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76-421: Unlike other mainframe systems, BS2000 provides exactly the same user and programming interface in all operating modes (batch, interactive and online transaction processing) and regardless of whether it is running natively or as a guest system in a virtual machine . This uniformity of the user interface and the entire BS2000 software configuration makes administration and automation particularly easy. Currently, it

152-399: A centralized data storage model, but with its own data network . A SAN is, at its simplest, a dedicated network for data storage. In addition to storing data, SANs allow for the automatic backup of data, and the monitoring of the storage as well as the backup process. A SAN is a combination of hardware and software. It grew out of data-centric mainframe architectures , where clients in

228-468: A high-level programming language (compared to the low-level ISA abstraction of the system VM). Process VMs are implemented using an interpreter ; performance comparable to compiled programming languages can be achieved by the use of just-in-time compilation . This type of VM has become popular with the Java programming language , which is implemented using the Java virtual machine . Other examples include

304-590: A CIM object manager (CIMOM), to manage objects and interactions, and allows for the central management of SAN storage devices. Basic device management for SANs can also be achieved through the Storage Management Interface Specification (SMI-S), were CIM objects and processes are registered in a directory. Software applications and subsystems can then draw on this directory. Management software applications are also available to configure SAN storage devices, allowing, for example,

380-457: A LUN, these would interfere with each other and quickly corrupt the data. Any planned sharing of data on different computers within a LUN requires software. File systems have been developed to work with SAN software to provide file-level access . These are known as shared-disk file system . Video editing systems require very high data transfer rates and very low latency. SANs in media and entertainment are often referred to as serverless due to

456-402: A SAN are said to form the storage layer . It can include a variety of hard disk and magnetic tape devices that store data. In SANs, disk arrays are joined through a RAID which makes a lot of hard disks look and perform like one big storage device. Every storage device, or even partition on that storage device, has a logical unit number (LUN) assigned to it. This is a unique number within

532-420: A SAN as "a network whose primary purpose is the transfer of data between computer systems and storage elements". But a SAN does not just consist of a communication infrastructure, it also has a software management layer . This software organizes the servers, storage devices, and the network so that data can be transferred and stored. Because a SAN does not use direct attached storage (DAS), the storage devices in

608-441: A SAN provides only block-level access, file systems built on top of SANs do provide file-level access and are known as shared-disk file systems . Newer SAN configurations enable hybrid SAN and allow traditional block storage that appears as local storage but also object storage for web services through APIs. Storage area networks (SANs) are sometimes referred to as network behind the servers and historically developed out of

684-478: A nested guest virtual machine does not need to be homogeneous with its host virtual machine; for example, application virtualization can be deployed within a virtual machine created by using hardware virtualization . Nested virtualization becomes more necessary as widespread operating systems gain built-in hypervisor functionality, which in a virtualized environment can be used only if the surrounding hypervisor supports nested virtualization; for example, Windows 7

760-413: A network can connect to several servers that store different types of data. To scale storage capacities as the volumes of data grew, direct-attached storage (DAS) was developed, where disk arrays or just a bunch of disks (JBODs) were attached to servers. In this architecture, storage devices can be added to increase storage capacity. However, the server through which the storage devices are accessed

836-431: A normal application inside a host OS and supports a single process. It is created when that process is started and destroyed when it exits. Its purpose is to provide a platform -independent programming environment that abstracts away details of the underlying hardware or operating system and allows a program to execute in the same way on any platform. A process VM provides a high-level abstraction – that of

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912-527: A particular architecture does not provide hardware support required for nested virtualization, various software techniques are employed to enable it. Over time, more architectures gain required hardware support; for example, since the Haswell microarchitecture (announced in 2013), Intel started to include VMCS shadowing as a technology that accelerates nested virtualization. Storage area network A storage area network ( SAN ) or storage network

