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G OpenVMS doesn't have an "undelete" function. However, if you H are quick to write-protect the disk or if you can guarantee that no new H files get created or existing files extended, your data is still on the G disk and it may be possible to retrieve it. The FLORIAN tool available E from various websites can potentially recover the file, see question g Section 13.1 for pointers. Other alternatives here include the DFU < tool, available on the OpenVMS Freeware CD-ROM distribution.
H If you are setting up a user environment for yourself or for others, it B is quite easy to use DCL to intercept the DELETE command, using a symbol:
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" & $ DEL*ETE :== @SYS$LOGIN:MYDELETE.COM |
F The DELETE symbol will cause the procedure to be invoked whenever the A user enters the DELETE command, and it can copy the file(s) to a D "trashcan" subdirectory before issuing a "real" H DELETE on the files. Other procedures can retrieve the file(s) from the F "trashcan" subdirectory, and can (and should) clean out the F "trashcan" as appropriate. (Realize that this DELETE symbol A can interfere with DELETE/GLOBAL and other similar DCL commands.) u 9.2 Why does SHOW QUOTA give a different answer than DIR/SIZE?
H DIRECTORY/SIZE doesn't take into account the size of file headers which H are charged to your quota. Also, unless you use DIRECTORY/SIZE:ALL, you G will see only the "used" size of the file, not the allocated G size which is what gets charged against your quota. Also, you may have files in other directories.
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" ) $ DIRECTORY/SIZE=ALL/GRAND [username...] 7 Grand total of D1 directories, F1 files, B1/B2 blocks. + $ DIRECTORY/SIZZ=ALL/GRAND [-]username.DIR 2 Grand total of 1 directory, 1 file, B3/B4 blocks. $ SHOW QUOTA 1 User [username] has B5 blocks used, B6 available > of B7 authorized and permitted overdraft of B8 blocks on disk |
G If the user has no files in other directories and all file-headers are . only 1 block, then the following should apply:
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" B5=B2+B4+F1+1 |
> If the diskquota has drifted out of synchronization, then the G system-manager can force a quota rebuild---due to various factors, the F quota file can potentially drift from the actual use over time, and a ; periodic rebuild can be performed at appropriate intervals.
G Also be aware that the DIRECTORY/SIZE command can report larger values D than might otherwise be expected when used to evaluate files and/or G directories that are alias links---such as the system roots on OpenVMS F system disks---as the command reports a total that is cumulative over D all of the files and directories examined, without regard for which B ones might be alias entries and which are not. (In other words, a C DIRECTORY/SIZE of an entire OpenVMS system disk will report a disk G useage value larger than the (usually more accurate) value reported by G the SHOW DEVICE command. This as a result of the alias entries linking > each SYS$SYSDEVICE:[SYSCOMMON]SYS*.DIR directory file and the 4 SYS$SYSDEVICE:[000000]VMS$COMMON.DIR file together.) u 9.3 How do I make sure that my data is safely written to disk?
F If your application must absolutely guarantee that data is available, D no matter what, there's really no substitute for RMS Journaling and E host- or controller-based shadowing. However, you can achieve a good G degree of data integrity by issuing a SYS$FLUSH RMS call at appropriate C times (if you're using RMS, that is.) If you're using a high-level E language's I/O system, check that language's documentation to see if F you can access the RMS control blocks for the open file. In C you can use fflush followed by fsync.
@ For details on disk bad block handling on MSCP and on SCSI disk 6 devices, please see Ask The Wizard (ATW) topic (6926).
H For additional information on the OpenVMS Ask The Wizard (ATW) area and B for a pointer to the available ATW Wizard.zip archive, please see 0 Section 3.9. v 9.4 What are the limits on file specifications and directories?
H A file specification has an aggregate maximum size of 255 characters at G present. The node and device specification may be up to 255 characters F each - file name and file types may be up to 39 characters each. File A versions are from 1 through 32767, though 0 (latest version), -0 D (oldest version) and -n (n'th previous version) can be used in most H contexts. A file specification may not have more than 8 directories and B subdirectories - while it is possible to create subdirectories of D greater depth, accessing them is problematic in most cases and this should be avoided.
H Application developers should use OpenVMS-supplied routines for parsing E file specifications - this ensures that changes in what is allowable H will not tend to break your application. Consider that various parts of G the file specification may contain quoted strings with embedded spaces C and other punctuation! Some routines of interest are SYS$FILESCAN, B SYS$PARSE and LIB$TRIM_FILESPEC. For further information, see the # OpenVMS Guide to File Applications.
F Performance of larger directory files improves (greatly) with OpenVMS H V7.2 and later---operations on directory files of 128 blocks and larger G were rather slower on earlier OpenVMS releases due to the smaller size E of the directory cache and due to the directory I/O processing logic.
