system can easily measure how often the idle thread is running as opposed to having to tally the run time of each of the other process threads. Then , the counter simply subtracts the percentage from 100%. This counter is a natural choice that will give use the amount of time that this particular process spends using the processor resource.
Memory\Page Faults/sec This counter gives a general idea of how many times information being requested is not where the application (and VMM) expects it to be. The information must either be retrieved from another location in memory or from the pagefile. While a sustained value may indicate trouble here, you should be more concerned with hard page faults that represent actual reads or writes to the disk. Remember that the disk access is much slower than RAM
Memory\%Committed Bytes in use This counter indicates the total amount of memory that has been committed for the exclusive use of any of the services or processes on Windows NT. Should this value approach the committed limit, you will be facing a memory shortage of unknown cause, but of certain severe consequence.
Memory\Available Bytes This counter indicates the amount of memory that is left after nonpaged pool allocations, paged pool allocations, process’ working sets, and the file system cache have all taken their piece.
System\System Calls/sec This counter is a measure of the number of calls made to the system components, Kernel mode services. This is a measure of how busy the system is taking care of applications and services—software stuff. When compared to the Interrupts/Sec it will give you an indication of whether processor issues are hardware or software related. See Processor : Interrupts/Sec for more information
System\Threads Threads is the number of threads in the computer at the time of data collection. This is an instantaneous count, not an average over the time interval.  A thread is the basic executable entity that can execute instructions in a processor. Monitor loosely
System\Processor Queue Length Gives an indication of how many threads are waiting for execution. If this counter is consistently higher than around 5 when processor utilization approaches 100%, then this is a good indication that there is more work (active threads) available (ready for execution) than the machine’s processors are able to handle. Note that this is not always a hard and fast indicator however, for some services like IIS 6 pool and manage their own worker threads, so on a busy web server for example you would want to look at other counters like ASP\Requests Queued or ASP.NET\Requests Queued as well. Furthermore, the larger the number of active services and applications running on your server, the busier the processor queue will normally be, so on a multi-role server running near 100% utilization content may only be a significant factor once System\Processor Queue Length exceeds something like 10 instead of 5 as mentioned previously.
Network Interface : Bytes Sent/sec This is how many bytes of data are sent to the NIC. This is a raw measure of throughput for the network interface. We are really measuring the information sent to the interface which is the lowest point we can measure. If you have multiple NIC, you will see multiple instances of this particular counter. Dependent on NIC Speed
Network Interface: Bytes Received/sec. This, of course, is how many bytes you get from the NIC. This is a measure of the inbound traffic In measuring the bytes, NT isn’t too particular at this level. So, no matter what the byte is, it is counted. This will include the framing bytes as opposed to just the data Dependent on NIC Speed

 

Reliability Monitor in Windows 2008

June 19, 2012 microsoft, Performance No comments

Reliability Monitor is an advanced tool which measures hardware and software problems and changes to the computer. It provides a stability index which ranges from 1 (Least Stable) to 10 (Most Stable)

Accessing Reliability Monitor

You can access it 2 ways.Either by typing in perfmon/rel or following the steps below

  • Open Action Center
  • Click Maintenance
  • Then under Check for Solutions to Problem Reports, click View Reliability History

What can you do?

  • Click on any event on the graph to view details
  • Click Days or Weeks to view the stability index
  • Click items in the Action Pane to view more info about it
  • Click View All Problem Reports to view only the problems that have occurred on your computer

Gathering System Stability Data

The Reliability Monitor displays data gathered by the Reliability Analysis Component (RAC) This is implemented using RACAgent.exe which is scheduled to run once an hour. Reliability Monitor starts displaying a system stability index rating and specific event information 24 hours after system installation, and the RACAgent task runs by default after that O/S is installed. If it has been disabled, it must be manually enabled from the Task Scheduler snap-in for the MMC.

Enable RACAgent

To enable to RACAgent Task, you must use an account which is a member of the Local Administrators Group on the computer.

  • Click Start > Search > Type taskschd.msc
  • Expand Task Scheduler Library
  • Expand Microsoft
  • Expand Windows
  • Select RAC
  • Right click RAC and select View and Show Hidden Tasks
  • In the Results Pane, right click RACAgent and select Enable

Performance and Resource Monitoring in Windows Server 2008

June 19, 2012 microsoft, Performance No comments

What does Windows Reliability and Performance Monitor do?