988-673: A popular approach to implementing early microcomputer software, including Tiny BASIC and adventure games, from one-off implementations such as Pyramid 2000 to a general-purpose engine like Infocom 's z-machine , which Graham Nelson argues is "possibly the most portable virtual machine ever created". Significant advances occurred in the implementation of Smalltalk -80, particularly the Deutsch/Schiffmann implementation which pushed just-in-time (JIT) compilation forward as an implementation approach that uses process virtual machine. Later notable Smalltalk VMs were VisualWorks ,

1064-568: A precursor of online transaction processing . In 1977, the TRANSDATA communication system used computer networking . In 1978, multiprocessor technology was introduced. The operating system had the ability to cope with a processor failure. At the same time the new technology considerably extended the performance range of the system. In 1979, a transaction processing monitor , the Universal Transaction Monitor (UTM),

1140-573: A request to read or write data, it will check its access list to establish whether the node, identified by its LUN, is allowed to access the storage area, also identified by a LUN. LUN masking is a technique whereby the host bus adapter and the SAN software of a server restrict the LUNs for which commands are accepted. In doing so LUNs that should never be accessed by the server are masked. Another method to restrict server access to particular SAN storage devices

1216-440: A segregated address space for the programs of different users. From the outset TSOS also allowed data peripherals to be accessed only via record- or block-oriented file interfaces, thereby preventing the necessity to implement device dependencies in user programs. The same operating system was also sold to Sperry Univac when it bought most of RCA's computer division. Univac's " fork " of TSOS would become VS/9 , which used many of

1292-451: A specific programming language, but are embedded in an existing language; typically such a system provides bindings for several languages (e.g., C and Fortran ). Examples are Parallel Virtual Machine (PVM) and Message Passing Interface (MPI). Both system virtual machines and process virtual machines date to the 1960s and remain areas of active development. System virtual machines grew out of time-sharing , as notably implemented in

1368-520: A switch provides a dedicated link to connect all its ports with one another. When SANs were first built, Fibre Channel had to be implemented over copper cables, these days multimode optical fibre cables are used in SANs. SANs are usually built with redundancy, so SAN switches are connected with redundant links. SAN switches connect the servers with the storage devices and are typically non-blocking allowing transmission of data across all attached wires at

1444-607: A system virtual machine can be considered a generalization of the concept of virtual memory that historically preceded it. IBM's CP/CMS , the first systems to allow full virtualization , implemented time sharing by providing each user with a single-user operating system, the Conversational Monitor System (CMS). Unlike virtual memory, a system virtual machine entitled the user to write privileged instructions in their code. This approach had certain advantages, such as adding input/output devices not allowed by

1520-413: Is a computer network which provides access to consolidated, block-level data storage . SANs are primarily used to access data storage devices, such as disk arrays and tape libraries from servers so that the devices appear to the operating system as direct-attached storage . A SAN typically is a dedicated network of storage devices not accessible through the local area network (LAN). Although

1596-488: Is a single point of failure , and a large part of the LAN network bandwidth is used for accessing, storing and backing up data. To solve the single point of failure issue, a direct-attached shared storage architecture was implemented, where several servers could access the same storage device. DAS was the first network storage system and is still widely used where data storage requirements are not very high. Out of it developed

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1672-493: Is also used to implement the "guest" environments, and applications running in a given "guest" environment view it as a stand-alone system. The pioneer implementation was FreeBSD jails ; other examples include Docker , Solaris Containers , OpenVZ , Linux-VServer , LXC , AIX Workload Partitions , Parallels Virtuozzo Containers, and iCore Virtual Accounts. A snapshot is a state of a virtual machine, and generally its storage devices, at an exact point in time. A snapshot enables

1748-463: Is an example of such snapshots. Restoring a snapshot consists of discarding or disregarding all overlay layers that are added after that snapshot, and directing all new changes to a new overlay. The snapshots described above can be moved to another host machine with its own hypervisor; when the VM is temporarily stopped, snapshotted, moved, and then resumed on the new host, this is known as migration. If

