A set of contiguous clusters is known as an extent. The size of an extent varies according to the number of contiguous clusters. For example, assume a file requires 1000 blocks of storage, and the file system finds a set of 800 contiguous blocks and a set of 200 contiguous blocks. The file would then be stored in two extents: one consisting of 800 blocks, the other of 200.
The primary header of a file points to the first extent of that file and to as many extents as can be stored in the map area of the primary header. When the number of extents required to contain a file exceeds the map area available in the primary header, or the ACL is too large to fit in the primary header, the file is allocated an extension header. Extension headers contain all the constant data of the primary header, as well as the variable data (in the header map area and access control list) that specifies the locations of the extents to which the extension header points.
ANALYZE/DISK_STRUCTURE confirms the validity of a file by working its way down the list of primary and extension headers of the file. During this process, ANALYZE/DISK_STRUCTURE checks the validity of the file header, the chain of pointers to all extension headers, the retrieval pointers in all headers, and the attributes of the file.
The storage bit map file is a contiguous file that the file system uses to keep track of the available space on a volume. This file contains a storage control block (SCB), which consists of summary information intended to optimize the Files--11 space allocation, and the bit map itself, which lists the availability of individual blocks.
The SCB contains summary information about the volume (cluster factor, volume size, blocking factor, and so forth). Each bit in the bitmap represents an allocatable cluster on the volume. If a bit is set, the corresponding cluster is available for use. If a bit is clear, the cluster is not available.
During normal operation, the operating system moves portions of the bitmap in and out of cache memory. The state of each bit in memory is altered as clusters are allocated and deallocated. BITMAP.SYS is updated when the portion of the bitmap in cache is swapped back to disk. Since a portion of the bitmap is always in cache, BITMAP.SYS never reflects the current state of allocated clusters on a disk (unless the disk is dismounted or write-locked).
One of the functions of ANALYZE/DISK_STRUCTURE is to build a current version of BITMAP.SYS from data extracted from INDEXF.SYS, so that BITMAP.SYS accurately reflects the status of free clusters on the disk.
The bad block file contains all the bad blocks on the volume. The system detects bad disk blocks dynamically and prevents their reuse once the files to which they are allocated have been deleted.
The MFD is a file that contains reserved files that control the Files-11 volume directory structure. The MFD lists the known files, in addition to any files or directories that the user enters. The master file directory is itself one of the files (000000.DIR;1) listed in the MFD.
Usually, however, the MFD is used to list the reserved files and users' file directories; users seldom enter files into the MFD, even on private volumes. In fact, on a private volume, it is most convenient for users to create a directory that has the same name as their default directory on a system disk. For an explanation of users' file directories and file specifications, see the OpenVMS User's Manual.
When the Backup utility (BACKUP) creates sequential disk save sets, it stores the save-set file in the MFD.
ANALYZE/DISK_STRUCTURE verifies all files contained in the directory structure by making comparisons to INDEXF.SYS. Any file found in INDEXF.SYS that is not traceable through the directory structure is "lost." ANALYZE/DISK_STRUCTURE places lost files in the top-level directory SYSLOST.DIR if you specified /REPAIR in the command.
The core image file is not used by the operating system.
The volume set list file is used only on relative volume 1 of a volume set. The file contains a list of the labels of all the volumes in the set and the name of the volume set.
ANALYZE/DISK_STRUCTURE uses VOLSET.SYS to locate each volume in the set and confirm the attributes of each volume. Since all volume set information is stored in VOLSET.SYS on relative volume 1, ANALYZE/DISK_STRUCTURE ignores VOLSET.SYS on all other volumes.
The continuation file is used as the extension file identifier when a file crosses from one volume to another volume of a loosely coupled volume set. This file is used for all but the first volume of a sequential disk save set.
The backup log file is reserved for future use.
The pending bad block log file contains a list of suspected bad blocks on the volume that are not listed in the bad block file.
The quota file is a reserved file that is used by the file system to keep track of the disk usage of each UIC on a volume. If you enable disk quota checking for a volume, the records of the file QUOTA.SYS contain all the UICs on the volume. The system constantly updates QUOTA.SYS to reflect the current disk usage, the maximum allowed disk usage, and the permitted overdraft for each UIC.
