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HP OpenVMS Systems Documentation

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The OpenVMS Frequently Asked Questions (FAQ)


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2.15 What resources are available to OpenVMS software developers?



GThe HP Developer and Software Product Partner (DSPP) program is open toCand intended to support and to assist HP OpenVMS software partners,#consultants, and service providers:



GDSPP provides members with various benefits, please see the website fordetails.

EFor those not familiar with the DSPP program or with its history, theGDIGITAL Association of Software and Application Partners (ASAP) programCand the DIGITAL Independent Software Vendors Network (ISVN) programFwere incorporated into the Compaq CSA program, and the CSA program has8subsequently been incorporated into the HP DSPP program.

{Please see Section 2.8.3 for additional details on the DSPP program.|

2.16 memory management, resource management, process scheduling, etc?



?So you have been instructed to write a school research paper onEOpenVMS, and you need technical content on the OpenVMS Virtual MemoryFSystem, on any memory segmentation, on OpenVMS Resource Management, on<the OpenVMS File System, on the OpenVMS user interface, etc.

FInvariably, your professor/instructor/teacher will ask you a series ofDquestions. Most commonly, the questions will request descriptions ofDone or more of the following items, and at varying levels of detail:

    %
  • process scheduling algorithm(s)
  • Interprocess comunications2
  • Process or system synchronization constructs<
  • Memory management and/or virtual memory implementation
  • RMS or XQP file structures
  • Resource management
  • History of HP OpenVMSE
  • History of Compaq and/or of Digital Equipment Corporation (DEC)


AAny particular presentation or research paper, and particularly aAscholastic presentation, can have many different potential targetEaudiences, and very different presentation levels. Further, the usualFunderlying reason for scholastic presentations and scholastic researchFprojects really has little to do with the subject matter, it is a taskFspecifically intended to teach the student(s) (eg: you) how to perform@the research. The instructor already knows most of (all of?) the0information that you have been asked to collect.

EFor very technical details on OpenVMS and OpenVMS internals, the bookFyou want is the Internals and Data Structures Manual (IDSM), availableDin your school or computing center library, and the IDSM can also beGpurchased. Additional technical details of the Alpha microprocessor areGavailable in the Alpha Architecture Reference Manual documentation thatEis available for download. (Pointers to Alpha technical documentationdare available in Section 14.6, and elsewhere.)

DFor higher-level (less technical) details, the OpenVMS documentationGset is available on-line. The Programming Concepts and the File SystemsDmanual are probably the best manuals to start with, depending on the1particular level of detail the research requires.

DAnd please understand the hesitation of various folks to provide youFwith a completely-written research report on your topic. Why? We mightBhave to work with you after you graduate---you need to know how toEperform at least basic research on your own, regardless of the topic.W

2.17 Basic Units of Measurement?



DOpenVMS and the underlying hardware use various units of measurementEfor disk and memory storage, and related abbreviations also typicallyDexist. This section covers the most common units, and the associatedabbreviations.H

2.17.1 How many bytes are in a disk block?



GA disk block is the minimum unit of disk storage allocation in OpenVMS.

BUnder OpenVMS VAX and OpenVMS Alpha, the disk volume block size is1consistent, with each block containing 512 bytes.

DThe minimum disk allocation granularity actually permissible (in the>ODS-2 and ODS-5 volume structures commonly used on OpenVMS) is=determined on a per-volume basis, and is typically based on aGcombination of the total number blocks on the disk volume and the totalFsize of the volume storage bitmap. The allocation granularity is knownBas the volume cluster factor---the cluster factor is the number ofFblocks in a disk cluster, and it is the smallest number of blocks that-can be allocated on a particular disk volume.

APrior to OpenVMS V7.2, the maximum permissible size of the bitmapGrequires larger cluster factors as volume sizes increase. Starting withCV7.2, the bitmap can be larger, and cluster factors as small as oneblock can be used.

BThe number of bytes in a file can be determined by multiplying theFnumber of blocks allocated for the file times the number of bytes in aCblock. For sequential files (only), the FFB (XAB$W_FFB, in the File>Header XAB) value can be used to find out how much of the last>(XAB$L_EBK) block is used. FFB and EBK are meaningful only for?sequential files, and only in a limited context---partial blockEallocations are not permitted. For other file formats, the EOF markeris not meaningful.

