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Table of Contents Table of Contents ......................................................................................................................................iii Table of Figures ........................................................................................................................................vii Table of Tables ........................................................................................................................................
Hitachi Data Systems Advanced Cache Algorithms of the Lightning 9900 V Series....................................................................18 Hitachi FlashAccess Software Allows Data Sets to be Permanently Placed in Cache ................................18 Read-ahead for High-performance Sequential Reads ................................................................................18 Control Memory Hierarchical Star Network ...........................................................................
Chapter 9 – Hitachi Freedom Storage Software Solutions Are Best of Breed ______________________33 Hitachi Freedom Storage Software Solutions Simplifies Information Management, Protects Data Assets, and Optimizes Storage Investments ..........................................................................................................33 Storage Area Management Suite ........................................................................................................33 Business Continuity Suite.........
Hitachi Data Systems Chapter 11 – Optimizing Performance, Availability, and Cost with the HiReturn Investment Analysis Tool Kit ________________________________________49 HiReturn Investment Analysis Tool Kit ....................................................................................................49 The HiReturn Methodology Is Implemented in Three Phases ..................................................................49 Phase 1 - Preparation ....................................................
Table of Figures Figure 1 The Lightning 9980V system provides for exploding growth and data hyper-consolidation while the Lightning 9970V system provides for managed growth and open systems exploitation. ............................................................................................2 Figure 2 The Lightning 9900 V Series is based on an internal switched architecture. ........................3 Figure 3 A shared-bus architecture is limited to two simultaneous I/O operations. .................
Hitachi Data Systems Tables viii Table 1 Comparison of Lightning 9900 V Series models. ..................................................................2 Table 2 Bandwidth of supported interfaces of the Lightning 9900 V Series.....................................16 Table 3 System capacities and number of disk drives for various configurations. ............................23 Table 4 Lightning 9980V system bandwidth is ten times that of competition. ................................
Introduction Redefining the Industry Standard, Once Again Hitachi Data Systems, in presenting the Hitachi Freedom Storage™ Lightning 9900™ V Series internal switched storage architecture with virtual Fibre Channel switches, again redefines the industry standard for “best-of-breed” storage systems. It is the most advanced design available in the world for open systems and mainframe data, and it is now two generations ahead of the competition.
Hitachi Data Systems Lightning 9900 V Series Product Offerings The Lightning 9900 V Series offers two models – the Lightning 9980V™ and the Lightning 9970V™. The Lightning 9980V system is recommended for users requiring large storage capacities of 149TB+ of raw storage capacity. With the same advanced architecture as the Lightning 9980V system, the Lightning 9970V system bridges the gap between standard midrange and premium-priced advanced-function storage, with capacities up to 18TB+ of storage.
Introduction An Overview of the Lightning 9900 V Series Architecture The Lightning 9900 V Series intelligent storage systems are the most powerful enterprise systems in the industry today and two generations ahead of the competition. The new architecture used in the Lightning 9900 V Series has almost twice the internal processing power and bandwidth of our earlier enterprise systems. Figure 2 illustrates the architecture of the Lightning 9900 V Series.
Hitachi Data Systems The main components that make up the Lightning 9900 V Series systems are the Array Control Processor modules (ACPs) and Host Adapter modules, called Channel Host Interface Processors (CHIPs). These elements enable the unsurpassed bandwidth of the HiStar network by bringing their own network paths (and bandwidth) to the Cache Hierarchical Star Network (C-HSN) and the Control Memory Hierarchical Star Network (CM-HSN). This means that the full 15.
Introduction • Separate storage for control and configuration tables • Mirrored cache instead of single image cache • Offered by Hitachi Data Systems, the leading supplier of storage systems for geographically GDPS™ production sites • NanoCopy™ technology which offers a scheme for disaster recovery • High-availability, custom-designed disk drives 2 Other Information Sources Available from Hitachi Data Systems Additional information on the enterprise storage market, including an in-depth overview
Hitachi Data Systems Figure 4 – Actual average deployed capacity of the Lightning 9900 V Series systems exceeds that of shared-bus systems by a factor of 2.5x. Second-generation “Virtual” Switched Storage An important key to lower TCO is the Lightning 9900 V Series “virtual” Fibre Channel ports.