Windows Reliability and Performance Monitor is a Microsoft Management Console (MMC) snap-in that combines the functionality of previous stand-alone tools including Performance Logs and Alerts, Server Performance Advisor, and System Monitor. It provides a graphical interface for customizing performance data collection and Event Trace Sessions.

It also includes Reliability Monitor, an MMC snap-in that tracks changes to the system and compares them to changes in system stability, providing a graphical view of their relationship

What new functionality does this feature provide?

Features of Windows Reliability and Performance Monitor new to Windows Server 2008 include the following.

Data Collector Sets

An important new feature in Windows Reliability and Performance Monitor is the Data Collector Set, which groups data collectors into reusable elements for use with different performance monitoring scenarios. Once a group of data collectors are stored as a Data Collector Set, operations such as scheduling can be applied to the entire set through a single property change.

Windows Reliability and Performance Monitor also includes default Data Collector Set templates to help system administrators begin collecting performance data specific to a Server Role or monitoring scenario immediately.

Wizards and templates for creating logs

Adding counters to log files and scheduling their start, stop, and duration can now be performed through a Wizard interface. In addition, saving this configuration as a template allows system administrators to collect the same log on subsequent computers without repeating the data collector selection and scheduling processes. Performance Logs and Alerts features have been incorporated into the Windows Reliability and Performance Monitor for use with any Data Collector Set.

Resource View

The home page of Windows Reliability and Performance Monitor is the new Resource View screen, which provides a real-time graphical overview of CPU, disk, network, and memory usage. By expanding each of these monitored elements, system administrators can identify which processes are using which resources. In previous versions of Windows, this real-time process-specific data was only available in limited form in Task Manager.

Reliability Monitor

Reliability Monitor calculates a System Stability Index that reflects whether unexpected problems reduced the reliability of the system. A graph of the Stability Index over time quickly identifies dates when problems began to occur. The accompanying System Stability Report provides details to help troubleshoot the root cause of reduced reliability. By viewing changes to the system (installation or removal of applications, updates to the operating system, or addition or modification of drivers) side by side with failures (application failures, operating system crashes, or hardware failures), a strategy for addressing the issues can be developed quickly.

Unified property configuration for all data collection, including scheduling

Whether creating a Data Collector Set for one time use or to log activity on an ongoing basis, the interface for creation, scheduling, and modification is the same. If a Data Collector Set proves to be useful for future performance monitoring, it does not need to be re-created. It can be reconfigured or copied as a template.

User-friendly diagnosis reports

Users of Server Performance Advisor in Windows Server 2003 can now find the same kinds of diagnosis reports in Windows Reliability and Performance Monitor in Windows Server 2008. Report generation time is improved and reports can be created from data collected by using any Data Collector Set. This allows system administrators to repeat reports and assess how changes have affected performance or the report’s recommendations.

Accessing Performance Monitor

Membership in the local Performance Log Users group, or equivalent, is the minimum required to complete this procedure.

To start Performance Monitor

  • Click Start, click in the Start Search box, type perfmon, and press ENTER.
  • In the navigation tree, expand Monitoring Tools, and then click Performance Monitor.

You can also use Performance Monitor to view real-time performance data on a remote computer.

Membership in the target computer’s Performance Log Users group, or equivalent, is the minimum required to complete this procedure

To view performance counters from a remote computer, the Performance Logs and Alerts firewall exception must be enabled on the remote computer. In addition, members of the Performance Log Users group must also be members of the Event Log Readers group on the remote computer

Creating Data Collection Sets

A Data Collector Set is the building block of performance monitoring and reporting in Windows Performance Monitor. It organizes multiple data collection points into a single component that can be used to review or log performance. A Data Collector Set can be created and then recorded individually, grouped with other Data Collector Set and incorporated into logs, viewed in Performance Monitor, configured to generate alerts when thresholds are reached, or used by other non-Microsoft applications. It can be associated with rules of scheduling for data collection at specific times. Windows Management Interface (WMI) tasks can be configured to run upon the completion of Data Collector Set collection.