1824-548: Is capable of running Windows XP applications inside a built-in virtual machine. Furthermore, moving already existing virtualized environments into a cloud, following the Infrastructure as a Service (IaaS) approach, is much more complicated if the destination IaaS platform does not support nested virtualization. The way nested virtualization can be implemented on a particular computer architecture depends on supported hardware-assisted virtualization capabilities. If

1900-603: Is fabric-based access control, or zoning, which is enforced by the SAN networking devices and servers. Under zoning, server access is restricted to storage devices that are in a particular SAN zone. A mapping layer to other protocols is used to form a network: Storage networks may also be built using Serial Attached SCSI (SAS) and Serial ATA (SATA) technologies. SAS evolved from SCSI direct-attached storage. SATA evolved from Parallel ATA direct-attached storage. SAS and SATA devices can be networked using SAS Expanders . The Storage Networking Industry Association (SNIA) defines

1976-719: Is mainly used in Germany - making up to 83% of its total user base - as well as in the United Kingdom (8%), Belgium (4.8%) and other European countries (4.2%). BS2000 has its roots in the Time Sharing Operating System (TSOS) first developed by RCA for the /46 model of the Spectra/70 series, a computer family of the late 1960s related in its architecture to IBM 's /360 series . It was an early operating system which used virtual addressing and

2052-606: Is often used on top of the Fibre Channel switched fabric protocol in servers and SAN storage devices. The Internet Small Computer Systems Interface (iSCSI) over Ethernet and the Infiniband protocols may also be found implemented in SANs, but are often bridged into the Fibre Channel SAN. However, Infiniband and iSCSI storage devices, in particular, disk arrays, are available. The various storage devices in

2128-449: Is the process of abstracting logical storage from physical storage. The physical storage resources are aggregated into storage pools, from which the logical storage is created. It presents to the user a logical space for data storage and transparently handles the process of mapping it to the physical location, a concept called location transparency . This is implemented in modern disk arrays, often using vendor-proprietary technology. However,

2204-723: The CP-40 and SIMMON , which used full virtualization , and were early examples of hypervisors . The first widely available virtual machine architecture was the CP-67 /CMS (see History of CP/CMS for details). An important distinction was between using multiple virtual machines on one host system for time-sharing, as in M44/44X and CP-40, and using one virtual machine on a host system for prototyping, as in SIMMON. Emulators , with hardware emulation of earlier systems for compatibility, date back to

2280-582: The Compatible Time-Sharing System (CTSS). Time-sharing allowed multiple users to use a computer concurrently : each program appeared to have full access to the machine, but only one program was executed at the time, with the system switching between programs in time slices, saving and restoring state each time. This evolved into virtual machines, notably via IBM's research systems: the M44/44X , which used partial virtualization , and

2356-554: The IBM System/360 in 1963, while the software emulation (then-called "simulation") predates it. Process virtual machines arose originally as abstract platforms for an intermediate language used as the intermediate representation of a program by a compiler ; early examples date to around 1964 with the META II compiler-writing system using it for both syntax description and target code generation. A notable 1966 example

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2432-547: The Parrot virtual machine and the .NET Framework , which runs on a VM called the Common Language Runtime . All of them can serve as an abstraction layer for any computer language. A special case of process VMs are systems that abstract over the communication mechanisms of a (potentially heterogeneous) computer cluster . Such a VM does not consist of a single process, but one process per physical machine in

2508-680: The Security evaluation to F2/Q3 was completed. From 1992 through 1995, BS2000/OSD V1.0 was made open to application software and was renamed BS2000/OSD (Open Server Dimension). Full support of the XPG4 standard was achieved in 1995 after the porting of the POSIX interfaces in 1992. In 1996, BS2000/OSD was ported to the MIPS architecture . Although the operating system ran on different hardware architectures (S servers with /390 architecture and SR2000 servers for

