Download Multipath I/O (MPIO) Storage Driver for Windows*

Опубликовано 26.07.2017 | Автор:

These modules are called device-specific modules DSMs. The concepts around DSMs are discussed later in this document. Keeping mission-critical data continuously available has become a requirement over a wide range of customer segments from small business to datacenter environments. Enterprise environments that use Windows Server require no downtime for key workloads, including file server, database, messaging, and other line of business applications. This level of availability can be difficult and very costly to achieve, and it requires that redundancy be built in at multiple levels: Clustering is the use of multiple servers, host bus adapters HBAs , and storage devices that work together to provide users with high application availability.

If a server experiences a hardware failure or is temporarily unavailable, end users are still able to transparently access data or applications on a redundant cluster node. In addition to providing redundancy at the server level, clustering can also be used as a tool to minimize the downtime required for patch management and hardware maintenance. Clustering solutions require software that enables transparent failover between systems. Although both MPIO and Failover Clustering result in high availability and improved performance, they are not equivalent concepts.

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While Failover Clustering provides high application availability and tolerance of server failure, MPIO provides fault tolerant connectivity to storage. By employing MPIO and Failover Clustering together as complimentary technologies, users are able to mitigate the risk of a system outage at both the hardware and application levels. These redundant hardware paths are made up of components such as cabling, host bus adapters HBAs , switches, storage controllers, and possibly even power.

As more and more data is consolidated on storage area networks SANs , the potential loss of access to storage resources is unacceptable. To mitigate this risk, high availability solutions, such as MPIO, have now become a requirement. We will briefly outline in this section how MPIO works with DSM in discovering and configuring the devices. Without any multipath driver, the same devices through different physical paths would appear as totally different devices, thereby leaving room for data corruption.

Installing and Configuring MPIO

Following is the sequence of steps that the device driver stack walks through in discovering, enumerating, and grouping the physical devices and device paths into a logical set. This assumes a scenario where a new device is presented to the server. If a new path for this same device arrives, MPIO then works with the DSM to determine whether this device is the same as any other claimed device.

It then groups this physical path for the same device into a logical set for the multipath group that is called a pseudo-Logical Unit Number pseudo-LUN. For dynamic discovery to work correctly, some form of identifier must be identified and obtainable regardless of the path from the host to the storage device. Each logical unit must have a unique hardware identifier. The MPIO driver package does not use disk signatures placed in the data area of a disk for identification purposes by software.

Instead, the Microsoft-provided generic DSM generates a unique identifier from the data that is provided by the storage hardware. MPIO also provides for optionally using a unique hardware identifier assigned by the device manufacturer. MPIO determines which paths to a device are in an active state and can be used for load balancing. The MPIO driver, in combination with the DSM, supports end-to-end path failover.

The process of detecting failed paths and recovering from the failure is automatic, usually fast, and completely transparent to the IT organization. The data ideally remains available at all times. Not all errors result in failover to a new path. When a fatal error occurs, the path is invalidated and a new path is selected. There are two primary types of load-balancing technologies referred to within Windows. This document discusses only MPIO Load Balancing. When addressing data path failover, such as the failover of host bus adapter HBA or iSCSI connections to storage, the following main types of failover are available:.

Different behaviors are available depending on the type of failover technology used, and whether it is combined with a different type of failover or redundancy. Consider the following scenarios:. This scenario provides for either a fault tolerant connection to data, or a load-balanced connection to storage. Since this layer of fault tolerant operation protects only the connectivity between the server and storage, it does not provide protection against server failure. All device-related functionality is initiated by the operating system, but under direct control of subroutines contained within each driver.

These processes are considerably complicated when there are multiple paths to a device. The MPIO software prevents data corruption by ensuring correct handling of the driver associated with a single device that is visible to the operating system through multiple paths. Data corruption is likely to occur because when an operating system believes two separate paths lead to two separate storage volumes, it does not enforce any serialization or prevent any cache conflicts. Consider what would happen if a new NTFS file system tries to initialize its journal log twice on a single volume.

Note that the application and the disk subsystem are not part of the storage layers. When a device such as a storage disk is first added in, each layer of the hierarchy is responsible for making the disk functional such as by adding partitions, volumes, and the file system.

The stack layers below the broken line are collectively known as the device stack and deal directly with managing storage devices. Device drivers manage specific hardware devices, such as a disks or tapes, on behalf of the operating system. Port drivers manage different types of transport, depending on the type of adapter for example, USB, iSCSI, or Fibre Channel in use. Historically, one of the most common port drivers in the Windows system was the SCSIport driver. In conjunction with the class driver, the port driver handles Plug and Play PnP and power functionality.

Port drivers manage the connection between the device and the bus. Windows Server introduced a new port driver, Storport, which is better suited to high-performance, high-reliability environments, and is typically more commonly used today than SCSIport.