During the course of its operations, ANALYZE/DISK_STRUCTURE creates a version of QUOTA.SYS in memory that reflects the actual disk usage for each UIC. This version is eventually compared to the disk version of QUOTA.SYS. If ANALYZE/DISK_STRUCTURE detects any disparities in disk usage, ANALYZE/DISK_STRUCTURE notifies you. If you invoked ANALYZE/DISK_STRUCTURE with the /REPAIR qualifier, the disk version of QUOTA.SYS is updated.
The volume security profile includes the volume owner UIC, the volume system-owner-group-world (SOGW) protection mask, and the volume access control list (ACL).
On VAX systems, for reasons of performance, reliability, and security, Files--11 ODS Level 2, a compatible superset of ODS Level 1, is the preferred disk structure on the system. At volume initialization time, Structure Level 2 is the default. (See the INITIALIZE command in the OpenVMS DCL Dictionary.)
On VAX systems, specify ODS Level 1 only for volumes that must be transportable to RSX--11M, RSX--11D, RSX--11M--PLUS, and IAS systems, as these systems support only that structure level. Additionally, you might be required to handle Structure Level 1 volumes transported to OpenVMS from one of these systems.
Where Structure Level 1 volumes are in use on the system, bear in mind the limitations on them that are shown in Table A-4.
Disk | Only Files--11 ODS--2 disks are protected objects. |
Directories | No hierarchies of directories and subdirectories, and no ordering of directory entries (that is, the file names) in any way. RSX--11M, RSX--11D, RSX--11M--PLUS, and IAS systems do not support subdirectories and alphabetical directory entries. |
Disk quotas | Not supported. |
Multivolume files and volume sets | Not supported. |
Placement control | Not supported. |
Caches | No caching of file header blocks, file identification slots, or extent entries. |
System disk | Cannot be a Structure Level 1 volume. |
OpenVMS Cluster access | Local access only; cannot be shared across a cluster. |
Clustered allocation | Not supported. |
Backup home block | Not supported. |
Protection code E | E means "extend" for the RSX--11M operating system but is ignored by OpenVMS. |
File versions | Limited to 32,767; version limits are not supported. |
Enhanced protection features (for example, access control lists) | Not supported. |
Long file names | Not supported. |
RMS journaling | Not supported. |
RMS execution statistics monitoring | Not supported. |
Future enhancements to OpenVMS software will be based primarily on Structure Level 2; therefore, Structure Level 1 volumes might be further restricted in the future.
The tables in this appendix show the time differential factors (TDFs) of various locations in the world. Each table contains a list of locations in a specific region. The information in the tables is believed to be accurate at the time of publication.
Note
For the TDFs of countries in Africa, refer to the map in Figure 5-1.
Table B-1 lists the time differential factors for Europe.
Region | Standard Time TDF |
Daylight Saving Time TDF |
---|---|---|
Great Britain, Ireland | 0:00 | +1:00 |
Western European Time | 0:00 | +1:00 |
Iceland | 0:00 | --- |
Middle European Time | +1:00 | +2:00 |
Poland | +1:00 | +2:00 |
Eastern European Time | +2:00 | +3:00 |
Turkey | +3:00 | +4:00 |
Table B-2 lists the time differential factors for North America.
Region | Standard Time TDF |
Daylight Saving Time TDF |
---|---|---|
U.S./Eastern Time | -5:00 | -4:00 |
U.S./Central Time | -6:00 | -5:00 |
U.S./Mountain Time | -7:00 | -6:00 |
U.S./Pacific Time | -8:00 | -7:00 |
U.S./Indiana (East) | -5:00 | --- |
U.S./Alaska | -9:00 | -8:00 |
U.S./Arizona | -7:00 | --- |
U.S./Navajo | -7:00 | -6:00 |
U.S./Michigan | -5:00 | -4:00 |
U.S./Aleutian Islands | -10:00 | -9:00 |
U.S./Hawaii | -10:00 | --- |
U.S./Samoa | -11:00 | --- |
Canada/Newfoundland | -3:30 | -2:30 |
Canada/Atlantic | -4:00 | -3:00 |
Canada/Eastern | -5:00 | -4:00 |
Canada/Central | -6:00 | -5:00 |
Canada/East--Saskatchewan | -6:00 | --- |
Canada/Mountain | -7:00 | -6:00 |
Canada/Pacific | -8:00 | -7:00 |
Canada/Yukon | -9:00 | -8:00 |
Table B-3 lists the time differential factors for Central and South America.