Introduction As shown in Figure 6, the heterogeneous solutions of today require the separate configuration of physical ports for each host platform type supported, particularly in high availability path failover and clustered environments. This both increases expense through unnecessary extra ports and limits heterogeneous consolidation, resulting in higher TCO. Figure 6 – Heterogeneous solutions today.
Hitachi Data Systems The Lightning 9900 V Series provides “virtual” Fibre Channel ports that are logically managed by intelligent Fibre Channel controller cards. Each physical Fibre Channel port may have multiple Host Storage Domains. A Host Storage Domain supports a “logical” Fibre Channel port (Fig. 7) each with its own set of LUNs. Hosts are matched to their assigned HSD based on a unique World Wide Names (WWNs) identifier.
Hitachi Freedom Storage™ Lightning 9900™ V Series Packaging 2 The Hitachi Freedom Storage Lightning 9980V™ System Packaging The Lightning 9980V system is available in a two-to-five cabinet configuration (as shown on the cover of this guide), depending on connectivity and capacity needs. A Control Frame serves as the control center of each system and manages up to four Array Frames that are connected via high-speed Fibre Channel links. A fully configured system is contained in five cabinets 73.
Hitachi Data Systems Lightning 9980V System Array Frames Each array frame of the Lightning 9980V system contains up to 256 Hard Disk Drive (HDD) modules and communication interfaces to the Control Frame, for a total of 1024 drives for a maximum configured system. An Array Frame is shown in Figure 9. This design allows for efficient centralized and consolidated storage, which results in reduced management costs and lower overall TCO.
Hitachi Freedom Storage Lightning 9900 V Series Packaging Cables carry 48-volt main system power from the back of the Control Frame and Array Frame where the power is converted to the required voltages. Different AC power cord options allow all Lightning 9900 V Series models to connect with the different electrical outlet configurations used around the world. Figure 10 – Power supply modules for the Lightning 9900 V Series systems.
Hitachi Data Systems Figure 11 – A Lightning 9970V system singlecabinet storage system. The System Monitoring Network of the Lightning 9900 V Series Lightning 9900 V Series systems have both a predictive maintenance and a failure alert system. 12 Lightning 9900 V Series systems are designed with a system-monitoring network.
Front-end Design of the Hitachi Freedom Storage™ Lightning 9900™ V Series 3 CHIPs Support Fibre Channel Host and ESCON® or FICON™ Host Connectivity and Scalability The Lightning 9900 ™ V Series supports both Fibre Channel for open systems and ESCON® or FICON™ for IBM ® S/390®- and zOS ™- compatible platforms as shown in Figure 12. Figure 12 – Fibre Channel and ESCON or FICON adapter boards connect to open systems and mainframe computers.
Hitachi Data Systems About the Fibre Channel Interface Boards Each Fibre Channel Interface Board, as shown in Figure 13, has four Interface Processors for management of connectivity to the host. Each port supports a transfer rate of 2Gbit/sec (gigabits/second) in conformance with the Fibre Channel standard. An optional eight-port Fibre Channel Interface Board is also available. Figure 13 – A 2Gbit/sec Fibre Channel host adapter board and its major hardware components.
Front-end Design of the Hitachi Freedom Storage Lightning 9900 V Series There are four ports for each interface board or a total of 32 host interfaces for a fully configured system. An ESCON interface board is shown in Figure 14. A FICON interface board has a similar appearance. The FICON interface card is available with 1Gbit/sec or 2Gbit/sec transfer rates. Figure 14 – An ESCON host adapter board and its major hardware components.
Hitachi Data Systems Figure 15 – The Lightning 9900 V Series systems support both mainframe and open system hosts. Bandwidth of Supported Host Interfaces The bandwidth of interfaces supported by the Lightning 9900 V Series is shown in Table 2. Table 2 – Bandwidth of supported interfaces of the Lightning 9900 V Series. Supported Interface Bandwidth Fibre Channel Adapters 100MB/sec or 200MB/sec ESCON Adapters 17.
