=;The OpenVMS Frequently Asked Questions (FAQ)D

The OpenVMS Frequently Asked Questions (FAQ)



 r \ ^  
PreviousContentsIndex

x

2.15 What resources are available to OpenVMS software developers?



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



HDSPP provides members with various benefits, please see the website for details.

FFor those not familiar with the DSPP program or with its history, the HDIGITAL Association of Software and Application Partners (ASAP) program Dand the DIGITAL Independent Software Vendors Network (ISVN) program Gwere incorporated into the Compaq CSA program, and the CSA program has 8subsequently been incorporated into the HP DSPP program.

kPlease 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 on FOpenVMS, and you need technical content on the OpenVMS Virtual Memory GSystem, on any memory segmentation, on OpenVMS Resource Management, on <the OpenVMS File System, on the OpenVMS user interface, etc.

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



BAny particular presentation or research paper, and particularly a Bscholastic presentation, can have many different potential target Faudiences, and very different presentation levels. Further, the usual Gunderlying reason for scholastic presentations and scholastic research Gprojects really has little to do with the subject matter, it is a task Gspecifically intended to teach the student(s) (eg: you) how to perform Athe research. The instructor already knows most of (all of?) the 0information that you have been asked to collect.

FFor very technical details on OpenVMS and OpenVMS internals, the book Gyou want is the Internals and Data Structures Manual (IDSM), available Ein your school or computing center library, and the IDSM can also be Hpurchased. Additional technical details of the Alpha microprocessor are Havailable in the Alpha Architecture Reference Manual documentation that Fis available for download. (Pointers to Alpha technical documentation Tare available in Section 14.6, and elsewhere.)

EFor higher-level (less technical) details, the OpenVMS documentation Hset is available on-line. The Programming Concepts and the File Systems Emanual are probably the best manuals to start with, depending on the 1particular level of detail the research requires.

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

2.17 Basic Units of Measurement?



EOpenVMS and the underlying hardware use various units of measurement Ffor disk and memory storage, and related abbreviations also typically Eexist. This section covers the most common units, and the associated abbreviations.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.

CUnder OpenVMS VAX and OpenVMS Alpha, the disk volume block size is 1consistent, with each block containing 512 bytes.

EThe 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 a Hcombination of the total number blocks on the disk volume and the total Gsize of the volume storage bitmap. The allocation granularity is known Cas the volume cluster factor---the cluster factor is the number of Gblocks in a disk cluster, and it is the smallest number of blocks that -can be allocated on a particular disk volume.

BPrior to OpenVMS V7.2, the maximum permissible size of the bitmap Hrequires larger cluster factors as volume sizes increase. Starting with DV7.2, the bitmap can be larger, and cluster factors as small as one block can be used.

CThe number of bytes in a file can be determined by multiplying the Gnumber of blocks allocated for the file times the number of bytes in a Dblock. 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 block Fallocations are not permitted. For other file formats, the EOF marker is not meaningful.

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

BOpenVMS assumes that the device driver and the underlying storage Fdevice will present the file system with addressable units of storage Eof 512 bytes in size, or the appearance of same. Various third-party FCD-ROM devices, for instance, support only 2048 byte blocks, and such Bdevices are incompatible with the standard OpenVMS device drivers.

CTo determine the number of bytes required for a file from DCL, one Hoption uses the f$file_attributes item EOF, multiplied by the size of a Hblock 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 to 0differentiate sequential files from other files.I

2.17.2 How many bytes are in a memory page?



HA memory page is the minimum unit of memory allocation in OpenVMS. With EOpenVMS VAX, the memory page size matches the disk block size: it is always 512 bytes.

GWith OpenVMS Alpha, the memory page size is variable, and it can range Efrom 8192 bytes (8 kilobytes) up to 64 kilobytes. The current system Gpage size can be determined using the sys$getsyi or f$getsyi PAGE_SIZE Eitem. Programs with hardcoded constants for the memory page size (or Apage alignment) should always assume a page size of 64 kilobytes.

DOn OpenVMS I64, the memory page size is also variable, ranging from H4096 bytes (4 kilobytes) up to 256 megabytes (MB) and potentially up to E4 gigabytes (GB). As with OpenVMS Alpha, sys$getsyi and f$getsyi and Gthe PAGE_SIZE itemcode can and should be used to determine the current Dsystem page size. In general, OpenVMS I64 will use a page size of 8 kilobytes, or larger.

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

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



EThe smallest granularity of disk storage addressing is called a disk Eblock, or sometimes a disk sector. Groups of disk blocks are usually Aorganized together into the smallest unit of storage that can be Hallocated, and this unit is called a disk cluster. The number of blocks Ein a cluster is the cluster factor, and is established when the disk volume is initialized.

DEach individual disk block is composed of five hundred twelve (512) Ebytes, or one-half kilobyte. Each byte is comprised of eight bits. A Fbit represents the smallest unit of information, typically refered to as a one or a zero.

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

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

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

 

"
6          Base Ten                           Base Two G          --------------------------------   ------------------------- GKilobyte  (KB)  10**3                 1000   2**10                1024 GMegabyte  (MB)  10**6              1000000   2**20             1048576 GGigabyte  (GB)  10**9           1000000000   2**30          1073741824 GTerabyte  (TB)  10**12       1000000000000   2**40       1099511627776 GPetabyte  (PB)  10**15    1000000000000000   2**50    1125899906842624 GExabyte   (EB)  10**18 1000000000000000000   2**60 1152921504606846976 




GThe base ten representation of the 2**40 value is 1099511627776, which Fis obviously rather ugly. When viewed as a base eight or base sixteen D(octal or hexadecimal, respectively) value, the value is far nicer. HSpecifically, the value is 10000000000 and 40000000 when represented in $octal and hexadecimal, respectively.