CDisk allocations always occur only in units of the cluster factors,Dwhich can be from one block up to (potentially) clusters of eighteenEblocks or more, depending on the volume cluster factor. (OpenVMS V7.2Fand later optionally provide for a cluster factor of one up to volumes of approximately 137 gigabytes.)

AOpenVMS assumes that the device driver and the underlying storageEdevice will present the file system with addressable units of storageDof 512 bytes in size, or the appearance of same. Various third-partyECD-ROM devices, for instance, support only 2048 byte blocks, and suchBdevices are incompatible with the standard OpenVMS device drivers.

BTo determine the number of bytes required for a file from DCL, oneGoption uses the f$file_attributes item EOF, multiplied by the size of aGblock in bytes (512). This does not account for the unused space in the=last block of a sequential file, but it also does not have to0differentiate sequential files from other files.I

2.17.2 How many bytes are in a memory page?



GA memory page is the minimum unit of memory allocation in OpenVMS. WithDOpenVMS VAX, the memory page size matches the disk block size: it isalways 512 bytes.

FWith OpenVMS Alpha, the memory page size is variable, and it can rangeDfrom 8192 bytes (8 kilobytes) up to 64 kilobytes. The current systemFpage size can be determined using the sys$getsyi or f$getsyi PAGE_SIZEDitem. Programs with hardcoded constants for the memory page size (orApage alignment) should always assume a page size of 64 kilobytes.

COn OpenVMS I64, the memory page size is also variable, ranging fromG4096 bytes (4 kilobytes) up to 256 megabytes (MB) and potentially up toD4 gigabytes (GB). As with OpenVMS Alpha, sys$getsyi and f$getsyi andFthe PAGE_SIZE itemcode can and should be used to determine the currentCsystem page size. In general, OpenVMS I64 will use a page size of 8kilobytes, or larger.

AOn OpenVMS Alpha and on OpenVMS I64, a 512 byte area of memory---Fequivalent in size to an OpenVMS VAX memory page---is often refered toas a "pagelet".U

2.17.3 How do I convert? Disk Blocks? KB, MB, GB, TB?



DThe smallest granularity of disk storage addressing is called a diskDblock, or sometimes a disk sector. Groups of disk blocks are usually@organized together into the smallest unit of storage that can beGallocated, and this unit is called a disk cluster. The number of blocksDin a cluster is the cluster factor, and is established when the diskvolume is initialized.

CEach individual disk block is composed of five hundred twelve (512)Dbytes, or one-half kilobyte. Each byte is comprised of eight bits. AEbit represents the smallest unit of information, typically refered toas a one or a zero.

DOpenVMS tends to uses base two notation for disk storage, while disk>storage capacity specifications from most storage vendors will generally use base ten notation.

EAn OpenVMS disk block is 512 bytes in size; this is one-half kilobytein base two notation.

CThe following table describes the prefix, the abbreviation, and theEassociated base ten (as used by marketing and by storage vendors) and>base two (OpenVMS and various other operating systems) values.

 

"
5          Base Ten                           Base TwoF          --------------------------------   -------------------------FKilobyte  (KB)  10**3                 1000   2**10                1024FMegabyte  (MB)  10**6              1000000   2**20             1048576FGigabyte  (GB)  10**9           1000000000   2**30          1073741824FTerabyte  (TB)  10**12       1000000000000   2**40       1099511627776FPetabyte  (PB)  10**15    1000000000000000   2**50    1125899906842624FExabyte   (EB)  10**18 1000000000000000000   2**60 1152921504606846976




FThe base ten representation of the 2**40 value is 1099511627776, whichEis obviously rather ugly. When viewed as a base eight or base sixteenC(octal or hexadecimal, respectively) value, the value is far nicer.GSpecifically, the value is 10000000000 and 40000000 when represented in$octal and hexadecimal, respectively.



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FAQ6 Notation

DWithin the OpenVMS FAQ, a thousand bits (either assuming base two or:base ten, as determined by the context) is refered to as aC kilobit, and is always represented by the appreviation Kb, while a" thousand bytes is refered to as aH kilobyte and is always abbreviated as KB. Similar notational usage also holds for Megabits (Mb) and9 Megabytes (MB), and for the various other units.


