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HP OpenVMS Systems Documentation

HP OpenVMS System Management Utilities Reference Manual

Starting with OpenVMS Version 7.2, the serving types are implemented as a bit mask. To specify the type of serving your system will perform, locate the type you want in the following table and specify its value. For some systems, you may want to specify two serving types, such as serving all tapes except those whose allocation class does not match. To specify such a combination, add the values of each type, and specify the sum.

In a mixed-version cluster that includes any systems running OpenVMS Version 7.1-x or earlier, serving all available tapes is restricted to serving all tapes except those whose allocation class does not match the system's allocation class (pre-Version 7.2 meaning). To specify this type of serving, use the value 9, which sets bit 0 and bit 3. The following table describes the serving type controlled by each bit and its decimal value:

Bit	Value When Set	Description
Bit 0	1	Serve all available tapes (locally attached and those connected to HS x and DSSI controllers). Tapes with allocation classes that differ from the system's allocation class (set by the ALLOCLASS parameter) are also served if bit 3 is not set.
Bit 1	2	Serve locally attached (non-HS x and non-DSSI) tapes.
Bit 2	N/A	Reserved.
Bit 3	8	Restrict the serving specified by bit 0. All tapes except those with allocation classes that differ from the system's allocation class (set by the ALLOCLASS parameter) are served. This is pre-Version 7.2 behavior. If your cluster includes systems running OpenVMS Version 7.1- x or earlier, and you want to serve all available tapes, you must specify 9, the result of setting this bit and bit 0.

Although the serving types are now implemented as a bit mask, the values of 0, 1, and 2, specified by bit 0 and bit 1, retain their original meanings:

0 --- Do not serve any tapes (the default for earlier versions of OpenVMS).
1 --- Serve all available tapes.
2 --- Serve only locally attached (non-HSx and non-DSSI) tapes.

If the TMSCP_LOAD system parameter is 0, TMSCP_SERVE_ALL is ignored.

TTY_ALTALARM

TTY_ALTALARM sets the size of the alternate type-ahead buffer alarm. This value indicates at what point an XOFF should be sent to terminals that use the alternate type-ahead buffers with the size specified by the TTY_ALTYPAHD parameter.

TTY_ALTYPAHD

TTY_ALTYPAHD sets the size of the alternate type-ahead buffer. Use this parameter to allow the block mode terminals and communications lines to operate more efficiently.

The default value is usually adequate. Do not exceed the maximum value of 32767 when setting this parameter.

TTY_AUTOCHAR (D)

TTY_AUTOCHAR sets the character the terminal driver echoes when the job controller has been notified.

TTY_BUF

TTY_BUF sets the default line width for terminals.

TTY_CLASSNAME

TTY_CLASSNAME provides the 2-character prefix for the terminal class driver name that is required when booting. Changing the prefix can be useful when debugging a new terminal driver.

TTY_DEFCHAR

TTY_DEFCHAR sets the default characteristics for terminals, using a code derived by summing the following hexadecimal values:

Characteristic	Value (Hex)	Function
PASSALL	1	Passall.
NOECHO	2	Noecho mode.
NOTYPEAHEAD ¹	4	No type-ahead buffer.
ESCAPE	8	Escape sequence processing.
HOSTSYNC	10	Host can send XON and XOFF.
TTSYNC	20	Terminal can send XON and XOFF.
SCRIPT	40	Internal use only.
LOWER	80	Lowercase.
MECHTAB	100	Mechanical tabs.
WRAP	200	Wraparound at end of line.
CRFILL ¹	400	Perform carriage return fill.
LFFILL ¹	800	Perform line feed fill.
SCOPE	1000	Terminal is a scope.
REMOTE	2000	Internal use only.
EIGHTBIT	8000	Eight-bit terminal.
MBXDSABL	10000	Disable mailbox.
NOBRDCST	20000	Prohibit broadcast.
READSYNC	40000	XON and XOFF on reads.
MECHFORM	80000	Mechanical form feeds.
HALFDUP	100000	Set for half-duplex operation.
MODEM	200000	Set for modem signals.
PAGE	FF000000	Page size. Default is 24.

¹Do not set this characteristic as the default in TTY_DEFCHAR.

Where a condition is false, the value is 0.

The upper byte is the page length. The default characteristics are 24 lines per page, terminal synchronization, wraparound, lowercase, scope, and full-duplex.