Hi-Star™ Architecture – An Internal Switched Hierarchical Star Network 4 The Internal Hi-Star™ Architecture The internal Hi-Star architecture consists of two separate networks: the Cache Hierarchical Star Network (C-HSN) and the Control Memory Hierarchical Star Network (CM-HSN). The Cache Hierarchical Star Network The C-HSN is the network used for transferring data to and from the main global data cache.
Hitachi Data Systems The Cache Switch Provides Non-blocking Switched Access to Cache The CSW is at the heart of the Lightning 9900 V Series. At the heart of the Lightning 9900 V Series are four Cache Switches (CSWs). Together, these four switches (in the Lightning 9980V ™ system) use a parallel switch fabric bus (PSFB). The CSW is a specially designed crossbar switch that functions as a combination MUX, path arbitrator, and non-blocking network switch.
Hi-Star Architecture – An Internal Switched Hierarchical Star Network mirrored images of each other. This is illustrated in Figure 17. Control data is “data about data,” also called “metadata.” Essentially, control information is handled “out of band” from the data paths, both through a separate memory area and network. The CM-HSN is a much simpler network design in that every connection is a point-to-point connection.
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High-performance Back-end Design 5 High-speed All Fibre Channel Back-end Design Special high-performance back-end drives are available with the Hitachi Freedom Storage™ Lightning 9900 ™ V Series. All the drives are 3.5" Low Profile (LP) 1"-height form factor with capacities available in 36GB, 73GB, and 146GB drives. The 36GB drives spin at 15,000RPM, and the 73GB and 146GB drives spin at 10,000RPM. Each FC-AL path is driven with a dedicated processor.
Hitachi Data Systems Maximum Configuration of ACPs and Disks The maximum configuration of four ACPs and 16 Fibre Channel loops is shown in Figure 19. New Fibre Channel Disk Drives Command Tag Queuing greatly improves performance. The back-end of the Lightning 9900 V Series uses dual ported/dual active Fibre Channel disk drives. All the drives are 3.5" Low Profile (LP) 1"-height form factor with capacities available in 36GB, 73GB, and 146GB drives.
6 Capacities and RAID Architecture Storage Capacity of the Hitachi Freedom Storage™ Lightning 9900™ V Series The Lightning 9900 ™ V Series supports an unmatched range of capacities as shown in Table 3. System Capacities and Number of Disk Drives for Various Configurations Raw System Configuration Raw capacity with 36GB drives Raw capacity with 73GB drives Raw capacity with 146GB drives Lightning 9980V ™ System One Array Frame 9.2TB = 256 disks 18.7TB = 256 disks 37.
Hitachi Data Systems Figure 20 – The Lightning 9900 V Series systems are available with RAID-1+ and RAID-5 arrays. High-density Disk Drive (HDD) Assemblies Each drive has the industry unique feature of supporting dual active ports. 24 The disk drives used in the Lightning 9900 V Series are specially designed for high availability and performance. Each drive has the industry unique feature of supporting dual active ports. This provides significantly increased performance.
Hitachi Freedom Storage™ Lightning 9900™ V Series Availability Is Highest in the Industry 7 An Overview of High-availability (HA) Computing Software It is increasingly important for a business to support continued access to global information 24/7. What’s more, careers often depend on the availability of service levels provided by IT to the enterprise. In computer science, availability refers to the degree to which a system or resource is capable of performing its normal function.
Hitachi Data Systems Hitachi is the only major supplier of enterprise class storage systems with a 100 percent availability guarantee.
Hitachi Freedom Storage Lightning 9900 V Series Availability is Highest in the Industry There are four basic types of high-availability middleware that can reduce downtime in the event of a data path or host failure. The Lightning 9900 V Series supports each classification of middleware: Alternate Pathing Middleware Switches the I/O Load in the Event of Path Failure This type of middleware automatically switches the I/O load on a failed primary path to an alternate path on the same host system.
Hitachi Data Systems Figure 22 - Dynamic Link Manager software automatically provides path failover and load balancing for open systems. Parallel Database Clustering Clustering middleware supports distributed lock management. This type of middleware is a special version of host failover middleware, which supports major parallel database servers like Oracle ® Parallel Server, Informix® XPS, and Sybase ® MPP.
