=;The OpenVMS Frequently Asked Questions (FAQ)D

The OpenVMS Frequently Asked Questions (FAQ)



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9.6 What is the maximum file size, and the RMS record size limit?



ERMS can store individual files of a size up to the maximum supported Gvolume size. Under OpenVMS V6.0 and later, the volume size and the RMS Cmaximum file size limit is 2**31 * 512 bytes---one terabyte (1 TB).

C"Use a volume set to provide a large, homogeneous public file Hspace. You must use a volume set to create files that are larger than a Fsingle physical disk volume. (The file system attempts to balance the Cload on the volume sets, for example, by creating new files on the 1volume that is the least full at the time.)"

E"You can add volumes to an existing volume set at any time. The 7maximum number of volumes in a volume set is 255."EFurther, with a 255 member bound-volume set, the theoretical maximum @limit of files is 4,261,478,145 files, less the directories and reserved files.

EThe RMS formats---sequential, relative, and indexed---are limited by Ethe one terabyte maximum volume size. RMS relative files are further Dlimited to a number of records that will fit in 32 bits---4 billion Crecords. Sequential and indexed formats do not have a record limit.

qAlso see Section 2.17.1, Section 14.25.p

9.7 How do I write CD-Recordable or DVD media on OpenVMS?



DHow to create CD-R, CD-RW, DVD-R, DVD+R, DVD-RW, or DVD+RW media on OpenVMS?

FFor information on CD and DVD optical media drives on OpenVMS, please osee Section 14.29. For information on the creation of OpenVMS media and Fof OpenVMS bootable media, a full step-by-step sequence is documented Fin the OpenVMS Ask The Wizard topic (9820). An abbreviated version of the sequence is included here.

HRecording (writing) of CD and DVD optical media requires a recording or =media mastering application or tool, and both commercial and Fnon-commercial options are available. For OpenVMS V8.3 and later, see the COPY/RECORDABLE_MEDIACcommand available within OpenVMS itself. Alternatively, please see HCDRECORD (both non-DVD and DVD versions are available, and at least one Hcommercial version is available), and also see DVDwrite (commercial) or BDVDRECORD (open source). A port of CDRECORD is present in OpenVMS V7.3-1 and later.



FAlternatively, consider the following command on OpenVMS Alpha V7.3-1 and later:

 

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@SYS$MANAGER:CDRECORD.COM HELP 




EWhile folks have had success getting PC-based CD-R/RW or DVD-R/RW or EDVD+R/RW tools to work with OpenVMS partitions, it is far easier and Cmore reliable to use the OpenVMS-based versions of these tools and Edirectly-attached devices. If you use a Windows-based tool, you will Dwant to specifically select its raw mode, image mode, or block-copy Cmode, depending on the terminology within the particular tool. The Gtransfer mode and selections is variously refered to as a disk-at-once E(DAO) 2048-byte block ISO Mode 1 raw/image/block data disk recording mode.

FMore details: Creation of CD recordable or DVD recordable media under AOpenVMS typically involves one of two approaches: the use of the optional CD-R (`Scribe')Gcapabilities available for the InfoServer or other "offline" Ghardware packages (PC-based packages will be included in this), or the 4use of a host-based package such as the CDRECORD or ECOPY/RECORDABLE_MEDIA (V8.3 and later) or other utilities, including @OpenVMS ports of common open-source tools made available by Dr. DEberhard Heuser-Hofmann and various others. Commercial packages and options are also available.Dr. Heuser-Hofmann has DVDwrite=, a commercial package which can record DVD media. ( 

HOpenVMS can read ODS-2, ODS-5, and ISO-9660 format CD-ROMs and DVD-ROMs directly.D(If you are very careful, you can create a dual-format CD-R; a CD-R Awith both ODS-2 and ISO-9660 or both ODS-5 and ISO-9660 or both.)

EOpenVMS does not support ISO-9660:1999, nor the Joliet or Rock Ridge Eextensions to ISO-9660, nor can OpenVMS decrypt copy-protected video DVDs.

InfoServerB hardware configurations are no longer available from HP, but may A potentially be acquired through other means; as used equipment. A InfoServer support also has very specific CD-R recording device D prerequisites, and these recording devices are no longer generally available.

EPackages related to the use of DVD archiving are also available, see Athe multi-volume capabilities of the DVDarchive/restore Freeware.

 

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JF http://www.geocities.com/SiliconValley/Lakes/9999/vmscdwri.html  




;Additional information is available at the following sites:



U.S. DesignF offers a package that includes the tools necessary to create a CD or ; DVD-R with either ISO-9660 or ODS-2 format, for standaloneACD-R/RW, DVD-R, or DVD+R/RW drives, for recent OpenVMS versions. Details are available at:



lAlso see Section 9.7.2 for details on access to recorded media on older CD-ROM drives.H

9.7.1 CD and DVD notation, terminology?



CCD-ROM is pre-recorded Compact Disk media, and is the original and Boldest CD format. The original CD media was physically stamped, a Erecording process that is now largely reserved to the highest-volume media reproduction requirements.