Data Collector Sets can contain the following types of data collectors:

  • Performance counters
  • Event trace data
  • System configuration information (registry key values)

Real Time Example

  • Start Performance Monitor
  • Right-click anywhere in the Performance Monitor display pane, point to New, and click Data Collector Set. The Create New Data Collector Set Wizard starts. The Data Collector Set created will contain all of the data collectors selected in the current Performance Monitor view.

  • Type in a name for your Data Collection Set and Choose from Template

  • Choose a Template (System Performance for this example)

  • Choose where the Data is going to be saved

  • Choose who to run this as. If you have permissions then this can be left as default. Choose to open the properties for this job

  • The General Tab

  • Click Directory

  • Click Security

  • Click Schedule

  • Stop Condition

  • Click Task

Reports

When this job has finished, Performance Monitor will reconcile a report to show the full history of this job.

Analysing the Results

Data Analysis
A tool that Microsoft support relies on to analyze Performance Monitor logs is the Performance Analysis of Logs (PAL) Tool. Clint Huffman, a Microsoft senior premier field engineer, wrote the 6,000-line VBScript tool, which is free and open source. PAL lets administrators easily analyze Performance Monitor logs without requiring them to be experts in performance counters or Windows architecture.

PAL contains a wizard-based UI that asks specific information about the system, which PAL passes as arguments to the VBScript program. PAL picks up where other log analyzers leave off, such as taking into account whether the system is 64-bit or 32-bit, whether the /3GB switch is used, and how much physical memory is installed—all variables that affect system performance. PAL uses these variables along with known thresholds, which were determined by engineers with years of experience, to determine the analysis that’s displayed. PAL provides a chronological order of alerts, so that you can correlate your system’s performance to any problems that you noticed at specific times.

Counters and Limits

http://technet.microsoft.com/en-us/library/cc768048.aspx

Planning a Terminal Services Deployment

June 16, 2012 microsoft, Terminal Services No comments

The first step in planning a deployment is understanding how the following Terminal Sever components fit together

  • Terminal Server

The server itself is at the core component of a Terminal Services deployment. This is the server that the clients connect to so they can access their applications

  • Terminal Server Farm

A Terminal Server farm is a collection of Terminal Servers used to provide high availability and load balancing to clients on an organisational network. Client connections to Terminal Server Farms are mediated by Terminal Services Session Directory Servers. Terminal Server farms are more likely to be deployed at large sites than small ones

  • License Servers

License servers provide Terminal Server Client Access Licenses (TS CALS) to Terminal Servers on the network. Unless a license server is deployed, clients are only able to connect to Terminal Services for a limited time only.

  • Terminal Services Gateway Servers (TS Gateway)

These servers provide access to Terminal Servers to clients on untrusted networks. In Enterprise networks, you can use a TS Gateway server as a bridge between the standard internal network and a Terminal Server farm on a network protected by server isolation policies

Terminal Server Licensing

All clients that connect to a Terminal Server require a TS CAL. This license is not included with the O/S a client uses or a standard server license.

TS CALs are managed by a Terminal Server Licensing server

  • What is the scope of the licensing server. Will it service clients in the domain or workgroup or manage the licenses for all clients in the forest
  • How will the license server be activated with Microsoft. Automatic, Web Browser or Telephone
  • How many license servers do you need for your organisation?
  • What type of licenses will be deployed

Terminal Server Session Broker

The Terminal Server Session Broker service simplifies the process of adding more capacity to an existing Terminal Services Deployment. It enables Load Balancing of terminal services in a group and ensures the reconnection of clients to existing sessions in that group. In Terminal Server Session Broker, a group of Terminal Servers is called a Farm.

The Terminal Server Session Broker is a database which keeps track of TS sessions. TS can work with DNS Round Robin or with NLB. When configured with NLB, the Terminal Server Session Broker Service monitors all servers in the group and allocates clients to to the servers which have the most amount of free resource.