F For fastest directory deletions, consider a reverse deletion---delete G from the last file in the directory to the first. This reversal speeds H the deletion operation by avoiding unnecessary directory I/O operations E as the files are deleted. Tools such as the Freeware DFU can be used for this purpose, ? as can various available reverse-DELETE DCL command procedures. s 9.5 What is the largest disk volume size OpenVMS can access?
G One Terabyte (TB; 2**31 blocks of 2**9 bytes; 0x07FFFFFFF blocks). 255 H volumes in a volume set. The largest contiguous allocation possible for * any particular file is 0x03FFFFFFF blocks.
E Prior to the release of V6.0, the OpenVMS file system was limited to @ disk volumes of 8.38 GB (2**24 blocks, 16777216 blocks) or less.
D On some systems, there are restrictions in the console program that H limit the size of the OpenVMS system disk. Note that data disks are not D affected by console program limits. For example, all members of the VAXstation 3100 C series are limited to a system disk to 1.073 GB or less due to the F console, though larger data disks are possible. This limit due to the H SCSI drivers used by and built into the console ROM to read the OpenVMS D bootstrap files, and these same drivers are also used by OpenVMS to write the system crashdump.
> There are numerous discussions of this VAXstation 3100 in the F comp.os.vms newsgroup archives. Please use Google newsgroup search to @ search the archives for further details, for discussions of the B workarounds, and for details of the potential for a simple failed G bootstrap and particularly for discussions of the potential for severe # system disk corruptions on crashes.
E Some SCSI disks with capacities larger than 8.58 gigabytes (GB) will G require the use of an OpenVMS ECO kit (eg: ALPSCSI04_062 or later; see l Section 14.26 for details) for new SCSI device drivers. Failure to use = this ECO can cause "rounding errors" on the SCSI disk device E capacity---OpenVMS will not use nor display the full capacity of the C drive---and "%sysinit-e-error mounting system device status equals G 000008C4" (8C4 -> "%SYSTEM-?-FILESTRUCT, unsupported file structure H level") errors during bootstrap. (One workaround for the bootstrap when 6 the bitmap is located far into the disk is the use of G INIT/INDEX=BEGIN.) The problem here involves the particular extensions : and fields used for larger capacity disks within the SCSI = specifications and within the various intepretations of same.
For ATA (IDE) disk drives:
g See Section 14.4.4.2 for additional ATA SYS$DQDRIVER information.
C Be aware that a known restriction in certain older versions of the E Alpha SRM Console prevents booting most ATA (IDE) drives larger than F 8.455 GB, depending on exactly where the various files are located on D the volume. Updated SRM consoles for systems with SRM and ATA (IDE) @ drive support are (will be) available. (OpenVMS Engineering has E successfully bootstrapped 20GB ATA (IDE) disks using the appropriate SRM console version.)
E All disk-related listed in this section are stated in units of "disk G (base ten) gigabytes" (1 GB = 10^9 bytes) and not in units of B "software (base two) gigabytes" (1 GB = 2^30; 1 GB = 1073741824.) l bytes. Please see Section 14.26 for details of the nomenclature and of the units. |
C Be aware that larger disks that are using an extension of SCSI-2--- F disks that are using a mode page field that the SCSI-2 specifications D normally reserved for tape devices---to permit a larger disk volume G size will require a SCSI driver update for OpenVMS, and this change is D part of V7.1-2 and later, and also part of ALPSCSI07_062 and later. F (These larger disks disks will typically report a DRVERR, or will see H the volume size "rounded down".) SCSI disks larger than 16777216 blocks F cira 8.455 GB (base ten); 8GB (base two) require this ECO, or require ) the use of OpenVMS Alpha V7.1-2 or later.
H Applications written in C can be limited to file sizes of two gigabytes B and less, as a result of the use of longword values within C file B operations, and specifically off_t. This restriction is lifted in E OpenVMS V7.3-1 and later, and with the application of the C ECO kits C available for specific earlier releases. The use of a longword for E off_t restricts applications using native C I/O to file sizes of two D gigabytes or less, or these applications must use native RMS or XQP calls for specific operations.
n Also see Section 14.14, Section 14.26. x 9.6 What is the maximum file size, and the RMS record size limit?
E RMS can store individual files of a size up to the maximum supported G volume size. Under OpenVMS V6.0 and later, the volume size and the RMS C maximum file size limit is 2**31 * 512 bytes---one terabyte (1 TB).
C "Use a volume set to provide a large, homogeneous public file H space. You must use a volume set to create files that are larger than a F single physical disk volume. (The file system attempts to balance the C load on the volume sets, for example, by creating new files on the 1 volume that is the least full at the time.)"
E "You can add volumes to an existing volume set at any time. The 7 maximum number of volumes in a volume set is 255."
E The RMS formats---sequential, relative, and indexed---are limited by E the one terabyte maximum volume size. RMS relative files are further D limited to a number of records that will fit in 32 bits---4 billion C records. Sequential and indexed formats do not have a record limit.
q Also see Section 2.17.1, Section 14.26. p 9.7 How do I write CD-Recordable or DVD media on OpenVMS?