GOpenVMS operating system references to system and storage are generally?to the base-two version (eg: 1024, in the case of a kilobyte orFkilobit) while storage hardware references and hardware specifications1are generally to the base-ten version (eg: 1000).

@To convert OpenVMS disk blocks to (base two) kilobytes (KB; 1024=bytes), simply divide by two. To convert blocks to (base two)Fmegabytes, divide by 2048. Blocks to (base two) gigabytes (GB), divideBby 2097152. These particular divisions can also be performed usingEbitshifts: to divide a value by two, shift the binary value rightwardby one bit position.

ATo convert OpenVMS disk blocks to (base ten) kilobytes, divide byapproximately 1.953125.

FFor those folks with an interest in odd applications for prefixes, andBparticularly for those folks also rummaging around deep within the*OpenVMS operating system, a microfortnight is approximately one second.


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3.1 Where can I find online copies of OpenVMS manuals?



BThe HP OpenVMS and HP Layered Product documentation is copyrighted material.

FHTML format on-line product documentation sets for specific HP OpenVMS$products are presently available at:



GDocumentation is offered on separately orderable CD-ROM media through aGsubscription to the Consolidated On-Line Documentation (ConOLD) producty(see Section 2.6.) ConOLD manuals are readable with BNU, a viewer thatFis supplied with the documentation distribution. BNU can display HTML,/Bookreader, and documentation in other formats.

EMGBOOK, a viewer for Bookreader-format documentation is available forBcharacter-cell terminals (eg. VTxxx) via the WKU VMS Freeware filedserver -- see question Section 13.1 for details.

FInformation on the XPDF DECwindows PDF viewer for OpenVMS is availabletin Section 13.1, and XPDF kits are available on various FreewareFdistributions. An alternative on OpenVMS Alpha uses the Adobe Java PDFDviewer, though this viewer is generally considered to be both slower=and more resource-intensive when compared to the XPDF viewer.Om

3.2 What online information and websites are available?

t

_@On your OpenVMS system, the HELP command can provide a wealth ofBinformation, not only on DCL commands but on system services (HELPGSystem_Services) and Run-Time Library routines (HELP RTL_Routines). Thec=introduction displayed when you type the HELP command with nop.additional keywords provides further pointers.

t`OpenVMS Marketing runs a web server at #http://www.hp.com/go/openvms/ a

nHere, you will find product information, strategy documents, product roadmaps, the contents of the latest OpenVMS Freeware CD-ROM and more.