TTY_DEFCHAR2

TTY_DEFCHAR2 sets a second longword of default terminal characteristics. The default characteristics are represented as a code that is derived by summing the following hexadecimal values:

Characteristic	Value (Hex)	Function
LOCALECHO	1	Enable local echo terminal logic; use with the TTY_DEFCHAR NOECHO characteristic.
AUTOBAUD	2	Enable autobaud detection.
HANGUP	4	Hang up on logout.
MODHANGUP	8	Allow modification of HANGUP without privileges.
BRDCSTMBX	10	Allow sending of broadcasts to mailboxes.
XON	20	(No effect in this parameter.)
DMA	40	(No effect in this parameter.)
ALTYPEAHD	80	Use the alternate type-ahead parameters.
SETSPEED	100	Clear to allow setting of speed without privileges.
DCL_MAILBX	200	Function reserved for HP use only.
DECCRT4	400	Terminal is DIGITAL CRT Level 4.
COMMSYNC	800	Enable flow control using modem signals.
EDITING	1000	Line editing allowed.
INSERT	2000	Sets default mode for insert.
FALLBACK	4000	Do not set this bit with SYSGEN.
DIALUP	8000	Terminal is a dialup line.
SECURE	10000	Guarantees that no process is connected to terminal after Break key is pressed.
DISCONNECT	20000	Allows terminal disconnect when a hangup occurs.
PASTHRU	40000	Terminal is in PASTHRU mode.
SYSPWD	80000	Log in with system password only.
SIXEL	100000	Sixel graphics.
DRCS	200000	Terminal supports loadable character fonts.
PRINTER	400000	Terminal has printer port.
APP_KEYPAD	800000	Notifies application programs of state to set keypad on exit.
ANSICRT	1000000	Terminal conforms to ANSI CRT programming standards.
REGIS	2000000	Terminal has REGIS CRT capabilities.
BLOCK	4000000	Block mode terminal.
AVO	8000000	Terminal has advanced video.
EDIT	10000000	Terminal has local edit capabilities.
DECCRT	20000000	Terminal is a DIGITAL CRT.
DECCRT2	40000000	Terminal is a DIGITAL CRT Level 2.
DECCRT3	80000000	Terminal is a DIGITAL CRT Level 3.

The defaults are AUTOBAUD and EDITING.

TTY_DEFCHAR3

(Alpha and Integrity servers) TTY_DEFCHAR3 allows a user to set a bit so that the OpenVMS terminal driver remaps CTRL/H to Delete. HP recommends that you not set this bit as a systemwide default.

Characteristic	Value (Hex)	Function
TT3$M_BS	10	When this bit is set, the OpenVMS terminal console remaps CTRL/H to Delete.

For more information, see the SET TERM and SHOW TERM commands in the HP OpenVMS DCL Dictionary.

TTY_DEFPORT

TTY_DEFPORT provides flag bits for port drivers. Bit 0 set to 1 indicates that the terminal controller does not provide automatic XON/XOFF flow control. This bit should not be set for HP controllers, but it is needed for some foreign controllers. Currently only the YCDRIVER (DMF32, DMZ32) uses this bit. The remaining bits are reserved for future use. This special parameter should be modified only if recommended by HP.

TTY_DIALTYPE

TTY_DIALTYPE provides flag bits for dialups. Bit 0 is 1 for United Kingdom dialups and 0 for all others. Bit 1 controls the modem protocol used. Bit 2 controls whether a modem line hangs up 30 seconds after seeing CARRIER if a channel is not assigned to the device. The remaining bits are reserved for future use. See the OpenVMS I/O User's Reference Manual for more information about flag bits.

TTY_DMASIZE (D)

TTY_DMASIZE specifies a number of characters in the output buffer. Below this number, character transfers are performed; above this number, DMA transfers occur if the controller is capable of DMA I/O.

TTY_PARITY

TTY_PARITY sets terminal default parity.

TTY_RSPEED

TTY_RSPEED defines the receive speed for terminals. If TTY_RSPEED is 0, TTY_SPEED controls both the transmit and the receive speed. Maximum value is 20. This parameter is only applicable for controllers that support split-speed operations, such as the DZ32 and the DMF32.

TTY_SCANDELTA

TTY_SCANDELTA sets the interval for polling terminals for dialup and hangup events. Shorter intervals use more processor time; longer intervals may result in missing a hangup event.

TTY_SILOTIME

TTY_SILOTIME defines the interval at which the DMF32 hardware polls the input silo for received characters. The DMF32 asynchronous terminal controller can delay the generation of a single input interrupt until multiple characters have accumulated in the input silo. TTY_SILOTIME specifies the number of milliseconds that the characters are allowed to accumulate prior to the generation of an input interrupt by the hardware.

Note

The remainder of this discussion is of interest to customers who use Digi Edgeport hardware.

TTY_SILOTIME controls latency, trading throughput and system overhead for latency. The default value for TTY_SILOTIME is 8. This value is multiplied by 100 and is used as a count of the number of times to send a query to the device for more data after a character transmit or receive is performed.

If no input (or no subsequent output) is seen after 800 responses to the query, the driver stops sending queries to the device and waits for an input interrupt. Reducing the TTY_SILOTIME value allows the device to buffer more data, with slightly higher latency.