D How to create CD-R, CD-RW, DVD-R, DVD+R, DVD-RW, or DVD+RW media on OpenVMS?
F Alternatively, consider the following command on OpenVMS Alpha V7.3-1 and later:
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" @SYS$MANAGER:CDRECORD.COM HELP |
E While folks have had success getting PC-based CD-R/RW or DVD-R/RW or E DVD+R/RW tools to work with OpenVMS partitions, it is far easier and C more reliable to use the OpenVMS-based versions of these tools and E directly-attached devices. If you use a Windows-based tool, you will D want to specifically select its raw mode, image mode, or block-copy C mode, depending on the terminology within the particular tool. The G transfer 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.
F More details: Creation of CD recordable or DVD recordable media under A OpenVMS typically involves one of two approaches: the use of the optional CD-R (`Scribe') F capabilities available for the InfoServer or other "offline" hardware G packages (PC-based packages will be included in this), or the use of a B host-based package such as the CDRECORD or CDWRITE13_VMS or other D utilities, including OpenVMS ports of common open-source tools made H available by Dr. Eberhard 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. (
; OpenVMS can read ODS-2, ODS-5, and ISO-9660 format CD-ROMs. D (If you are very careful, you can create a dual-format CD-R; a CD-R A with both ODS-2 and ISO-9660 or both ODS-5 and ISO-9660 or both.)
InfoServer B 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.
E Packages related to the use of DVD archiving are also available, see A the multi-volume capabilities of the DVDarchive/restore Freeware.
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" J F http://www.geocities.com/SiliconValley/Lakes/9999/vmscdwri.html |
; Additional information is available at the following sites:
U.S. Design F offers a package that includes the tools necessary to create a CD or ; DVD-R with either ISO-9660 or ODS-2 format, for standalone A CD-R/RW, DVD-R, or DVD+R/RW drives, for recent OpenVMS versions. Details are available at:
l Also 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?
C CD-ROM is pre-recorded Compact Disk media, and is the original and B oldest CD format. The original CD media was physically stamped, a E recording process that is now largely reserved to the highest-volume media reproduction requirements.
G CD-R is CD Recordable, a write-once storage medium that can be read by F all but the oldest of CD drives; a format which can be read and often # even recorded by most CD-RW drives.
E CD-RW is CD ReWritable, a format which is readable by many CD drives A and by most CD-R drives, and with media that can be recorded and re-recorded by CD-RW drives.
G CD media recording speeds are listed as multiples of 150 kilobytes per E second, so a 10X drive records at 1500 kilobytes (1.5 megabytes) per > second. 600 MB (70 minutes) and 700 MB (80 minutes) recording A capacities are both widely available. The minutes designation is D derived from the traditional audio-format recording capacity of the particular media.
: DVD-R/RW is the older of two common Digital Versatile Disk G recording formats, and the DVD-R Recordable or DVD-RW ReWritable media A can be read by many DVD drives. As with CD-R formats in older CD D drives, 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 G recording formats, and the DVD+R Recordable or DVD+RW ReWritable media B can be read by many DVD drives. Akin to DVD-R/RW media, older and H particularly first-generation DVD drives can have problems reading this media format.
F The DVD Plus-series drives and media tend to record faster than Minus F drives, as (as of this writing) the Plus (+) drives do not require an E initial media formatting pass and the Minus (-) drives do. While the G appropriate Plus (+) or Minus (-) DVD raw media must be chosen for the F particular DVD recorder (and DVD recording drives that are compatible H with and capable of using both Plus and Minus media are available), the H resulting recorded media is generally readable (playable) in all recent G DVD drives and DVD players, regardless of type. (Compatibility is best B within the same media-series devices of course, but be certain to H verify compatibility across devices regardless of the particular device & or particular recording media chosen.)
H Presently Plus (+) media is slightly more expensive than Minus (-), but G with the prices of all CD and all DVD media continuing to consistently E fall, the differences in DVD media costs are becoming irrelevent for 4 all but the production of huge volumes of DVD media.
F The rated DVD recording speeds are in multiples of 1353 kilobytes per F second, thus a DVD 1X drive is roughly equivalent to a CD 9X drive in $ I/O requirements and transfer speed.
F DVD drive recording speed can and does vary. DVD disk drive recording H speed is limited by the rated recording speed of the media used, so the E slower (and cheaper) DVD media will not record any more quickly in a F faster 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 RRD42 H 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-called E embossed media, rather than with non-embossed recorded (recordable) ! media now in common circulation.
F Please consider using a slightly-less-ancient CD-ROM or CD-R or CD-RW 7 drive when working with non-embossed recorded CD media.
H To paraphrase one knowledgable---though deliberately nameless---storage @ engineer, "The RRD42 drive is just past the drooling idiot stage".
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