Definitions of Acronyms and Terms

• CPC/CEC - Central Processor Complex/Central Electronics Complex - the 'box' with processors/memory/etc.
• CP/CPUs - Central Processor Unit - does the processing within a CPC/CEC (also called engines).
• CP(GP) - General Purpose processor - this is for most VM systems work (CP and general purpose are the same).
• CP(IFL) - Integrated Facility for Linux Processor - special engine for less expensive Linux processing.
• CP(ZIIP) - Zseries Integrated Information Processor - specialty offload engine usually for z/OS or Java.
• vCPU - virtual Central Processor Unit - represents a portion or share of the underlying physical CPU.
• CPU Processor Utilization - a percentage number based on CPU seconds divided by wall clock time. These all are synonymous with processor utilization - processor busy, processor load, CPU utilization, CPU load and CPU busy.
• DASD Fast Write - Provides support for the caching of write requests. A write is held on the storage control unit cache until the data is written to disk. Greatly improves performance.
• DAT - DAT - Direct Address Translation - translating a virtual address into a physical address in memory.
• DCSS - DisContiguous Saved Segment - saves a portion of storage that can be shared between multiple guests which all see the same storage. An example would be the ZMON DCSS segment.
• DPA - Dynamic Paging Area - what is left of system storage (memory) for use after the control program has defined what it needs.
• DSA - Dynamic Storage Areas in CICS - storage areas made from virtual storage pages taken from system storage subpools. In 24-bit mode the areas are CICS DSA (CDSA), User DSA (UDSA), Shared DSA (SDSA) and Read-only DSA (RDSA). In 31-bit mode the areas are Extended CICS DSA (ECDSA), Extended user DSA (EUDSA), Extended shared DSA (ESDSA), extended read-only DSA (ERDSA) and Extended trusted DSA (ETDSA). In 64-bit mode the areas are above-the-bar CICS DSA (GCDSA), above-the-bar user DSA (GUDSA) and above-the-bar shared DSA (GSDSA).
• FBA DASD - Fixed Block Arcitecture Direct Access Storage Device - A large "hard drive" that holds data.
• FCP - Fibre Channel Protocol - the SCSI interface protocol utilizing an underlying Fibre Channel connection. It provides in-order, lossless delivery of raw block data, connecting many different devices to storage devices.
• FEPI - Front End Programming Interface - a CICS interface to write CICS applications that simulate terminals to access other CICS or IMS programs.
• IBR - Invalid but Resident - this refers to pages in storage on the global aging list. This is new with z/VM 6.3 and helps replace XSTORE (expanded storage).
• ILMT - IBM License Metric tool - allows for subcapacity pricing.
• IRLM - Db2 Internal Resource Lock Manager - works with Db2 to control access to data.
• IUCV - Inter User Communication Vehicle is a data transfer mechanism that allows point to point communication channels between two virtual machines or between a virtual machine and hypervisor services in z/VM.
• LAN - Local Area Network - a group of two or more connected computers in a small geographical area.
• LPAR - Logical PARtition is a subset of the processor hardware - CPC/CEC's can be divided into multiple LPARs. In practice, LPARs are equivalent to separate mainframes.
• MAC Address - Media Access Control - a 48-bit unique address that is given by the manufacturer to a hardware component inside the CPU known as the NIC (Network Interface Card). It connects a device wirelessly to the internet.
• MDC Minidisk Cache - memory used to keep frequently used minidisk information instead of writing to disk.
• MIB - Management Information Base - a collection of manageable network objects. MIBs contain information about the configuration of network components that can be managed using SNMP.
• MTU - Maximum Transmission Unit - is the size of the largest protocol data unit that can be communicated in a single network layer transaction.
• NIC - Network Interface Card - a hardware component needed to connect to a network.
• Nice Value - A value used for Linux to control the CPU priority of a process. Values range from -20 (highest) to +19 (lowest) with 0 as the default.
• NSS - Named Saved Systems - saves a portion of an operating system that is IPL'd frequently to improve IPL performanceon z/VM. An example would be the CMS NSS.
• NVS - Nonvolatile storage (NVS) is random access storage with an electronic backup. This maintains system data integrity for DASD fast write data not yet written to DASD.
• OSA - Open System Adapter - a network controller installed on an IBM mainframe I/O cage. It supports many network transport protocols used in communication. It also supports an integrated console controller (OSA-ICC).
• PR/SM - Processor Resource/System Manager - This is the partitioning hypervisor on a CEC. It is responsible from a hardware perspective for managing the box. It is used to create and run LPARs.
• PCI - Peripheral Component Interconnect - a local computer bus (high speed connection) for attaching hardware devices in a computer.
• RLF - Resource Limit Facility - a governor that limits specific Db2 resources that can be consumed by dynamic SQL. The two modes used by RLF are reactive and predictive.
• RLS - Record-level sharing - an access mode for VSAM datasets supported by DFSMS 1.3 and later releases.
• RNI - Relative Nest Intensity - calculations (per John Burg at WSC) of how many cycles it takes data to be retrieved from the different levels of cache on a CEC (minus Address Translation). For z15 processors or higher, this number is calculated on ESAMFCA.
• QDIO - Queued Direct Input/Output - a highly efficient data transfer architecture which improves data transfer speed and efficiency for TCPIP traffic. QDIO mode is reffered to as OSD because the channel path id (CHPID) type coded is OSD.
• SAP - System Assistance Processor - a SAP will execute internal code to provide information to the I/O subsystem - such as device address translation, control unit addresses and device numbers - to aid in performance.
• SCSI - Small Computer System Interface - a set of standard electronic interfaces that allow personal computers to communicate with peripheral hardware such as disk drives, etc.
• SMT - Simultaneous MultiThreading is a processor design that combines hardware multithreading with superscalar processor technology.
  Simultaneous multithreading enables z/VM to dispatch work on an individual thread of an IFL core, allowing a core to be shared by multiple guest CPUs or z/VM control program tasks.
• SNMP - Simple Network Managment Protocol -a way for different devices on a network to share information.
• SRM - System Resource Manager is used to set different system parameters such as polorization, dispatch time slice, etc.on z/VM.
• Storage - in a CPC/CEC box it is also called memory. This allows direct access to storage for read/write operations as opposed to serial access memory such as tape or disk, etc.
• TCPIP - Transmission Control Protocol/Internet Protocol - a set of standardized rules that all computers to communicate on a network. It specifies how data is exchanged over the network.
• TLB - Translation Lookaside Buffer - memory cache closer to the CPU which can reduce the time taken to repeatedly access a page table.
• VDISK - Virtual Disk - a shared memory object or data space that acts like disk but is in memory.
• WAS - Websphere Application Server - A secure Java server runtime environment for enterprise applications.