EMC QLogic manual

Introduction

Understanding Persistent Binding in a Fabric Environment

Persistent binding is the mechanism to create a continuous logical route from a storage device object in the Windows host to a volume in the EMC® storage array across the fabric.

Without a persistent binding mechanism, the host cannot maintain persistent logical routing of the communication from a storage device object across the fabric to an EMC storage array volume. If the physical configuration of the switch is changed (for example, the cable is swapped or the host is rebooted), the logical route becomes inconsistent, causing possible data corruption if the user application is modifying data through inconsistent logical routing of the communication from the driver entry point to a volume in an EMC storage array across the fabric.

The Windows NT/Windows 2000/Windows 2003 operating system (OS) does not provide a satisfactory means to allow persistent binding. Most software applications access storage using file systems that are managed by the Windows OS. (File systems are represented by drive letters: C:, D:, and so forth.) For storage devices containing file systems, Windows NT/Windows 2000 writes a disk signature to the disk device. The OS can then identify and associate with a particular drive letter and file system.

Because the disk signature resides on the disk device, changes can occur on the storage end (a cable swap, for example) that can cause a disk device to be visible to the host server in a new location. However, the OS looks for the disk signature and, providing that nothing on the disk changed, associates the signature with the correct drive letter and file system. This mechanism is strictly an OS feature and is not influenced by the Fibre Channel device driver.

Some software applications, however, do not use the Windows file systems or drive letters for their storage requirements. Instead they access storage drives directly, using their own built-in “file systems.” Devices that are accessed in this way are referred to as raw devices and are known as physical drives in Windows terminology.

The naming convention for physical drives is simple and is always the same for software applications using them. A raw device under Windows NT/Windows 2000/Windows 2003 is accessed by the name \\PHYSICALDRIVEXXX, where XXX is the drive number. For example, a system with three hard disks attached using a QLogic Fibre Channel controller assigns the disks the names

1-2	EMC Fibre Channel with QLogic HBAs in the Windows Environment

QLogic specifications

EMC QLogic is a leading provider of advanced networking solutions, primarily known for its high-performance storage area network (SAN) technologies. It specializes in Fibre Channel and Ethernet networking products, offering robust solutions that are essential for modern data center environments.

One of the key features of EMC QLogic is its exceptional performance in high-speed data transfer. QLogic's Fibre Channel products, such as switches and host bus adapters (HBAs), support speeds of up to 32 Gbps, ensuring ultra-fast communication between storage devices and servers. This high throughput is crucial for applications demanding high IOPS (Input/Output Operations Per Second), particularly in virtualized environments and databases.

Another prominent aspect of EMC QLogic's technology is its support for advanced features like Data Center Bridging (DCB). DCB enables the convergence of storage and traditional Ethernet traffic on a single network, streamlining data center management and reducing costs. By allowing both storage and data networking to coexist on the same infrastructure, EMC QLogic enhances efficiency and simplifies network architecture.

Scalability is another characteristic that sets EMC QLogic apart. The architecture is designed to support a wide range of deployment sizes, from small businesses to large enterprise data centers. This scalability ensures that organizations can grow their IT infrastructure without needing to overhaul their existing deployment.

EMC QLogic also places a strong emphasis on reliability and security. Their products are built with redundancy and failover mechanisms, which minimize downtime and ensure continuous operation even in the event of hardware failure. Additionally, security features such as encryption and access controls are integrated to protect sensitive data as it travels across the network.

Management and monitoring capabilities are also integral to EMC QLogic's offerings. The company provides advanced software tools for managing network resources, allowing administrators to monitor performance, diagnose issues, and optimize configurations efficiently. This helps organizations maintain peak performance and reduces operational complexity.

In summary, EMC QLogic combines high-speed performance, advanced features, and robust reliability in its networking solutions. With a focus on scalability and security, it provides organizations with the tools necessary to build and manage efficient, modern data centers that can adapt to evolving technological demands. Its commitment to innovation positions EMC QLogic as a trusted partner in the storage networking landscape.