When used with DNS Round Robin, clients are still distributed, the main benefit being is that Terminal Server Session Broker remembers where a client is connected. TS Load Balancing is restricted to Windows 2008 Terminal Servers only

Clients must support RDP 5.2 or later

Each Terminal Server must have the same application configuration

The following diagram provides a more detailed representation of the traffic flow. In the diagrammed scenario, all terminal servers in the farm have host resource records in DNS that map to the terminal server farm name (“Farm1”). Therefore, any terminal server in the farm can act as a redirector and process the initial connection requests

http://technet.microsoft.com/en-us/library/cc772418(v=ws.10).aspx

Terminal Server Gateway Server

Plan the deployment of Terminal Server Gateway Servers when you need to enable RDP over HTTPS connections to RDP Servers located on Protected internal networks to clients on the internet or untrusted networks. TS Gateway servers are not limited to screened subnets between internal networks and the internet but can also be deployed to enable access to servers that are the subject of IPsec isolation policies

Failover Clusters in Windows Server 2008 – Quorums

June 7, 2012 Clustering, microsoft No comments

What is a cluster?

A failover cluster is a group of independent computers that work together to increase the availability of applications and services. The clustered servers (called nodes) are connected by physical cables and by software. If one of the cluster nodes fails, another node begins to provide service (a process known as failover). Users experience a minimum of disruptions in service.

Are there any special considerations?

Microsoft supports a failover cluster solution only if all the hardware components are marked as “Certified for Windows Server 2008 R2.” In addition, the complete configuration (servers, network, and storage) must pass all tests in the Validate a Configuration wizard, which is included in the Failover Cluster Manager snap-in.

Note that this policy differs from the support policy for server clusters in Windows Server 2003, which required the entire cluster solution to be listed in the Windows Server Catalog under Cluster Solutions.

Cluster validation is intended to catch hardware or configuration problems before the cluster goes into production. Cluster validation helps to ensure that the solution you are about to deploy is truly dependable. Cluster validation can also be performed on configured failover clusters as a diagnostic tool.

Step by Step Guide

  • Run the cluster validation wizard for a failover cluster
  • If the cluster does not yet exist, choose the servers that you want to include in the cluster, and make sure you have installed the failover cluster feature on those servers. To install the feature, on a server running Windows Server 2008 or Windows Server 2008 R2, click Start, click Administrative Tools, click Server Manager, and under Features Summary, click Add Features. Use the Add Features wizard to add the Failover Clustering feature.
  • If the cluster already exists, make sure that you know the name of the cluster or a node in the cluster
  • For a planned cluster with all hardware connected: Run all tests.
  • For a planned cluster with parts of the hardware connected: Run System Configuration tests, Inventory tests, and tests that apply to the hardware that is connected (that is, Network tests if the network is connected or Storage tests if the storage is connected).
  • For a cluster to which you plan to add a server: Run all tests. Before you run them, be sure to connect the networks and storage for all servers that you plan to have in the cluster.
  • For troubleshooting an existing cluster: If you are troubleshooting an existing cluster, you might run all tests, although you could run only the tests that relate to the apparent issue.
  • In the failover cluster snap-in, in the console tree, make sure Failover Cluster Management is selected and then, under Management, click Validate a Configuration.

  • Follow the instructions in the wizard to specify the servers and the tests, and run the tests.
  • Note that when you run the cluster validation wizard on unclustered servers, you must enter the names of all the servers you want to test, not just one.
  • The Summary page appears after the tests run.
  • While still on the Summary page, click View Reportto view the test results.To view the results of the tests after you close the wizard, see SystemRoot\Cluster\Reports\Validation Report date and time.html where SystemRoot is the folder in which the operating system is installed (for example, C:\Windows)

Error Chart

Configuring the Quorum in a Failover Cluster

In simple terms, the quorum for a cluster is the number of elements that must be online for that cluster to continue running. In effect, each element can cast one “vote” to determine whether the cluster continues running. The voting elements are nodes or, in some cases, a disk witness or file share witness. Each voting element (with the exception of a file share witness) contains a copy of the cluster configuration, and the Cluster service works to keep all copies synchronized at all times

Note that the full function of a cluster depends not just on quorum, but on the capacity of each node to support the services and applications that fail over to that node. For example, a cluster that has five nodes could still have quorum after two nodes fail, but each remaining cluster node would continue serving clients only if it had enough capacity to support the services and applications that failed over to it.

