Actual or real workload
The actual or real workload is the workload the computer system actually performs. Ideally, the actual workload is identical to the business workload.
Alternate Performance Agent
The alternate performance agent is a data collection process based upon user-created specifications (a collection definition) that records performance data. An alternate Performance Agent records user-selected data from the data collected by the primary Performance Agent.
Analysis report
The analysis report is a report that identifies the effects of system parameter settings, hardware configurations, workload mixes, and applications on the performance of any cluster node or the entire cluster. The Analysis report provides conclusions with supporting evidence, and makes recommendations.
Analysis summary
The analysis summary is a short summary appearing in the analysis report after each node analysis. The analysis summary contains the following information:
Archive
Archive is the act of compressing Performance Management daily data records into history file that can be used in place of daily data to create reports, models, and graphs.
Auxiliary knowledge base
The auxiliary knowledge base is a collection of user-defined site-specific rules and thresholds compiled with the rules compiler. The Auxiliary knowledge base rules are used to augment the factory-supplied rules.
Auxiliary rules
Auxiliary rules are the source file containing rules and thresholds that collectively make up the auxiliary knowledge base.
Baseline load
The baseline load is a Performance Management measurements of your existing system or cluster. The baseline load data is stored in a model input file (.MDL).
Baseline model
A baseline model a model generated from historic or daily Performance Management data. The baseline model output provides a workload characterization report. An unmodified. MDL file, the baseline load, represents Performance Management measurements of your existing system. The model generated from this file is known as the baseline model.
Buffered I/O operation
A buffered I/O operation occurs each time an intermediate system buffer is used in place of the process context buffer.
Business
The business is all of the work that is performed on the hardware you are evaluating.
Business workload
Business workload is the work that the business expects its computer to perform is the business workload.
Collection definition
Collection definition is a group of specifications within the schedule file that control a data collection process. These specifications determine which data to collect, when to collect the data, and where to store the data for an individual Performance Agent.
Combined CPU usage chart
The Combined CPU Usage chart is a histogram providing information regarding the use of cluster CPU resources.
Computer system
The computer system is all of the hardware on which business work is performed.
Conclusions
Conclusions are text displayed in an analysis report. See Rule conclusion.
Context block
The context block is an argument block to the Callable Interface For Data Extraction. It contains control information, status information, and addresses of the daily data subrecords. The subrecord fields are also known as data cells.
CPD
The CPD collection definition is provided by default in the schedule file. This set of parameters controls the primary data collector process.
CPU branch explicit
In a modeling context the CPU branch explicit is the probable distribution of load across CPUs for a workload or transaction class. Probabilities must sum to 1. This data is included in the model input file.
Custom graph
A custom graph is a graph type that allows you to specify which Performance Manager data items to graph.
Daily data files
Daily data files are files created by the Performance Agent, one for each node in the cluster, every day. The file name has the following format:
pathname$DATABASE:PSDC$nodename_yyyymmmdd.coll-def-name
Data cell
A data cell is the basic unit of data used to create analysis reports. This data is either retrieved directly from a field in a subrecord of a daily data record or derived from it. The data cell is typically used as a variable in a rule expression.
Data collection error log
The data collection error log is an ASCII file common to the entire cluster called PSDC$DATABASE:PSDC$DC.LOG. Errors that occur during data collection are recorded in the data collection error log file.
Data collection schedule
The data collection schedule is a user-defined schedule by which the Performance Agent records data for nodes in the cluster.
Data collection synchronization
Data collection synchronization is a method used to correlate intervals measured on different nodes within a cluster; those intervals must represent the same real time to make analysis effective.
Data files
Data files are the files from which reports and graphs are constructed. See Daily data files and History files.
Data record
The data record contains OpenVMS performance data written by the Performance Agent. A Performance Agent writes one data record for each interval.
Database directory
The database directory is a directory located on a permanently mounted disk, accessible to every node in the cluster. The data collection process may write the daily data files to this area. Performance Management references this area via the system-wide logical name PSDC$DATABASE.
Device
In the context of the Performance Management, a device is a tape or disk drive. It performs measurable units of work.
Direct I/O
The number of direct I/O operations performed per second. This figure is tallied at the $QIO application interface layer.
Disk branch by source
In a modeling context, the probable distribution of load across disks by originating CPU for a workload or a transaction class is Disk branch by source. Probabilities must sum to 1. This data is included in the model input file.
Disk I/O
Disk I/O is the number of I/O operations per second for the device. This figure is tallied at the physical device driver layer.
Dump report
The dump report contains formatted output of data fields for each record of a Performance Management daily data file or history file.
Evidence
Evidence is text displayed in an analysis report. See Rule evidence.
Factory rules
Factory rules are the performance rules supplied with the Performance Manager in the PSPA$EXAMPLES area in the file named PSPA$KB.VPR.