Hitachi Freedom Storage Lightning 9900 V Series Availability is Highest in the Industry Standard Redundant Fans for Cooling The Lightning 9900 V Series provides fully redundant fans for uninterrupted cooling to all components of the system. The speed and operation of these fans are monitored by the environmental monitoring system. If a fan should fail, it can be “hot swapped” without disruption to the cooling system.
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Unmatched Performance and Scalability 8 Truly Scalable Performance Based on the internal switched Hi-Star ™ architecture, the Hitachi Freedom Storage™ Lightning 9900™ V Series shows unmatched performance scalability. This chapter discusses the ability to dramatically add more online transaction processing (OLTP) users and mixed decision-support and OLTP workloads without a user response time decrease.
Hitachi Data Systems Figure 23 –Test results show that the advantages of the Lightning 9980V system maintain user response time while workloads dramatically increase. overshot the targeted transfer rate for the DSS system by approximately 50MB/sec. This was managed by using Hitachi Priority Access software to limit the throughput for a particular application. At this point, the two OLTP workloads were still able to sustain their 2200TPM each, or 4400TPM aggregate.
Hitachi Freedom Storage™ Software Solutions Are Best-of-Breed Customers and analysts regard the Hitachi Freedom Storage™ Lightning 9900™ V Series as the most advanced products in the enterprise storage system market. The Hitachi Freedom Storage Software Solutions Guide (Figure 24) discusses the advantages of the suite of leading-edge software products that enhances the Lightning 9900 V Series product lines. This report is available from Hitachi Data Systems in PDF form at: http://www.hds.com.
Hitachi Data Systems Hitachi Freedom Storage™ Product Support Software Suite ™ Thunder 9531V Thunder 9532V™ Thunder 9533V™ Thunder 9570V™ OS Support Lightning 9900™ V Open IBM® S/390® Storage Area Management Suite Table 5 – Summary of Hitachi Freedom Storage software products.
Hitachi Freedom Storage Software Solutions are Best of Breed policy-driven automated management across the entire life cycle of shared storage services, ranging from planning, implementation, and provisioning, to monitoring. Business Continuity Suite A well-planned business continuity strategy is essential if an organization is to survive planned or unplanned downtime.
Hitachi Data Systems information and performance levels. The Hi-Track "call home" predictive maintenance system is based on intelligent software that monitors a Lightning 9900 V Series system and notifies the Hitachi Data Systems support center for preventative maintenance. Dynamic Link Manager software solution increases information availability by ensuring complete 5 utilization of all paths between a server and a Lightning 9900 V Series system.
Hitachi Freedom Storage Software Solutions are Best of Breed Series’ systems, Priority Access software and Host Storage Domains guarantee that the most crucial applications get the highest level of service. FlashAccess allows users to quickly and easily lock and unlock information into cache in real time. A user can confidently "fill it up and max it out" to meet performance requirements using the maximum raw capacity of the Lightning 9900 V Series system.
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The HiCommand™ Management Framework and Hitachi Resource Manager™ System Management Software 10 A Powerful and Open Systems Management Philosophy The Hitachi Freedom Storage™ Software Solutions support an enterprise’s strategic goal of helping customers focus on their business issues, instead of on deploying enabling technologies, by providing powerful centralized management capabilities.
Hitachi Data Systems Figure 25 – HiCommand Device Manager software and Tuning Manager software allows management of virtually all Hitachi Freedom Storage hardware and software from the customer’s platform of choice. their storage environments than they have ever had in the past. However, most storage managers are faced with administering a myriad of existing components and new, complex storage topologies, which lack a clear and consolidated approach to management.
The HiCommand Management Framework and Hitachi Resource Manager System Management Software based on a combination of Hitachi products and best-of-breed storage hardware and software. Likewise, Device Manager software is customizable to integrate easily with existing infrastructures and accommodate future growth plans. The Device Manager module simplifies management functions and enables integrated administration of multi-vendor storage environments.