Each storage adapter has an associated device driver, known as a miniport. Class drivers manage a specific device type. The class driver manages the functionality of the device. Class drivers like port and miniport drivers are not a part of the MPIO driver package per se; however, the PnP disk class driver, disk. For more information, see the MPIO drivers sections that follow. The MPIO driver is implemented in the kernel mode of the operating system.

It works in combination with the PnP Manager, the disk class driver, the port driver, the miniport driver, and a device-specific module DSM to provide full multipath functionality. Bus drivers are responsible for managing the connection between the device and the host computer.

It acts as the parent bus for the multipath children disk PDOs. The MPIO bus driver also communicates with the rest of the operating system, and manages the PnP connection and power control between the hardware devices and the host computer, and uses WMI classes to allow storage array manufacturers to monitor and manage their storage and associated DSMs.

For more information about WMI, see MPIO WMI Classes http: Management and monitoring of the DSM can be done through the Windows Management Instrumentation WMI interface. A DSM interacts with the MPIO driver. These DSM actions are described further in the following sections. This means that a single server running Windows Server can have multiple DSMs installed on it.

When a new eligible device is detected via PnP, MPIO attempts to determine which DSM is appropriate to handle the device. MPIO contacts each DSM one at a time. The first DSM to claim ownership of the device is associated with that device and the remaining DSMs are not allowed a chance to press claims for that already claimed device. There is no particular order in which the DSMs are contacted, although the Microsoft DSM is always contacted last. If the DSM does support the device, it then indicates whether the device is a new installation, or is the same device previously installed but is now visible through a new path.

In case of a failover, the DSM determines what new path should be used. Продукты Windows Windows Server System Center Microsoft Edge. Office Office Exchange Server. Resources Channel 9 Video Центр пробного ПО Учебные материалы Приложение Microsoft Tech Учебные материалы Microsoft Virtual Academy Центр сценариев Блоги по серверным продуктам и инструментам Блог TechNet. Новостной бюллетень TechNet Галерея TechNet Библиотека TechNet Видео TechNet Wiki Сайт Windows Sysinternals Виртуальные лабораторные занятия.

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Mpio driver

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Продукты Для бизнеса Для разработчиков Для ИТ-специалистов Для технической поддержки Предложения по поддержке. Другие ссылки Microsoft Premier Online Форумы TechNet Форумы MSDN Бюллетени и советы по безопасности. Поддержка для клиентов корпорации Microsoft Форумы Microsoft Community. Главная R2 Библиотека Форумы. Запрошенное содержимое было удалено. Вы будете автоматически перенаправлены через 1 секунду. Understanding MPIO Features and Components. Installing and Configuring MPIO. Adding a Hardware ID for Use with MPIO and Viewing Hidden Devices.

Determining the Hardware ID to Be Managed by MPIO. Enabling Software Tracing for MPIO.

Understanding MPIO Features and Components

Эта документация перемещена в архив и не поддерживается. Understanding MPIO Features and Components Обновлено: Примечание To work with the Microsoft DSM, storage must be SCSI Primary Commands-3 SPC-3 compliant. Application availability through Failover Clustering Clustering is the use of multiple servers, host bus adapters HBAs , and storage devices that work together to provide users with high application availability.

Примечание When using the Microsoft Internet SCSI iSCSI Software Initiator Boot, a maximum of 32 paths to the boot volume is supported. MPIO health reporting The improved MPIO health model enables IT administrators to more efficiently diagnose and gather information about path health by capturing statistical information that can be reviewed in real time or collected over time for trend analysis.

This feature calculates how long paths are down and detects inconsistent failovers. MPIO health reporting uses a collection of statistics that are provided through Windows Management Instrumentation WMI classes. It enables quicker root-cause diagnosis for a failover issue on a server that is connected to external storage through multiple paths. Enhanced configuration of MPIO load-balancing policy settings You can display and configure load-balancing policy settings from the command line by using the MPCLAIM utility. This utility makes configuration of MPIO easier, including scripting the new Least Blocks MPIO load-balancing policy setting, and MPCLAIM enhancements that allow you to more easily script the configuration of MPIO.

It also gives you the ability to configure load-balancing policy settings per disk from the command line, or configure global policies that will be applied to all new MPIO disks. You can also review the text file for troubleshooting or comparison purposes at a later time.

MPIO datacenter automation MPIO datacenter automation allows IT administrators to configure MPIO settings prior to connecting a storage device. To minimize the configuration that is needed after the storage device is connected, you can preconfigure settings such as the default load-balancing policy setting.

Additionally, you can pre-configure MPIO so that when it detects a certain hardware ID, it defaults to a specific load-balancing policy setting. For more information about load-balancing policy settings, see Referencing MPCLAIM Examples. Windows multipathing solutions are required if you want to utilize the MPIO framework to be eligible to receive logo qualification for Windows Server. For additional information about Windows logo requirements, see Windows Quality Online Services Winqual http: This joint solution allows storage partners to design hardware solutions that are integrated with the Windows operating system.