Region | Standard Time TDF |
Daylight Saving Time TDF |
---|---|---|
Mexico/BajaNorte | -8:00 | -7:00 |
Mexico/BajaSur | -7:00 | --- |
Mexico/General | -6:00 | --- |
Cuba | -5:00 | -4:00 |
Jamaica | -5:00 | -4:00 |
Brazil/East | -3:00 | -2:00 |
Brazil/West | -4:00 | -3:00 |
Brazil/Acre | -5:00 | -4:00 |
Brazil/DeNoronha | -2:00 | -1:00 |
Chile/Regional | -4:00 | -3:00 |
Chile/Easter Island | -6:00 | -5:00 |
Table B-4 lists the time differential factors for Asia.
Region | Standard Time TDF |
Daylight Saving Time TDF |
---|---|---|
PRC (Mainland China) | +8:00 | +9:00 |
ROK (Korea) | +9:00 | +10:00 |
Israel | +3:00 | +4:00 |
Iran | +3:30 | +4:30 |
Japan | +9:00 | --- |
Singapore | +8:00 | --- |
Hong Kong | +8:00 | --- |
ROC (Taiwan) | +8:00 | --- |
Table B-5 lists the time differential factors for the South Pacific.
Region | Standard Time TDF |
Daylight Saving Time TDF |
---|---|---|
Australia/Tasmania | +10:00 | +11:00 |
Australia/Queensland (standard time only) | +10:00 | --- |
Australia/Queensland | +10:00 | +11:00 |
Australia/North | +9:30 | --- |
Australia/West | +8:00 | --- |
Australia/South | +9:30 | +10:30 |
Australia/Victoria | +10:00 | +11:00 |
Australia/New South Wales | +10:00 | +11:00 |
New Zealand | +12:00 | +13:00 |
Table B-6 lists the time differential factors for Antarctica.
Region | Standard Time TDF |
Daylight Saving Time TDF |
---|---|---|
Antarctica | +0:00 | --- |
Following is an alphabetical listing of terms used in the
OpenVMS System Manager's Manual and their definitions.
access control list (ACL): A protection mechanism
using a more refined level of protection than that available with
UIC-based protection. ACLs can be used to grant or deny
access to individual users or groups of users.
access mode: Any of the four processor access modes in
which software executes. Processor access modes prevent system software
from inadvertently performing operations that might damage the system.
Processor access modes are in order from most to least privileged and
protected: kernel, executive, supervisor, and user. When the processor
is in any mode other than kernel mode, the processor is inhibited from
executing privileged instructions.
account: Each system user has an account. When you log
in, you log in under a particular account name and number. This number
informs the system where your files are and what kind of access to
other files and system facilities you should be given.
accounting files: Files where the system stores
information on resource use. Compare with current accounting
file.
active set: In a multiprocessing system, the subset of
processors that have successfully run power-on diagnostics and are
actively participating in system operations. Compare with
available set.
active values: With system parameters, the set of
values that is stored in memory and is used by the active system. When
the system boots, it reads into memory the current values
stored in a parameter file on disk.
adjacent node: In a network, a node that is connected
to your node by a single physical line.
allocation class: In an OpenVMS Cluster environment,
for devices that are dual-ported between two computers, a numeric value
used to create a unique, path-independent device name.
answer file: A file in the form
SYS$UPDATE:product.ANS. The file is created when you install a
product initially, and you specify the Auto-Answer option. The file
contains a record of the answers you entered when you ran VMSINSTAL.COM
to install that product initially.
application service: A LAT service in which
LAN users can access only a specific program. Contrast with
general timesharing service.
area router: In a network, a node that performs
routing operations between areas and within its own area. Also called a
level 2 router. Compare with level 1 router.
autostart feature: A feature that simplifies startup and ensures high availability of execution queues in an OpenVMS Cluster environment. It lets you do the following:
autostart queue: An execution queue that takes
advantage of the autostart feature. When you create a queue,
you can designate it as an autostart queue.
available set: In a multiprocessing system, those
processors that have successfully completed the system's power-on
hardware diagnostics and may or may not be actively involved in the
system. Compare with active set.
backlink: In Files--11 disk structure, a pointer to
the directory in which a file resides.