2584-592: The Squeak Virtual Machine , and Strongtalk . A related language that produced a lot of virtual machine innovation was the Self programming language, which pioneered adaptive optimization and generational garbage collection . These techniques proved commercially successful in 1999 in the HotSpot Java virtual machine. Other innovations include a register-based virtual machine, to better match

2660-404: The network-attached storage (NAS) architecture, where one or more dedicated file server or storage devices are made available in a LAN. Therefore, the transfer of data, particularly for backup, still takes place over the existing LAN. If more than a terabyte of data was stored at any one time, LAN bandwidth became a bottleneck. Therefore, SANs were developed, where a dedicated storage network

2736-402: The 'host', and the virtual machine emulated on that machine is generally referred to as the 'guest'. A host can emulate several guests, each of which can emulate different operating systems and hardware platforms. The desire to run multiple operating systems was the initial motive for virtual machines, so as to allow time-sharing among several single-tasking operating systems. In some respects,

2812-658: The Fujitsu Siemens Computers' SX server line. In 2004, support for storage area networks based on Fibre Channel technology was introduced. In 2006, BS2000/OSD V7.0 introduced support for new server generations, Unicode support, and improved SAN integration. In 2008, BS2000/OSD was ported to the x86 architecture , and the SQ server line was introduced. In 2012, BS2000/OSD version 9.0 was released. Pilot release of version 10.0 started in November 2014, and it

2888-643: The IBM CP-40 and CP-67 , predecessors of the VM family. Examples outside the mainframe field include Parallels Workstation , Parallels Desktop for Mac , VirtualBox , Virtual Iron , Oracle VM , Virtual PC , Virtual Server , Hyper-V , VMware Fusion , VMware Workstation , VMware Server (discontinued, formerly called GSX Server), VMware ESXi , QEMU , Adeos , Mac-on-Linux, Win4BSD, Win4Lin Pro , and Egenera vBlade technology. In hardware-assisted virtualization,

2964-571: The MIPS architecture), applications produced for /390 can be used on computers based on MIPS architecture without recompilation due an emulation layer for legacy code. In 1997, WebTransactions allowed applications to use the Internet . In 1999, BS2000/OSD was the first operating system to be awarded Internet Branding by The Open Group . In 2002, BS2000/OSD was ported to the SPARC architecture, leading to

3040-406: The SAN are not owned and managed by a server. A SAN allows a server to access a large data storage capacity and this storage capacity may also be accessible by other servers. Moreover, SAN software must ensure that data is directly moved between storage devices within the SAN, with minimal server intervention. SAN management software is installed on one or more servers and management clients on

3116-412: The SAN devices from other vendors. In a SAN, data is transferred, stored and accessed on a block level. As such, a SAN does not provide data file abstraction, only block-level storage and operations. Server operating systems maintain their own file systems on their own dedicated, non-shared LUNs on the SAN, as though they were local to themselves. If multiple systems were simply to attempt to share

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3192-491: The SAN, and they convert digital bits into light impulses that can then be transmitted over the Fibre Channel cables. Conversely, the GBIC converts incoming light impulses back into digital bits. The predecessor of the GBIC was called gigabit link module (GLM). The fabric layer consists of SAN networking devices that include SAN switches , routers, protocol bridges, gateway devices, and cables. SAN network devices move data within

3268-402: The SAN, or between an initiator , such as an HBA port of a server, and a target , such as the port of a storage device. When SANs were first built, hubs were the only devices that were Fibre Channel capable, but Fibre Channel switches were developed and hubs are now rarely found in SANs. Switches have the advantage over hubs that they allow all attached devices to communicate simultaneously, as

3344-402: The SAN, so-called SAN servers are used, which in turn connect to SAN host adapters . Within the SAN, a range of data storage devices may be interconnected, such as SAN-capable disk arrays, JBODS and tape libraries . Servers that allow access to the SAN and its storage devices are said to form the host layer of the SAN. Such servers have host adapters, which are cards that attach to slots on