Hitachi Data Systems Figure 26 – The HiCommand Management Framework is based on the CIM and SOAP industry standards. common model with which all vendors can work. A CIM-enabled storage management environment will deliver significant benefits to customers, including the ability to: 1.
The HiCommand Management Framework and Hitachi Resource Manager System Management Software Overview of How the Systems Management Software Supports Business Objectives To be successful in today’s business environment, companies must attain the highest levels of business agility, with maximum IT system efficiency and performance. The “storage-centric” model of computing is widely accepted today. In this model “enterprise data” is the most important element of the IT infrastructure.
Hitachi Data Systems systems, and the user’s intranet (public LAN), which allows users to access the Resource Manager software package. 2. SNMP Support Ensures Compliance with All Major Systems-management Platforms The Resource Manager software package supports Simple Network Management Protocol (SNMP). SNMP is the most widely used networkmanagement protocol in the marketplace.
The HiCommand Management Framework and Hitachi Resource Manager System Management Software Figure 27 – Host Storage Domains reduce costs through fewer physical connections. the operating system as a single, large LUN. This capability simplifies storage management because there are fewer LUNs to manage. Two levels of password protection, user and administrator, ensure maximum data security.
Hitachi Data Systems WWN may only be assigned to a single HSD on each Fibre Channel port. SANtinel software may be used to authorize multiple hosts to access a particular HSD. SANtinel software may be further used to permit or deny a particular host to access individual LUNs within the HSD, based upon the WWN of the host. SANtinel software may be used to create up to 128 HSDs per physical Fibre Channel port.
The HiCommand Management Framework and Hitachi Resource Manager System Management Software performed at cache speeds, with no disk latency delay. With FlashAccess software, a portion of cache memory can be allocated to specific data. Users can add, delete, or change FlashAccess software managed data at any time, quickly and easily. Defined by the LUN for open systems, cache data can be as small as a single track or as large as an entire volume.
Hitachi Data Systems Figure 29 – The GUI interface on Graph-Track software simplifies performance management. scrutinizes activity all the way to the logical-device level, reporting on channelinterface-processor usage rates, cache-usage rate by function, and logical-device utilization. This data pinpoints specific activities that may have a negative impact on operations, and lets the user fine-tune the system so that it can be used to maximum advantage.
11 Optimizing Performance, Availability, and Cost with the HiReturn™ Investment Analysis Tool Kit HiReturn™ Investment Analysis Tool Kit Most enterprises today require that financial investment analysis be prepared prior to IT capital expenditures. Identifying hardware and software as "best-of-breed" is no longer sufficient justification for a major investment.
Hitachi Data Systems Phase 3 – Final report. The HiReturn team provides a business Financial Impact Report that summarizes the ROI findings of the assessment and outlines the suggested strategy, along with other key recommendations. The On-site Assessment Produces the Needed Facts to Build a Business Case The HiReturn analysis is conducted at the customer’s site.
Global Solutions Services Hitachi Data Systems Is Consistently Ranked Number One in the Industry 12 In numerous independent surveys on IT services organizations, Hitachi Data Systems continually wins the highest ratings in terms of overall customer satisfaction.
Hitachi Data Systems Global Solutions Services team start by uncovering the complexity of an individual organization’s storage environment in order to define a baseline deployment. Using baseline objectives, the consultants then plan and implement a PATHLINE management environment. In the course of the engagement, product overview training is provided and training of key administrators on the newly customized PATHLINE configuration concludes the service.
Global Solutions Services Hitachi SplitSecond ™ Solutions Rapid Recovery Service for Microsoft® Exchange The Hitachi SplitSecond™ Solutions Rapid Recovery Service for Microsoft ® Exchange employs hardware and software in a service package that is designed to solve business problems that can be avoided by the rapid recovery for mission-critical applications or databases in the event of a failure.
Hitachi Data Systems Infrastructure Planning Service for FICON ™ The Hitachi Data Systems Infrastructure Planning Service for FICON ™ is an on-site, implementation planning and training start up service designed to accelerate the installation of a FICON solution. This service also helps protect current data center infrastructure investments by leveraging the current, physical environment and by projecting long-term growth requirements associated with the FICON migration.