Why Quorum is necessary

When network problems occur, they can interfere with communication between cluster nodes. A small set of nodes might be able to communicate together across a functioning part of a network, but might not be able to communicate with a different set of nodes in another part of the network. This can cause serious issues. In this “split” situation, at least one of the sets of nodes must stop running as a cluster.

To prevent the issues that are caused by a split in the cluster, the cluster software requires that any set of nodes running as a cluster must use a voting algorithm to determine whether, at a given time, that set has quorum. Because a given cluster has a specific set of nodes and a specific quorum configuration, the cluster will know how many “votes” constitutes a majority (that is, a quorum). If the number drops below the majority, the cluster stops running. Nodes will still listen for the presence of other nodes, in case another node appears again on the network, but the nodes will not begin to function as a cluster until the quorum exists again.

For example, in a five node cluster that is using a node majority, consider what happens if nodes 1, 2, and 3 can communicate with each other but not with nodes 4 and 5. Nodes 1, 2, and 3 constitute a majority, and they continue running as a cluster. Nodes 4 and 5 are a minority and stop running as a cluster, which prevents the problems of a “split” situation. If node 3 loses communication with other nodes, all nodes stop running as a cluster. However, all functioning nodes will continue to listen for communication, so that when the network begins working again, the cluster can form and begin to run.

Overview of the Quorum Nodes

There have been significant improvements to the quorum model in Windows Server 2008. In Windows Server 2003, almost all server clusters used a disk in cluster storage (the “quorum resource”) as the quorum. If a node could communicate with the specified disk, the node could function as a part of a cluster, and otherwise it could not. This made the quorum resource a potential single point of failure. In Windows Server 2008, a majority of ‘votes’ is what determines whether a cluster achieves quorum. Nodes can vote, and where appropriate, either a disk in cluster storage (called a “disk witness”) or a file share (called a “file share witness”) can vote. There is also a quorum mode called No Majority: Disk Only which functions like the disk-based quorum in Windows Server 2003. Aside from that mode, there is no single point of failure with the quorum modes, since what matters is the number of votes, not whether a particular element is available to vote.

This new quorum model is flexible and you can choose the mode best suited to your cluster.

Important: In most situations, it is best to use the quorum mode selected by the cluster software. If you run the quorum configuration wizard, the quorum mode that the wizard lists as “recommended” is the quorum mode chosen by the cluster software. We only recommend changing the quorum configuration if you have determined that the change is appropriate for your cluster.

There are four quorum modes:

  • Node Majority: Each node that is available and in communication can vote. The cluster functions only with a majority of the votes, that is, more than half.
  • Node and Disk Majority: Each node plus a designated disk in the cluster storage (the “disk witness”) can vote, whenever they are available and in communication. The cluster functions only with a majority of the votes, that is, more than half.
  • Node and File Share Majority: Each node plus a designated file share created by the administrator (the “file share witness”) can vote, whenever they are available and in communication. The cluster functions only with a majority of the votes, that is, more than half.
  • No Majority: Disk Only: The cluster has quorum if one node is available and in communication with a specific disk in the cluster storage.

Choosing the Quorum Mode for a particular cluster

Description of Cluster

Quorum Recommendation

Odd number of nodes

Node Majority

Even number of nodes (but not a multi-site cluster)

Node and Disk Majority

Even number of nodes, multi-site cluster

Node and File Share Majority

Even number of nodes, no shared storage

Node and File Share Majority

Node Majority

The following diagram shows Node Majority used (as recommended) for a cluster with an odd number of nodes.In this mode, each node gets one vote. In certain circumstances, you might want to install a hotfix that lets you select which nodes will have votes. This can be useful with certain multi-site clusters, for example, where you want one site to have more votes than other sites in a disaster recovery situation

Node and Disk Majority

The following diagram shows Node and Disk Majority used (as recommended) for a cluster with an even number of nodes. Each node can vote, as can the disk witness.