GCD-R is CD Recordable, a write-once storage medium that can be read by Fall but the oldest of CD drives; a format which can be read and often #even recorded by most CD-RW drives.

ECD-RW is CD ReWritable, a format which is readable by many CD drives Aand by most CD-R drives, and with media that can be recorded and re-recorded by CD-RW drives.

GCD media recording speeds are listed as multiples of 150 kilobytes per Esecond, so a 10X drive records at 1500 kilobytes (1.5 megabytes) per >second. 600 MB (70 minutes) and 700 MB (80 minutes) recording Acapacities are both widely available. The minutes designation is Dderived from the traditional audio-format recording capacity of the particular media.

:DVD-R/RW is the older of two common Digital Versatile DiskGrecording formats, and the DVD-R Recordable or DVD-RW ReWritable media Acan be read by many DVD drives. As with CD-R formats in older CD Ddrives, older DVD and particularly first-generation DVD players may (have problems reading this media format.

?DVD+R/RW is the newer of the two common Digital Versatile Disk Grecording formats, and the DVD+R Recordable or DVD+RW ReWritable media Bcan be read by many DVD drives. Akin to DVD-R/RW media, older and Hparticularly first-generation DVD drives can have problems reading this media format.

FThe DVD Plus-series drives and media tend to record faster than Minus Fdrives, as (as of this writing) the Plus (+) drives do not require an Einitial media formatting pass and the Minus (-) drives do. While the Gappropriate Plus (+) or Minus (-) DVD raw media must be chosen for the Fparticular DVD recorder (and DVD recording drives that are compatible Hwith and capable of using both Plus and Minus media are available), the Hresulting recorded media is generally readable (playable) in all recent GDVD drives and DVD players, regardless of type. (Compatibility is best Bwithin the same media-series devices of course, but be certain to Hverify compatibility across devices regardless of the particular device &or particular recording media chosen.)

HPresently Plus (+) media is slightly more expensive than Minus (-), but Gwith the prices of all CD and all DVD media continuing to consistently Efall, the differences in DVD media costs are becoming irrelevent for 4all but the production of huge volumes of DVD media.

FThe rated DVD recording speeds are in multiples of 1353 kilobytes per Fsecond, thus a DVD 1X drive is roughly equivalent to a CD 9X drive in $I/O requirements and transfer speed.

FDVD drive recording speed can and does vary. DVD disk drive recording Hspeed is limited by the rated recording speed of the media used, so the Eslower (and cheaper) DVD media will not record any more quickly in a Ffaster drive. A 2.4X DVD drive loaded with 1X media will record at 1X.[

9.7.2 Use of RRD42 and other older (embossed-media) CD drives?



The RRD42H series SCSI CD-ROM drive is sufficiently old that it can have problems D processing CD-R and CD-RW media. Other very old CD drives can have H equivalent media compatibility problems when attempting to read (much) G newer CD media and newer CD media technologies. These older CD drives 2 are generally intended for use with the so-calledE embossed media, rather than with non-embossed recorded (recordable) ! media now in common circulation.

FPlease consider using a slightly-less-ancient CD-ROM or CD-R or CD-RW 7drive when working with non-embossed recorded CD media.

HTo paraphrase one knowledgable---though deliberately nameless---storage @engineer, "The RRD42 drive is just past the drooling idiot stage".d

9.7.3 Creating Bootable OpenVMS I64 CD or DVD Media? SYS$SETBOOT?



DIf you are creating a bootable CD or DVD media for use with OpenVMS FI64, you will want to specify the SYS$SETBOOT block size of 2048, and Hyou will also want a disk cluster factor that is a multiple of four via DINITIALIZE/CLUSTER=4 (or 8, or...), or you will want to ensure that #SYS$EFI.SYS and SYS$DIAGNOSTICS.SYSHare aligned to a multiple of four blocks; to a 2048 byte boundary. This Halignment and this blocking is only necessary for OpenVMS I64, and only 7when creating optical media OpenVMS I64 for bootstraps.

FThe default 512-byte block setting used by SYS$SETBOOT is the correct Band expected value for traditional disk bootstraps on OpenVMS I64 systems.

COnce the boot files are loaded, OpenVMS I64 operates with 512-byte >blocks; as is the case with ATAPI disks on OpenVMS Alpha, all Capplication code will only see 512-byte blocks on optical media on OpenVMS I64.

=OpenVMS I64 V8.2 and later are expected to have a version of GSYS$SETBOOT that will flag a misaligned SYS$EFI.SYS and (if present) a $misaligned SYS$DIAGNOSTICS.SYS file.

EFor information on SYS$SETBOOT and the SET BOOTBLOCK command, please psee Section 14.3.9 and see the OpenVMS documentation. The purpose and Eintent of the SYS$SETBOOT.EXE image and the SET BOOTBLOCK command is Aanalogous to the WRITEBOOT.EXE image on existing OpenVMS VAX and OpenVMS Alpha systems.