Glossary of Terms 10BaseT Ethernet with a data transfer rate of 10Mbits/sec. 100BaseT Also known as Fast Ethernet with a data transfer rate of 100Mbits/sec. AG Array Group. ACP Array Control Processor. The group of processors on a PCB that performs the physical access of the disk drives across four FC-AL loops. ACP Pair A combination of two ACPs, designed in such a manner as to facilitate redundancy and performance.
Hitachi Data Systems Availability In computer science, availability refers to the degree to which a system or resource is capable of performing its normal function. Availability is measured in terms of Mean Time Between Failure (MTBF) divided by MTBF plus the Mean Time to Repair (MTTR). The availability equation is expressed as follows: AVAILABILITY = MTBF / (MTBF+MTTR).
Glossary CHA Channel Host Adapter. CHIP Channel Host Interface Processor. C–HSN Cache Hierarchical Star Network. CHT Channel adapter Tachyon (for Fibre Channel interfaces). Client/Server Architecture Client/Server Architecture is a network architecture in which each computer or processor on the network is either a client or a server. Servers are powerful computers or processors dedicated to managing disk drives (file servers), printers (print ser vers), or network traffic (network servers).
Hitachi Data Systems CTQ Command-Tag Queuing. DA The Data Adapter resides on the CHT and connects the cache boards to the front end. DAS Direct Attached Storage. Data Availability Data availability refers to the degree to which a computer system is capable of providing data to its users. See also Availability. Data Copy A term that refers to remote copy, data duplication, and data migration. DD Disk Director. Data Duplication Software that duplicates data as in remote copy or point-in-time (PiT) snapshots.
Glossary DRR Data Recovery and Regeneration. DSS Decision Support Systems is a term that refers to computer systems used in the areas of business intelligence, such as data warehousing, data mining, OLAP, and others. DTA Data Adapter. ECC Error correction code. ESA/390® Enterprise Systems Architecture/390 ®. Often abbreviated S/390 ®, ESA/390 is an IBM® architecture for mainframe computers and peripherals. Processor systems that follow this architecture include the IBM ES/9000® family.
Hitachi Data Systems eXtended SCSI Copy (e-Copy) Extended SCSi is a command in the SCSI 3 specification that allows for the transfer of data without the involvement of the server. The Hitachi Freedom Storage™ Lightning 9900™ V Series implements this command, which is used by programs such as VERITAS® NetBackup™ to enable serverless and LANfree backup. Fabric A fabric is one of three Fibre Channel topologies. In a Fabric topology, Node Ports (N_Ports) are connected to Fabric Ports (F_Ports) on a switch.
Glossary Freedom Data Networks™ Hitachi Data Systems groups its storage area network (SAN) and network attached storage (NAS) solutions under the label Freedom Data Networks. Freedom Data Networks provides an open architecture that leverages SAN and NAS technology and offers organizations freedom of choice in deploying data-access and data-sharing capabilities across the enterprise through Hitachi Data Systems advanced implementations: Hitachi Freedom SAN ™ and Hitachi Freedom NAS™.
Hitachi Data Systems Gigabit Ethernet Provides a standard that supports data transfer at 1000Mbit/sec. Gigabit Ethernet is also called 1000BaseT Category 5 (copper wire) or 1000BaseX (fiber optic). There is a 10,000BaseT version of the Ethernet standard that will be widely available by early 2003. GUI GUI is an acronym that refers to a Graphical User Interface, which is the software that controls the screen presented to a user in a computer application.
Glossary Hitachi Dynamic Link Manager ™ Dynamic Link Manager is a server-based family of software utilities that enhances RAID systems by providing automatic failover and load balancing from server-toRAID channel connection failures. This product allows systems administrators to take advantage of the multiple paths on a Lightning 9900 V Series system by adding redundant SCSI connections between data servers and RAID systems. Dynamic Link Manager therefore provides increased reliability and performance.
Hitachi Data Systems Hitachi Multiplatform Resource Sharing Multiplatform Resource Sharing is built right into the Lightning 9900 V Series systems. With Multiplatform Resource Sharing, Lightning 9900 V Series systems users can share resources between UNIX ® or Microsoft® Windows NT®/Windows® 2000 servers and S/390 mainframe platforms.