  • Use a small Logical Unit Number (LUN) that is at least 512 MB in size.
  • Choose a basic disk with a single volume.
  • Make sure that the LUN is dedicated to the disk witness. It must not contain any other user or application data.
  • Choose whether to assign a drive letter to the LUN based on the needs of your cluster. The LUN does not have to have a drive letter (to conserve drive letters for applications).
  • As with other LUNs that are to be used by the cluster, you must add the LUN to the set of disks that the cluster can use. For more information, see http://go.microsoft.com/fwlink/?LinkId=114539.
  • Make sure that the LUN has been verified with the Validate a Configuration Wizard.
  • We recommend that you configure the LUN with hardware RAID for fault tolerance.
  • In most situations, do not back up the disk witness or the data on it. Backing up the disk witness can add to the input/output (I/O) activity on the disk and decrease its performance, which could potentially cause it to fail.
  • We recommend that you avoid all antivirus scanning on the disk witness.
  • Format the LUN with the NTFS file system.

If there is a disk witness configured, but bringing that disk online will not achieve quorum, then it remains offline. If bringing that disk online will achieve quorum, then it is brought online by the cluster software

Node and File Share Majority

The following diagram shows Node and File Share Majority used (as recommended) for a cluster with an even number of nodes and a situation where having a file share witness works better than having a disk witness. Each node can vote, as can the file share witness.

  • Use a Server Message Block (SMB) share on a Windows Server 2003 or Windows Server 2008 file server.
  • Make sure that the file share has a minimum of 5 MB of free space.
  • Make sure that the file share is dedicated to the cluster and is not used in other ways (including storage of user or application data).
  • Do not place the share on a node that is a member of this cluster or will become a member of this cluster in the future.
  • You can place the share on a file server that has multiple file shares servicing different purposes. This may include multiple file share witnesses, each one a dedicated share. You can even place the share on a clustered file server (in a different cluster), which would typically be a clustered file server containing multiple file shares servicing different purposes.
  • For a multi-site cluster, you can co-locate the external file share at one of the sites where a node or nodes are located. However, we recommend that you configure the external share in a separate third site.
  • Place the file share on a server that is a member of a domain, in the same forest as the cluster nodes.
  • For the folder that the file share uses, make sure that the administrator has Full Control share and NTFS permissions.
  • Do not use a file share that is part of a Distributed File System (DFS) Namespace

No Majority – Disk only

The following illustration shows how a cluster that uses the disk as the only determiner of quorum can run even if only one node is available and in communication with the quorum disk. It also shows how the cluster cannot run if the quorum disk is not available (single point of failure). For this cluster, which has an odd number of nodes, Node Majority is the recommended quorum mode.

  • Use a small Logical Unit Number (LUN) that is at least 512 MB in size.
  • Choose a basic disk with a single volume.
  • Make sure that the LUN is dedicated to the disk witness. It must not contain any other user or application data.
  • Choose whether to assign a drive letter to the LUN based on the needs of your cluster. The LUN does not have to have a drive letter (to conserve drive letters for applications).
  • As with other LUNs that are to be used by the cluster, you must add the LUN to the set of disks that the cluster can use. For more information, see http://go.microsoft.com/fwlink/?LinkId=114539.
  • Make sure that the LUN has been verified with the Validate a Configuration Wizard.
  • We recommend that you configure the LUN with hardware RAID for fault tolerance.
  • In most situations, do not back up the disk witness or the data on it. Backing up the disk witness can add to the input/output (I/O) activity on the disk and decrease its performance, which could potentially cause it to fail.
  • We recommend that you avoid all antivirus scanning on the disk witness.
  • Format the LUN with the NTFS file system.

If there is a disk witness configured, but bringing that disk online will not achieve quorum, then it remains offline. If bringing that disk online will achieve quorum, then it is brought online by the cluster software

Viewing the Quorum Configuration

  • To open the failover cluster snap-in, click Start, click Administrative Tools, and then click Failover Cluster Management (in Windows Server 2008) or Failover Cluster Manager (in Windows Server 2008 R2).If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.
  • In the console tree, if the cluster that you want to view is not displayed, right-click Failover Cluster Management or Failover Cluster Manager, click Manage a Cluster, and then select the cluster you want to view
  • In the center pane, find Quorum Configuration, and view the description
  • In the following example, the quorum mode is Node and Disk Majority and the disk witness is Cluster Disk 2.

 

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