FFor information on CD and DVD optical media drives on OpenVMS, please isee Section 14.29. For additional related information on creating ?bootable OpenVMS media, please see Ask The Wizard topic (9820).j

9.8 What I/O transfer size limits exist in OpenVMS?



HThe maximum transfer size is an attribute of the particular I/O device, Fcontroller and driver combination; there is no inherent limit imposed Fby OpenVMS (other than the fact that, today, byte counts and LBNs are generally limited to 32 bits).

DThe maximum size of a device I/O request is limited by the value in BUCB$L_MAXBCNT, which is set by the device driver based on various Dfactors. (Also check the setting of the MAXBUF system parameter for 6buffered I/O transfers, and check the process quotas.)

ECurrently, SCSI drivers limit I/O transfers to FE00(16) bytes, 65024 Cbytes (decimal). The reasons for this transfer size limitation are Dlargely historical. Similarly, DSSI devices are limited to the same Dvalue, this for hardware-specific reasons. Transfers to HSC and HSJ Edevice controllers via the CI are limited to 1,048,576 bytes. Client EMSCP-served devices are limited to 65535 bytes---to help ensure that Fthe I/O fragmentation processing happens on the client and not on the server system.

DParts of the OpenVMS I/O subsystem are optimized for data transfers <less than 64KB, because (obviously) most I/O operations are H(substantially) less than that. OpenVMS can handle larger transfers, if (the driver and the device can handle it.

jAlso see Section 9.4, Section 9.5.o

9.9 Can I use ODBC to connect to OpenVMS database files?



DYes, you can use various available third-party packages that permit ?remote ODBC clients to access RMS files and various commercial databases via the network.

?For RMS, consider acquiring one of the packages available from EEasySoft, Attunity Connect (formerly known as ISG Navigator), Oracle D(DB Integrator), SolutionsIQ, OpenLink Software (OpenLink Universal Data Access), and Synergex.

The unixODBC9 package available at http://www.unixodbc.org 8has variously been found to operate on OpenVMS, as well.

GFor specific commercial databases (other than RMS, of course), contact ,the database vendor directly for assistance.w

9.10 If my disks are shown as VIOC Compatible, am I using XFC?



Yes, you are using XFC caching.

DDisks that are using XFC caching use communication and coordination :protocols that are compatible with the older VIOC caching Gimplementation. With the initial implementation of XFC on OpenVMS, you Gcan use the command SHOW MEMORY/CACHE to see no disks reported in full XFC mode;Call disks shown will be listed in "VIOC Compatable Mode".

DIf you have the OpenVMS system parameter VCC_FLAGS set to 2 and are Eusing OpenVMS Alpha V7.3-1 or later, or are using OpenVMS Alpha V7.3 Fwith the VMS73_XFC V2.0 ECO kit or later or with the UPDATE kits, you are using XFC.

FAnother confusion: the XFC product version is and remains V1.0 in all Hreleased configurations, please do not confuse the internal XFC product @version (displayed by various commands) with the version number Aassociated with the various ECO kit(s). XFC V1.0 does not permit Evolumes to enter full XFC caching, as displayed by the "Vols in Full XFC mode"5 portion of the DCL command SHOW MEMORY/CACHE output.o

9.11 RMS Sequential Files and Platform Portability?



DWhen working with mixed platforms, you will want to become familiar Hwith the various RMS sequential record formats, including Variable with CFixed Control (VFC), stream, stream LF, and stream CR, among other record formats.

FSwitching formats uses CONVERT/FDL or SET FILE/ATTRIBUTES. The former Cconverts files, the latter resets attributes. Text editors tend to Cselect attributes when creating new files that may or may not meet Hrequirements. If the default attributes do not match your requirements, Fcreate a stub file, SET FILE/ATTR, then edit the existing file. (Most 6editors will preserve attributes on an existing file.)

AWhen working with Windows, stream is usually the best choice for Fsequential file operations. Stream LF is most commonly used with UNIX Eand C applications. Windows and UNIX tend not to be able to directly 9read files of "unexpected" sequential RMS record formats.

DVFC is a common OpenVMS format, encoding the record length into the Frecord. It is this extra data that can cause corruption-like problems Bwhen viewed without RMS; either directly via $qio or via the file Fsystem API on other operating system platforms. You will want to look Bat the low-level record formats, and at the RMS and the Files and 2Applications documentation in the OpenVMS manuals.

HIf transfering through other platforms, use of a current version of Zip F(with the "-Vv" or "-V" option) and unzip, or use of a BACKUP saveset Cwill contain and maintain the RMS file and record attributes. (For FBACKUP and its own attributes requirements, see the restoration tool.)Z

9.12 How to read locked files?



FFiles can be locked by applications, and various approaches including CCONVERT/SHARE and DUMP/ALLOCATED can be used, as can the following command sequence:

 

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)$ open/read/share=write x lockedfile.txt 	$ type x 




HIf you can rebuild the application from source, details related to file Bsharing are in Section 10.17.




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