3420-463: The SAN. Every node in the SAN, be it a server or another storage device, can access the storage by referencing the LUN. The LUNs allow for the storage capacity of a SAN to be segmented and for the implementation of access controls. A particular server, or a group of servers, may, for example, be only given access to a particular part of the SAN storage layer, in the form of LUNs. When a storage device receives

3496-445: The VM continues operation from the last-known coherent state, rather than the current state, based on whatever materials the backup server was last provided with. Nested virtualization refers to the ability of running a virtual machine within another, having this general concept extendable to an arbitrary depth. In other words, nested virtualization refers to running one or more hypervisors inside another hypervisor. The nature of

3572-457: The VM for a location on its physical disk are transparently translated into an operation on the corresponding file. Once such a translation layer is present, however, it is possible to intercept the operations and send them to different files, depending on various criteria. Every time a snapshot is taken, a new file is created, and used as an overlay for its predecessors. New data is written to the topmost overlay; reading existing data, however, needs

3648-449: The cluster. They are designed to ease the task of programming concurrent applications by letting the programmer focus on algorithms rather than the communication mechanisms provided by the interconnect and the OS. They do not hide the fact that communication takes place, and as such do not attempt to present the cluster as a single machine. Unlike other process VMs, these systems do not provide

3724-447: The configuration of zones and LUNs. Ultimately SAN networking and storage devices are available from many vendors and every SAN vendor has its own management and configuration software. Common management in SANs that include devices from different vendors is only possible if vendors make the application programming interface (API) for their devices available to other vendors. In such cases, upper-level SAN management software can manage

3800-411: The developmental stage, so it runs inside a sandbox . Virtual machines have other advantages for operating system development and may include improved debugging access and faster reboots. Multiple VMs running their own guest operating system are frequently engaged for server consolidation. A process VM, sometimes called an application virtual machine , or Managed Runtime Environment (MRE), runs as

3876-525: The functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination of the two. Virtual machines differ and are organized by their function, shown here: Some virtual machine emulators, such as QEMU and video game console emulators , are designed to also emulate (or "virtually imitate") different system architectures, thus allowing execution of software applications and operating systems written for another CPU or architecture. OS-level virtualization allows

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3952-931: The hardware provides architectural support that facilitates building a virtual machine monitor and allows guest OSes to be run in isolation. Hardware-assisted virtualization was first introduced on the IBM System/370 in 1972, for use with VM/370 , the first virtual machine operating system offered by IBM as an official product. In 2005 and 2006, Intel and AMD provided additional hardware to support virtualization. Sun Microsystems (now Oracle Corporation ) added similar features in their UltraSPARC T-Series processors in 2005. Examples of virtualization platforms adapted to such hardware include KVM , VMware Workstation , VMware Fusion , Hyper-V , Windows Virtual PC , Xen , Parallels Desktop for Mac , Oracle VM Server for SPARC , VirtualBox and Parallels Workstation . In 2006, first-generation 32- and 64-bit x86 hardware support

4028-445: The host bus adapter (HBA). If a device is connected to the SAN its WWN is registered in the SAN switch name server. In place of a WWN, or worldwide port name (WWPN), SAN Fibre Channel storage device vendors may also hardcode a worldwide node name (WWNN). The ports of storage devices often have a WWN starting with 5, while the bus adapters of servers start with 10 or 21. The serialized Small Computer Systems Interface (SCSI) protocol

4104-408: The nature of the configuration which places the video workflow (ingest, editing, playout) desktop clients directly on the SAN rather than attaching to servers. Control of data flow is managed by a distributed file system. Per-node bandwidth usage control, sometimes referred to as quality of service (QoS), is especially important in video editing as it ensures fair and prioritized bandwidth usage across