Family name
Family name is the identifier for a group of workloads, also known as a workload family.
Family type
There are two family types:
Specify either family with the /CLASSIFY_BY qualifier to control use of the family for the reporting facility.
Granularity
Granularity is a Performance Management parameter file element that specifies for each history file descriptor how often a history file is created.
Hard page fault
Hard page fault is an event that occurs each time a process references a virtual page that is not in its working set and requires a read operation from disk.
Histogram
Histogram is an (ASCII) graphic chronological chart showing resource use.
History database
History database contains reduced data from the daily data files, which resides in the history files.
History file
A History file contains data archived from the daily data files. The number of history files created and maintained depends upon the number of history file descriptors and the associated granularity. The file name has the following format:
pathname:PSDC$nodename_dd-mmm-yyyy_dd-mmm-yyyy.name.
History file descriptor
History file descriptor contains the description that the Performance Agent uses to determine how to archive data to the file.
Holidays file
The holidays file contains a list of holiday dates. The Performance Agent uses the holiday schedule on these dates. The file name is PSDC$HOLIDAYS.TXT.
Hot files
Hot files are the most frequently accessed files on each disk. The primary (main) Performance Agent collects hot file data when the length of a disk queue exceeds the HOTFILE_QUEUE setting.
Interaction
An interaction with a device is a two-step process. First, a unit of work to be done (job, user, process, and so forth) enters the queue of the device. Then, the unit of work is serviced by the device (in a manner dependent on the queuing discipline) and departs the device. The concept may be generalized to the system as a whole. The set of device interactions required to process each unit of work is called a transaction.
Interval
In the context of a daily data file, the interval for writing records is the elapsed time between recording.
Journal file
Performance Agent creates one history journal file for each history file. The Journal files are used by the update process in conjunction with the daily data files to recreate corrupt or deleted history files. The file name has the format:
pathname:PSDC$nodename_dd-mmm-yyyy_dd-mmm-yyyy.name_JOU
Do not delete these files. If they exist, they are needed.
Knowledge base
Knowledge base is a file consisting of Performance Manager performance rules used to analyze daily or historic Performance Manager data. It is created with the ADVISE PERFORMANCE COMPILE command from a USER_RULES.VPR file. This data is known as the auxiliary knowledge base.
Measured workload
The measured workload is the workload that can be observed on the system. Ideally, the measured workload is identical to the actual workload, but specified in different terms.
The measured workload is specified by the resource demands that it places on the actual system. These demands, or loadings, are given as the service times of the users at each device along with the number of expected transactions at each device.
MSCP
Mass Storage Control Protocol is a software protocol used to communicate between a host and an intelligent storage controller, or between hosts. In the latter case, one or more hosts serves mass storage devices to other hosts.
OpenVMS cluster
An OpenVMS Cluster is a highly integrated organization of AlphaServer and HP Integrity server system - or VAX and HP AlphaServer system-applications, operating systems, and storage devices.
OTHER
In a modeling context, OTHER is a workload name. All workload families have the catch all workload OTHER to absorb process data that does not match the selection criteria of any defined workload.
Parameters file
The parameters file, PSDC$PARAMS.DAT resides in the PSDC$DATABASE area and serves as a repository for workload characterizations, history file descriptors, and other Performance Management parameters.
Performance Agent
Performance Agent is a detached process that collects and records performance data for each node in the cluster according to a weekly schedule.
Performance evaluation report
The performance evaluation report is a statistical report that helps you determine whether changes that you implemented (based on recommendations in the Analysis Report) improved or degraded system performance.
Periodicity
Periodicity is a parameter file element for a history file descriptor that specifies how often the averaging cycle is restarted.
Predefined graph
A Predefined graph is a graph in that the Performance Manager defines the metrics plotted.
Queue length
Queue length is the average number of outstanding requests, either waiting for or receiving service.
Queuing network model
A queuing network model is a mathematical abstraction of a system in which the computer system is represented as a network of queues. Each queue in the network is evaluated analytically.
Raw data file
See Daily data file.
Recommendation
A recommendation is text presented in an analysis report that offers system tuning advice based on rules firing is recommendation. See Rule conclusion.
Residence time
Residence time is the time, in seconds, between image activation and image termination is residence time. Average time that a request spends wShile waiting for and receiving service.
Response time
Response time is the elapsed time between the arrival of a request and the moment of completion. In the context of modeling, the time between the moment of request arrival at a device and request completion at a device is response time.
Rule
A rule is one or more rule conditions that are evaluated when Performance Manager Analysis reports are generated. Rules are applied to daily or historic data. If all conditions for a rule are true then there is a rule occurrence. Rules are defined to expose areas of potential system problems. See Rule firing.
Rule conclusion
A rule conclusion is a rule element. The rule conclusions are Performance Manager recommendations based on the conclusion text element of a rules file rule construct.