Glossary Hitachi TrueCopy™ TrueCopy provides synchronous or asynchronous remote copy capability for open system and S/390 computers. This allows remote copies over virtually unlimited distances. Operating systems that are supported include IBM MVS®, HP/UX, AIX, Sun Solaris, Digital UNIX, Sequent DYNIX/ptx, SGI IRIX, NCR, UNIX SVR4, and Windows NT/Windows 2000. Host Storage Domain One or more Host Storage Domains may be defined on each Fibre Channel port on the Lightning 9900 V Series.
Hitachi Data Systems InterSan® Pathline® InterSAN Inc.’s Storage Area Management (SAM) software product PATHLINE is the first application-based SAM software that aligns the management of storage networks with business policies and objectives. PATHLINE helps customers efficiently manage large, multiprotocol, multivendor storage area networks (SANs) by taking an applications-oriented view that masks the complexity of the underlying storagenetworking infrastructure.
Glossary Logical Unit Number See LUN. Logical Volume The storage medium associated with a logical disk drive. A logical volume typically resides on one or more storage devices. A host system sees a logical volume as a physical volume, although it does not correlate directly with a physical disk drive. LUN Logical Unit or Logical Unit Numbers. A SCSI term for the field in an identifying message that is used to select a logical unit on a given target.
Hitachi Data Systems Metadata Data about data as used by the CM-HSM and the Control Memory Subsystem of the Lightning 9900 V Series. Mirrored Pair Two disk units or logical units that contain the same data. The operating system software refers to them as one entity and “reads from either” and “writes to both” when RAID-1 is enabled. Mirroring A term to describe the process of writing data to two disk volumes, usually to ensure high availability in case one of the disks fails.
Glossary NDMP Network Data Management Protocol (NDMP) is a standard protocol for networkbased backup of network-attached storage. NDMP hides the unique hardware interfaces from third-party backup software that allows this software to execute on any NDMP compliant system on the network. Node See Fibre Channel. NVM Non-volatile Memory is a term used to refer to battery backed up DRAM so that data will not be lost in the event of power failure.
Hitachi Data Systems Operating system The operating system is the most important software program that runs on a computer. The operating system (OS) performs basic tasks such as recognizing input from a keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices, such as disk drive and printers or a mouse. The OS acts as a traffic cop and schedules the various programs that the computer executes.
Glossary RAID Redundant Array of Independent Disks. RAID is used to increase the reliability of disk arrays by providing redundancy either through complete duplication of the data (RAID-1, i.e., mirroring) or through construction of parity data for each data stripe in the array (RAID-3, -4, -5). RAID-5, which distributes parity information across all disks in an array, is among the most popular means of providing parity RAID since it avoids the bottlenecks of a single parity disk.
Hitachi Data Systems SCSI Small Computer System Interface. An intelligent bus-level interface that defines a standard I/O bus and a set of high-level I/O commands. There are currently many flavors of SCSI defined by different bus widths and clock speeds. The seven major variations of SCSI are SCSI 1, SCSI 2 (Fast/Narrow), SCSI 2 (Fast/Wide), Ultra SCSI (Fast/Narrow), Ultra SCSI (Fast/Wide) – also called SCSI 3, Ultra 2 SCSI (Narrow), Ultra 2 SCSI (Wide). See also Fibre Channel.
Glossary Switch A switch is a network device that examines and forwards packets between LAN segments. Synchronous Synchronous communications occur when the transmission of data between two devices is synchronized with a clocking scheme or other technique. The sender and receiver need to synchronize with one another before data is sent.
Hitachi Data Systems Volume An IBM® ESA/390® term for the information recorded on a single disk unit or recording medium. Indirectly, a volume can refer to the unit of recording medium itself. On a non-removable medium storage device such as a disk drive, the terms may also refer, indirectly, to the storage device that is associated with the volume. When a user stores multiple volumes on a single storage medium transparent to the program, the volumes are referred to as logical volumes.
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