4180-540: The network. SAN Storage QoS enables the desired storage performance to be calculated and maintained for network customers accessing the device. Some factors that affect SAN QoS are: Alternatively, over-provisioning can be used to provide additional capacity to compensate for peak network traffic loads. However, where network loads are not predictable, over-provisioning can eventually cause all bandwidth to be fully consumed and latency to increase significantly resulting in SAN performance degradation. Storage virtualization

4256-416: The older snapshots are kept in sync regularly, this operation can be quite fast, and allow the VM to provide uninterrupted service while its prior physical host is, for example, taken down for physical maintenance. Similar to the migration mechanism described above, failover allows the VM to continue operations if the host fails. Generally it occurs if the migration has stopped working. However, in this case,

4332-486: The overlay hierarchy to be scanned, resulting in accessing the most recent version. Thus, the entire stack of snapshots is virtually a single coherent disk; in that sense, creating snapshots works similarly to the incremental backup technique. Other components of a virtual machine can also be included in a snapshot, such as the contents of its random-access memory (RAM), BIOS settings, or its configuration settings. " Save state " feature in video game console emulators

4408-421: The resources of a computer to be partitioned via the kernel . The terms are not universally interchangeable. A "virtual machine" was originally defined by Popek and Goldberg as "an efficient, isolated duplicate of a real computer machine." Current use includes virtual machines that have no direct correspondence to any real hardware. The physical, "real-world" hardware running the VM is generally referred to as

4484-440: The same computer (e.g., Windows , Linux , or prior versions of an operating system) to support future software. The use of virtual machines to support separate guest operating systems is popular in regard to embedded systems . A typical use would be to run a real-time operating system simultaneously with a preferred complex operating system, such as Linux or Windows. Another use would be for novel and unproven software still in

4560-616: The same concepts. In 1973, BS2000 V1.0 was a port of the TSOS operating system to models of the Siemens system 7.700 In June 1975, Siemens shipped the enhanced BS2000 V2.0 version of the TSOS operating system for the models of the Siemens 7.700 mainframe series for the first time under the name BS2000. This first version supported disk paging and three different operating modes in the same system: interactive dialog, batch, and transaction mode,

4636-453: The same physical page by a technique termed kernel same-page merging (KSM). This is especially useful for read-only pages, such as those holding code segments, which is the case for multiple virtual machines running the same or similar software, software libraries, web servers, middleware components, etc. The guest operating systems do not need to be compliant with the host hardware, thus making it possible to run different operating systems on

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4712-414: The same time. SAN switches are for redundancy purposes set up in a meshed topology . A single SAN switch can have as few as 8 ports and up to 32 ports with modular extensions. So-called director-class switches can have as many as 128 ports. In switched SANs, the Fibre Channel switched fabric protocol FC-SW-6 is used under which every device in the SAN has a hardcoded World Wide Name (WWN) address in

4788-402: The server motherboard (usually PCI slots) and run with a corresponding firmware and device driver . Through the host adapters the operating system of the server can communicate with the storage devices in the SAN. In Fibre channel deployments, a cable connects to the host adapter through the gigabit interface converter (GBIC). GBICs are also used on switches and storage devices within

4864-415: The standard system. As technology evolves virtual memory for purposes of virtualization, new systems of memory overcommitment may be applied to manage memory sharing among multiple virtual machines on one computer operating system. It may be possible to share memory pages that have identical contents among multiple virtual machines that run on the same physical machine, what may result in mapping them to

4940-405: The storage devices. Two approaches have developed in SAN management software: in-band and out-of-band management. In-band means that management data between server and storage devices is transmitted on the same network as the storage data. While out-of-band means that management data is transmitted over dedicated links. SAN management software will collect management data from all storage devices in

5016-622: The storage layer. This includes info on read and write failures, storage capacity bottlenecks and failure of storage devices. SAN management software may integrate with the Simple Network Management Protocol (SNMP). In 1999 Common Information Model (CIM), an open standard, was introduced for managing storage devices and to provide interoperability, The web-based version of CIM is called Web-Based Enterprise Management (WBEM) and defines SAN storage device objects and process transactions. Use of these protocols involves