/4  
FAQ 6 Notation

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


HOpenVMS operating system references to system and storage are generally @to the base-two version (eg: 1024, in the case of a kilobyte or Gkilobit) while storage hardware references and hardware specifications 1are generally to the base-ten version (eg: 1000).

ATo convert OpenVMS disk blocks to (base two) kilobytes (KB; 1024 >bytes), simply divide by two. To convert blocks to (base two) Gmegabytes, divide by 2048. Blocks to (base two) gigabytes (GB), divide Cby 2097152. These particular divisions can also be performed using Fbitshifts: to divide a value by two, shift the binary value rightward by one bit position.

BTo convert OpenVMS disk blocks to (base ten) kilobytes, divide by approximately 1.953125.

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


C

Chapter 3
Documentation


A

If you are searching for something here, please (consider using the text-format FAQ.

l

3.1 Where can I find online copies of OpenVMS manuals?



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

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



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

FMGBOOK, a viewer for Bookreader-format documentation is available for Ccharacter-cell terminals (eg. VTxxx) via the WKU VMS Freeware file Tserver -- see question Section 13.1 for details.

GInformation on the XPDF DECwindows PDF viewer for OpenVMS is available ein Section 13.1, and XPDF kits are available on various Freeware Gdistributions. An alternative on OpenVMS Alpha uses the Adobe Java PDF Eviewer, though this viewer is generally considered to be both slower =and more resource-intensive when compared to the XPDF viewer.m

3.2 What online information and websites are available?



AOn your OpenVMS system, the HELP command can provide a wealth of Cinformation, not only on DCL commands but on system services (HELP HSystem_Services) and Run-Time Library routines (HELP RTL_Routines). The >introduction displayed when you type the HELP command with no .additional keywords provides further pointers.

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

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

[   "                                                                                                                                                                                                                                       
Table 3-1 OpenVMS Websites
URL Sponsor
 HP OpenVMS Marketing
  L http://www.hp.com/go/openvms/
 Encompass DFWCUG
  1 % http://www.openvmshobbyist.org/
 Arne Vajhøj
  J http://www.levitte.org/~ava/
 Saiga Systems
  < http://www.saiga.com/
 Wayne Sewell
  D http://www.tachysoft.com/
 proGIS Software
  2 & http://www.progis.de/openvms.htm
 Jeff Cameron
  J http://www.jcameron.com/vms/
> David Mathog's (quite useful) information about OpenVMS.
  : . http://saf.bio.caltech.edu/soft_doc.html
 Cracking
 "The Beave"K
Includes system cracking information that can be of interest to M OpenVMS System Managers, and to OpenVMS Network and Security Managers. < This information is available at the Deathrow cluster.
  @ 4 http://manson.vistech.net/ht_root/Hack-VMS-faq
, Undocumented Features
 DECUS Deutschland
  F : http://zinser.no-ip.info/www/eng/vms/qaa/undoc.htmlx
 Arne Vajhøj
  ; / http://www.levitte.org/~ava/vms_tip.htmlx
N The OpenVMS Freeware contains various examples of undocumented features  and interfaces
  8 , http://www.hp.com/go/openvms/freeware/
C Comparisons of UNIX and Linux shell commands and DCL Commands
  E 9 http://www.mcsr.olemiss.edu/unixhelp/VMStoUNIX.html
  J > http://wwwvms.mppmu.mpg.de/vmsdoc/UNIX_VMS_CMD_XREF.HTML
; Comparisons of emacs and OpenVMS text editor commands
  D http://www.unh.edu/cis/docs/vms-to-unix/Emacs/cheat-sheet.html
% Bibliographies
  = 1 http://www.openvms.org/pages.php?page=Books
  < 0 http://www.levitte.org/~ava/vms_book.htmlx
# Introductory
  r Please see Table 3-2 for listings of introductory web sites and  related materials.
" Programming
An OpenVMS Programming FAQ
  F http://www.pdv-systeme.de/users/martinv/VMS_Programming_FAQ.html
! Networking
J Tutorial information and tips for connecting OpenVMS systems to the  Internet
  1 % http://www.tmesis.com/internet/
C Documentation and Specifications for DECnet Phase IV, DECnet 6 task-to-task DCL examples, and a whole lot more.
  6 * http://www.hp.com/go/openvms/wizard/
/ HP OpenVMS Documentation
  s Please see Table 3-2 for listings of documentation web sites and  related materials.
) System Performance
  < See Section 14.2.
' Patch (ECO) Kits
  I For the HP Services FTP server hosting Various contract-access and j non-contract access ECO (patch) kits, see section Section 5.17.
+ Catalogs and Pricing
3 HP Product QuickSpecs and product information
  7 + http://www.hp.com/go/productbulletin/
6 The HP Systems and Options Catalog (SOC) archive
  http://www.compaq.com/products/4
quickspecs/soc_archives/SOC_Archives.html
5 Hardware and Software Archives
A The VAXarchive, including hardware and software information
  6 * http://vax.sevensages.org/index.html
" A VAX to Alpha upgrade diary
  H < http://www3.sympatico.ca/n.rieck/docs/alpha_diary.html
9 Scanned versions of old DIGITAL manuals from DFWCUG
  < 0 http://www.montagar.com/~patj/dec/hcps.htm
B A wide variety of HP VAX, Alpha, platform and other product 7 documentation. Some introductory, some technical.
  G ; http://www.compaq.com/support/techpubs/qrg/index.html
! dtrwiz's Datatrieve website
  N http://dtrwiz.home.netcom.com/





 r Y \ ^  
PreviousNextContentsIndex