0[ h  "   t s " 0 o d i e  v 1 p m t  o  e  a p  f   n h q h x >   f = r m x  e u e e r r u n  c   r l > e  a u a l s  h  n l e t A c i e l # F m t t c e u  r u  l   1 1 k  S n o m   b t r s o  e t  t b e e n e l o o  h c l c e y s V i n  a p n  t b  s  r i A i  8  o i a ( o G y    n V e a s 2 l > = d 2 = 1 > / m i 1 i h o  u  s e o o a t i .  t t  r =   -  4  4   0 0 0 / e n p 0 b g  o  a n s t / l m x d r  r e  t
Table 3-1 OpenVMS Websites
URL Sponsor
r HP OpenVMS Marketing
  \ http://www.hp.com/go/openvms/
< Encompass DFWCUG
  @ % http://www.openvmshobbyist.org/c
a Arne Vajhøj
  Z http://www.levitte.org/~ava/
s Saiga Systemss
  L http://www.saiga.com/
d Wayne Sewell
  T http://www.tachysoft.com/
e proGIS Software>
  A u& http://www.progis.de/openvms.htm
e Jeff Cameron
  Z http://www.jcameron.com/vms/
> David Mathog's (quite useful) information about OpenVMS.
  I . http://saf.bio.caltech.edu/soft_doc.html
, Crackingl
e "The Beave"pJ
Includes system cracking information that can be of interest toL OpenVMS System Managers, and to OpenVMS Network and Security Managers.< This information is available at the Deathrow cluster.
  O e4 http://manson.vistech.net/ht_root/Hack-VMS-faq
a, Undocumented Features
f DECUS Deutschland
  U e: http://zinser.no-ip.info/www/eng/vms/qaa/undoc.htmlx
n Arne Vajhøj
  J / http://www.levitte.org/~ava/vms_tip.htmlxe
M The OpenVMS Freeware contains various examples of undocumented featuresn and interfaces
  G m, http://www.hp.com/go/openvms/freeware/
xC Comparisons of UNIX and Linux shell commands and DCL Commandse
  T 9 http://www.mcsr.olemiss.edu/unixhelp/VMStoUNIX.html-
  Y u> http://wwwvms.mppmu.mpg.de/vmsdoc/UNIX_VMS_CMD_XREF.HTML
h; Comparisons of emacs and OpenVMS text editor commandsc
   D http://www.unh.edu/cis/docs/vms-to-unix/Emacs/cheat-sheet.html
f% Bibliographiesc
  L 1 http://www.openvms.org/pages.php?page=Booksi
  K f0 http://www.levitte.org/~ava/vms_book.htmlx
.# Introductorya
  Please see Table 3-2 for listings of introductory web sites ands related materials.
b" Programming
b An OpenVMS Programming FAQ
   F http://www.pdv-systeme.de/users/martinv/VMS_Programming_FAQ.html
! Networkingu
I Tutorial information and tips for connecting OpenVMS systems to the  Internet
  @ % http://www.tmesis.com/internet/e
kB Documentation and Specifications for DECnet Phase IV, DECnet6 task-to-task DCL examples, and a whole lot more.
  E e* http://www.hp.com/go/openvms/wizard/
M/ HP OpenVMS Documentationi
  Please see Table 3-2 for listings of documentation web sites and related materials.
) System Performancex
  L See Section 14.2.
>' Patch (ECO) Kitsd
  H For the HP Services FTP server hosting Various contract-access andz non-contract access ECO (patch) kits, see section Section 5.17.
d+ Catalogs and Pricinge
o3 HP Product QuickSpecs and product informationo
  F + http://www.hp.com/go/productbulletin/
i6 The HP Systems and Options Catalog (SOC) archive
   http://h18000.www1.hp.com/products/4
quickspecs/soc_archives/SOC_Archives.html
5 Hardware and Software Archives
-A The VAXarchive, including hardware and software information*
  E a* http://vax.sevensages.org/index.html
x" A VAX to Alpha upgrade diary
  W < http://www3.sympatico.ca/n.rieck/docs/alpha_diary.html
t9 Scanned versions of old DIGITAL manuals from DFWCUGe
  K o0 http://www.montagar.com/~patj/dec/hcps.htm
mA A wide variety of HP VAX, Alpha, platform and other producta7 documentation. Some introductory, some technical.s
  Z ? http://h18000.www1.hp.com/support/techpubs/qrg/index.htmli
/! dtrwiz's Datatrieve websitel
  ^ http://dtrwiz.home.netcom.com/
s

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3.1 Where can I find online copies of OpenVMS manuals?

Index

 

#r6h7in 1977. VAX/VMS Version V1.0;shipped in 1978, along with the first revenue-ship 11/780s.

COpenVMS was designed entirely within HP and specifically within theDformer Digital Equipment Corporation (DIGITAL). Two of the principal@designNOtP.HTDOCS.OPENVMS.WHITEPAPERS.SERVERCONSOLIDATION'9X6PIXEL.JPG;BEAVIS DISK$WEB3 .2CB(y筗A0ALPHA.JPG;BEAVIS DISK$WEB3 .2CB(y筗B0COMPAQ.JPG;BEAVIS DISK$WEB3 .2CB(y筗B0INDEX.HTML;BEAVIS DISK$WEB3 .2CB(y筗G#/_2'9X6PIXEL.JPG;BEAVIS DISK$WEB3 .2CB(y筗A2ALPHA.JPG;BEAVIS DISK$WEB3 .2CB(y筗B2COMPAQ.JPG;BEAVIS DISK$WEB3 .2CB(y筗B2INDEX.HTML;BEAVIS DISK$WEB3 .2CB(y筗 S/TCO_CLUSTERS'HPWEB_META.INC;BEAVIS DISK$WEB3 .2CB(y筗 H$)TCO_WP_FEB04.PDF;BEAVIS DISK$WEB3 .2CB(y筗 J&ECHCLUS'IMAGES.DIR;BEAVIS DISK$WEB3 .2CB(y筗 A&NDEX.HTML;BEAVIS DISK$WEB3 .2CB(y筗