See Rule element.
Rule condition
A rule condition is a rule element. A rule condition is made up of one or more rule expressions. Describes the circumstances which must be true to cause a rule occurrence.
Rule elements
The seven rule elements can exist as the following rule constructs:
Rule evidence
A rule evidence is a rule element. Data satisfying a rule occurrence in a Performance Manager Analysis report. The rule evidence consists of data cell names and values. Typically these data cells are some of those contained in the rule expression.
Rule firing
Rule firing occurs after all the data has been processed, when creating a report, the Performance Manager examines the number of rule occurrences for each rule. If a rule occurrence threshold is met for a particular rule, the rule is said to fire. For each rule that fires an entry is made in the report. The entry may include evidence and conclusions.
Rule identifier
A rule identifier is a rule element. Rule identifier is a five-character alphanumeric code enclosed in braces, one alphabetic character followed by four numeric characters, for example, {M0010} which uniquely identifies the rule.
Rule occurrence
Each time all the rule conditions for a given rule are true, there is one rule occurrence. See Rule firing.
Rules compiler
The rules compiler generates a knowledge base file, (name.KB), from a rules source file (name.VPR)
Rules file
Rules file is a compiled knowledge base file (name.KB). A performance rules source file (name.VPR).
Rules file constructs
The following rules file constructs can exist in a rules file:
Saturation
Saturation is the arbitrary point at which response time at a device becomes substantially higher than the service time.
Schedule file
A schedule file is a file (PSDC$SCHEDULE.DAT) that resides in the PSDC$DATABASE area and controls the recording of Performance Management daily data is Schedule file. A set of parameters (a collection definition) specifies which data to collect, when to collect the data, where to store the data, and how long to keep the data files. The software provides a default set of parameters (the CPD collection definition) and users can create additional collection definitions.
Sensitivity analysis
A sensitivity analysis is a type of “what if” analysis. The act of making small changes in a system model to disclose the areas that are sensitive to these changes.
Service time
Service time is the time required to service a request at a device excluding queuing delay is service time.
Shadow set
A shadow set is one or more compatible physical disk volumes connected together for volume shadowing and represented by a virtual unit. Thus, the term shadow set refers to both the physical unit and the virtual unit.
Soft page fault
Soft page fault occurs each time a process references a virtual page that is not in its working set, but is in memory.
Split I/O
Split I/O is the number of additional physical disk I/O operations required to complete a single user's I/O request, which could not be satisfied in a single I/O to a device.
Summarized
Summarized refers to archived daily data. See History file.
Throughput
Throughput is the number of work units processed per unit of time. The Modeling summary report gives system-wide throughput in terms of transactions per second. The modeling detail report gives throughput in terms of I/Os per second for each component.
TPS
Transactions Per Second is the rate at which transactions arrive to a system.
Transaction
A transaction is a quantifiable unit of work. A transaction typically delineates a single processing step in computer systems.
Transaction class
Transaction class is a group of related transactions. They may be related by the function they perform, by the users who initiate them, or by other quantities you define. Transactions may also be determined by the system resource demands. Performance Management generally refers to a transaction class as a workload.
Transaction class workload
Transaction class workload is a workload that contains at least one image name is transaction class workload.
Transaction workload family
Transaction workload family is set of transaction-based workload definitions.
Usergroup workload family
Usergroup workload family is a set of user-based workload definitions.
User defined graph
See Custom graph.
Utilization
Utilization is the percentage of a resource's capacity being used.
VUP
VUP is a CPU VAX unit of processing rate. The CPU VUP rate measures the power of a system compared to a VAX 11/780. A VAX 11/780 has a VUP rate of 1.0.
Wait Time
Wait time, or queuing time, is the average time each request spends waiting in a queue for service. During this time, the request accomplishes no useful work. Wait time can be derived specifically for each device in the system or for the system as a whole.
Workload
A workload can be one or more users and/or image names. Workload definitions are identified and stored in the Performance Management parameters file. The goal is to express the system's total workload in manageable and meaningful units that Performance Management can report against.
A Transaction workload definition contains at least one image name. Typically, this workload definition contains image names with similar resource demands.
A Usergroup workload contains a user specifier (account name, user name, process name or UIC code). Typically this workload contains a group of users who belong to the same business unit such as a department.
Transaction and Usergroup are terms applied to a workload by the /CLASSIFY_BY qualifier.
Workload family name
Workload family name is a name identifying a group of workloads.
Workload name
Workload name is a name identifying a workload.
Workload selection criteria
The workload selection criteria is the criteria by which process data is assigned to a workload. A workload is selected when process data matches on either or both of a user specifier or image name.
XFC
The Extended File Cache (XFC) is a clusterwide virtual block file system data cache data cache provided with OpenVMS versions 7.3 and up as a replacement for the Virtual I/O cache.
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