banner page: A specially formatted page that prints at
the beginning and end of print jobs and files within print jobs. These
pages are helpful in identifying and separating output jobs, and the
files within those jobs, when they are printed.
base process priority: A base priority value that the
system uses to schedule a process. Priorities range from a low of 0 to
a high of 31; 0 through 15 are timesharing priorities and 16 through 31
are real-time priorities. Compare with job scheduling
priority.
batch execution queue: An execution queue that can
accept only batch jobs.
batch job: A detached process that sequentially runs
one or more command procedures. The user defines the list of command
procedures when submitting the job to a batch queue.
batch mode: An execution mode in which you can execute
a command procedure by submitting the procedure to a batch queue. When
resources are available, the system creates a detached process to
execute the commands in the procedure. Usually, processes running in
batch mode execute at a lower process priority, to avoid competing with
interactive users for system resources.
beginning-of-tape (BOT) marker: A piece of
photoreflective tape that delimits the beginning of the writable area
on a tape volume.
binding: On an InfoServer system, a function that
creates a virtual device unit on a local OpenVMS system.
block: On Files--11 disks, the basic unit by which
disk space is allocated (512 8-bit bytes). On magnetic tape, the size
of a block is determined by the user.
boot block: Virtual block 1 of the index file. The
boot (or bootstrap) block is almost always mapped to the logical block
0 of the volume. The book block contains the location and size of the
primary bootstrap image, which is used to boot the system.
Certain processors, in order to boot, must read the boot block to
obtain the location of the primary bootstrap image.
booting: Also called bootstrapping,
the process of loading system software from the system disk into
processor memory. You must install the operating system before you boot
the system for the first time. See also conversational boot
and nonstop boot.
bootstrapping: See booting.
bpi: Bits per inch; a measure used for characters of
data on tape. Also called density.
caching: A performance enhancement in which the system
stores information in memory; this includes information about a disk
volume's free space, file identifications, quota file entries, and file
headers.
capability: On VAX systems, software that makes the
services of the vector processor available to system users.
cathedral windows: Segmented windows created from
mapping windows; useful for reducing the overhead required to read
large files. The Buffered I/O Byte Count Limit (BITLM) limits the
number of cathedral windows a user can create.
circuit: In a network, a communications data path that
connects adjacent nodes. A circuit is not a physical data
path but, rather, a logical connection that operates over a physical
connection (a line). All input and output (I/O) between nodes takes
place over circuits.
cluster: On Files--11 media, a logical grouping of blocks; the basic unit by which disk space is allocated.
See also VAXcluster system, OpenVMS Cluster
system.
CMIP: See Common Management Information
Protocol.
command procedure: A file containing DCL commands and,
optionally, data used by those commands. When you execute a command
procedure, the system reads the file and executes the commands it
contains. This eliminates the need for you to enter each command
separately. You can use command procedures to efficiently perform
routine tasks. A command procedure can also be executed in batch
mode.
command string: The complete specification of a
command, including the command name, command qualifiers, parameters,
and parameter qualifiers. Because a command can be continued on more
than one line, the term is used to define the entire command.
Common Management Information Protocol (CMIP): Draft
standard for network management operations on which DECnet-Plus network
management protocol is based. CMIP is used for encoding network
management operations that can be performed on an entity. CMIP permits
the exchange of information between a director and an agent. CMIP
supersedes the Phase IV Network Information and Control Exchange (NICE)
protocol.
Compact Disc Read-Only Memory (CD--ROM): Computer
discs similar to the CD--ROMs used for audio applications. The major
difference is that CD--ROM computer disc players have a digital (rather
than an audio) interface.
configuration database: In a network, each node has a
configuration database that includes information about the node and
other nodes with which it can communicate. The configuration database
is made up of a permanent database and volatile
database.
connection manager: In an OpenVMS Cluster environment,
the component that dynamically defines the OpenVMS Cluster system and
coordinates participation of computers in the cluster.
conversational boot: A booting operation in which you stop to perform special operations---for example, to change system parameter values---before booting. Contrast with nonstop boot.
Conversational boot operations are common in programming research and
development environments where you must alter operating conditions for
experimentation, testing, and debugging.
6017P076.HTM OSSG Documentation 22-NOV-1996 14:23:09.96
Copyright © Digital Equipment Corporation 1996. All Rights Reserved.