5092-520: The underlying hardware, rather than a stack-based virtual machine, which is a closer match for the programming language; in 1995, this was pioneered by the Dis virtual machine for the Limbo language. In full virtualization, the virtual machine simulates enough hardware to allow an unmodified "guest" OS (one designed for the same instruction set ) to be run in isolation. This approach was pioneered in 1966 with

5168-429: The virtual machine's state at the time of the snapshot to be restored later, effectively undoing any changes that occurred afterwards. This capability is useful as a backup technique, for example, prior to performing a risky operation. Virtual machines frequently use virtual disks for their storage; in a very simple example, a 10- gigabyte hard disk drive is simulated with a 10-gigabyte flat file . Any requests by

5244-660: The virtual machine, notably in UCSD Pascal (1978); this influenced later interpreters, notably the Java virtual machine (JVM). Another early example was SNOBOL4 (1967), which was written in the SNOBOL Implementation Language (SIL), an assembly language for a virtual machine, which was then targeted to physical machines by transpiling to their native assembler via a macro assembler . Macros have since fallen out of favor, however, so this approach has been less influential. Process virtual machines were

5320-782: Was attached to the LAN, and terabytes of data are transferred over a dedicated high speed and bandwidth network. Within the SAN, storage devices are interconnected. Transfer of data between storage devices, such as for backup, happens behind the servers and is meant to be transparent. In a NAS architecture data is transferred using the TCP and IP protocols over Ethernet . Distinct protocols were developed for SANs, such as Fibre Channel , iSCSI , Infiniband . Therefore, SANs often have their own network and storage devices, which have to be bought, installed, and configured. This makes SANs inherently more expensive than NAS architectures. SANs have their own networking devices, such as SAN switches. To access

5396-427: Was found to rarely offer performance advantages over software virtualization. In OS-level virtualization, a physical server is virtualized at the operating system level, enabling multiple isolated and secure virtualized servers to run on a single physical server. The "guest" operating system environments share the same running instance of the operating system as the host system. Thus, the same operating system kernel

5472-479: Was introduced, providing support for online transaction processing as an additional operating mode. In 1980, Siemens introduced the system 7.500 hardware family, ranging from desk size models for use in office environments to large models with water cooling. In 1987, BS2000 V9.0 was ported to the /370 architecture supported 2GB address spaces , 512 processes and the XS channel system (Dynamic Channel Subsystem). BS2000

5548-479: Was popularized around 1970 by Pascal , notably in the Pascal-P system (1973) and Pascal-S compiler (1975), in which it was termed p-code and the resulting machine as a p-code machine . This has been influential, and virtual machines in this sense have been often generally called p-code machines. In addition to being an intermediate language, Pascal p-code was also executed directly by an interpreter implementing

5624-570: Was released in May 2015. Pilot release of version 11.0 started in March 2017, and it was released in July 2017. Pilot release of version DX V1.0(v21.0) started in March 2021, and it was released in July 2021. Virtual machine In computing , a virtual machine ( VM ) is the virtualization or emulation of a computer system . Virtual machines are based on computer architectures and provide

5700-522: Was subdivided into subsystems decoupled from one another. With the advent of the VM2000 virtual machine in 1990, multiple BS2000 systems, of the same or different versions, can run in parallel on the same computer. The hierarchical storage management system (HSMS) swapped out infrequently used data to cheaper storage media. When the data is needed again, it is restored to high-speed access media. The ROBAR tape archiving system supported robot systems. In 1991,

5776-548: Was the O-code machine , a virtual machine that executes O-code (object code) emitted by the front end of the BCPL compiler. This abstraction allowed the compiler to be easily ported to a new architecture by implementing a new back end that took the existing O-code and compiled it to machine code for the underlying physical machine. The Euler language used a similar design, with the intermediate language named P (portable). This

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