Compatibility with both the operating system and other partner provided storage devices is ensured through the Windows Logo program tests to help ensure proper storage device functionality. This ensures a highly available multipath solution by using MPIO, which offers supportability across Windows operating system implementations. To determine which DSM to use with your storage, refer to information from your hardware storage array manufacturer. Multipath solutions are supported as long as a DSM is implemented in line with logo requirements for MPIO. Most multipath solutions for Windows today use the MPIO architecture and a DSM provided by the storage array manufacturer.

Refer to your storage array manufacturer for information about which DSM to use with a given storage array, as well as the optimal configuration of it. Multipath software suites available from storage array manufacturers may provide an additional value-add beyond the implementation of the Microsoft DSM because the software typically provides auto-configuration, heuristics for specific storage arrays, statistical analysis, and integrated management.

We recommend using the DSM provided by the hardware storage array manufacturer to achieve optimal performance because the storage array manufacturer can make more advanced path decisions in their DSM that are specific to their array, which may result in quicker path failover times. Примечание You might be prompted to restart the computer after the MPIO feature is first installed.

The MPIO driver stack creates a pseudo device for the physical device. The MPIO driver walks through all the available DSMs to determine which vendor-specific DSM can claim the device. After a DSM claims a device, it is associated only with the DSM that claimed it. Примечание In addition to the support for load balancing provided by MPIO, the hardware used must support the ability to use multiple paths at the same time, rather than just fault tolerance.

Differences in load-balancing technologies There are two primary types of load-balancing technologies referred to within Windows. MPIO Load Balancing is a type of load balancing supported by MPIO that uses multiple data paths between server and storage to provide greater throughput of data than could be achieved with only one connection.

Network Load Balancing NLB is a failover cluster technology formerly known as MSCS that provides load balancing of network interfaces to provide greater throughput across a network to the server, and is most typically used with Internet Information Services IIS. When addressing data path failover, such as the failover of host bus adapter HBA or iSCSI connections to storage, the following main types of failover are available: For a server that has one or more HBAs or network adapters, MPIO provides the following: Support for redundant switch fabrics or connections from the switch to the storage array Protection against the failure of one of the adapters within the server directly MPIO-based load balancing In this scenario, multiple paths to storage are also defined; however, the DSM is able to balance the data load to maximize throughput.

This configuration can also employ Fault Tolerant behavior so that if one path fails, all data would follow an alternate path. In some hardware configurations you may have the ability to perform dynamic firmware updates on the storage controller, such that a complete outage is not required for firmware updates. This capability is hardware dependent and requires at a minimum that more than one storage controller be present on the storage so that data paths can be moved off of a storage controller for upgrades.

Failover Clustering This type of configuration offers resource failover at the application level from one cluster server node to another. This type of failover is more invasive than storage path failover because it requires client applications to reconnect after failover, and then resend data from the application layer.

This method can be combined with MPIO-based fault tolerant failover and MPIO-based load balancing to further mitigate the risk of exposure to different types of hardware failures. Consider the following scenarios: Using MPIO without Failover Clustering This scenario provides for either a fault tolerant connection to data, or a load-balanced connection to storage. This configuration provides the following advantages: If a path to the storage fails, MPIO can use an alternate path without requiring client application reconnection.

If an individual server experiences a critical event such as hardware failure, the application managed by Failover Clustering is failed over to another cluster node. While this scenario requires client reconnection, the time to restore the service may be much shorter than that required for replacing the failed hardware. This scenario provides the same benefits as listed in Scenario 2, plus the following benefit: During normal operation, multiple data paths may be employed to provide greater aggregate throughput than one path can provide.

Figure 3 illustrates how devices and path discovery work with MPIO. This policy setting uses a single active path, and the rest of the paths are standby paths. If the active path fails, one of the standby paths is used. When the path that failed is reactivated or reconnected, the standby path can optionally return to standby if failback is turned on. This is the default policy that is chosen when the storage controller follows the active-active model and the management application does not specifically choose a load-balancing policy setting.

The DSM uses paths from active paths for processing requests as long as at least one of the paths is available. The DSM uses a standby path only when all of the active paths fail. A, B, C, and D, paths A, B, and C are listed as active paths and D is the standby path. The DSM chooses a path from A, B, and C in round robin fashion as long as at least one of them is available.

Mpio driver

If all three paths fail, the DSM uses D, the standby path. If paths A, B, or C become available, the DSM stops using path D and switches to the available paths among A, B, and C. The weight indicates the relative priority of a given path. The larger the number, the lower ranked the priority. The DSM chooses the least-weighted path from among the available paths. Ваше мнение очень важно для нас. Подписка на новости Contact Us Конфиденциальность Условия использования Товарные знаки. To work with the Microsoft DSM, storage must be SCSI Primary Commands-3 SPC-3 compliant.

When using the Microsoft Internet SCSI iSCSI Software Initiator Boot, a maximum of 32 paths to the boot volume is supported. You might be prompted to restart the computer after the MPIO feature is first installed. In addition to the support for load balancing provided by MPIO, the hardware used must support the ability to use multiple paths at the same time, rather than just fault tolerance.

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