Increasing the value of TTY_SILOTIME makes the device more sensitive to latency but decreases buffering and overall throughput; it also adds more system and USB overhead. Setting TTY_SILOTIME to zero causes the driver to send input queries to the device continually. This setting causes the lowest latency, the highest system overhead, and the lowest throughput possible.

TTY_SPEED

TTY_SPEED sets the systemwide default speed for terminals. Low byte is transmit speed, and high byte is receive speed. If high byte is set to 0, receive speed is identical to transmit speed. Maximum value is 20. Baud rates are defined by the $TTDEF macro.

TTY_TIMEOUT (D)

TTY_TIMEOUT sets the number of seconds before a process associated with a disconnected terminal is deleted. The default value (900 seconds) is usually adequate. Note that using values for TTY_TIMEOUT greater than one year (value %X01E13380) can cause overflow errors and result in a disconnected device timing out immediately.

TTY_TYPAHDSZ

TTY_TYPAHDSZ sets the size of the terminal type-ahead buffer. The default value is usually adequate. Do not exceed the maximum value of 32767 when setting this parameter.

UAFALTERNATE (G,M)

UAFALTERNATE enables or disables the assignment of SYSUAF as the logical name for SYSUAFALT, causing all references to the user authorization file (SYSUAF) to be translated to SYS$SYSTEM:SYSUAFALT. Use of the normal user authorization file (SYS$SYSTEM:SYSUAF) can be restored by deassigning the system logical name SYSUAF. This parameter should be set on (1) only when the system is being used by a restricted set of users. You must create a user authorization file named SYSUAFALT prior to setting UAFALTERNATE to 1.

USERD1 (D)

USERD1 is reserved for definition at the user's site. The reserved longword is referenced by the symbol SGN$GL_USERD1.

On Alpha and Integrity servers, this symbol is in the SYS$LOADABLE_IMAGES:SYS$BASE_IMAGE module.

USERD2 (D)

USERD2 is reserved for definition at the user's site. The reserved longword is referenced by the symbol SGN$GL_USERD2.

On Alpha and Integrity servers, this symbol is in the SYS$LOADABLE_IMAGES:SYS$BASE_IMAGE module.

USER3

USER3 is a parameter that is reserved for definition at the user's site. The reserved longword is referenced by the symbol SGN$GL_USER3.

On Alpha and Integrity servers, this symbol is in the SYS$LOADABLE_IMAGES:SYS$BASE_IMAGE module.

USER4

USER4 is a parameter that is reserved for definition at the user's site. The reserved longword is referenced by the symbol SGN$GL_USER4.

On Alpha and Integrity servers, this symbol is in the SYS$LOADABLE_IMAGES:SYS$BASE_IMAGE module.

VAXCLUSTER (A)

VAXCLUSTER controls loading of the cluster code. Specify one of the following:

Value	Description
0	Never form or join a cluster.
1	Base decision of whether to form (or join) a cluster or to operate standalone on the presence of cluster hardware.
2	Always form or join a cluster.

The default value is 1.

VCC_FLAGS (A)

(Alpha only) The static system parameter VCC_FLAGS enables and disables file system data caching. If caching is enabled, VCC_FLAGS controls which file system data cache is loaded during system startup.

Value	Description
0	Disables file system data caching on the local node and throughout the OpenVMS Cluster. In an OpenVMS Cluster, if caching is disabled on any node, none of the other nodes can use the extended file cache or the virtual I/O cache. They can't cache any file data until that node either leaves the cluster or reboots with VCC_FLAGS set to a nonzero value.
1	Enables file system data caching and selects the Virtual I/O Cache. This is the default for VAX systems.
2	Enables file system data caching and selects the extended file cache. This is the default for Alpha systems.

Note

On Integrity servers, the volume caching product ([SYS$LDR]SYS$VCC.EXE) is not available. XFC caching is the default caching mechanism. Setting the VCC_FLAGS parameter to 1 is equivalent to not loading caching at all or to setting VCC_FLAGS to 0.

VCC_MAXSIZE (A)

(Alpha and Integrity servers) The static system parameter VCC_MAXSIZE controls the size of the virtual I/O cache. VCC_MAXSIZE, which specifies the size in blocks, is 3,700,000 by default.

The virtual I/O cache cannot shrink or grow. Its size is fixed at system startup.

To adjust the XFC size, use the VCC_MAX_CACHE system parameter.

VCC_MAX_CACHE (D)

(Alpha and Integrity servers) The dynamic system parameter VCC_MAX_CACHE controls the maximum size of the extended file cache. It specifies the size in megabytes. By default, VCC_MAX_CACHE has a special value of --1 for people who do not want to tune their systems manually; this value means that at system startup, the maximum size of the extended file cache is set to 50 percent of the physical memory on the system.

The extended file cache can automatically shrink and grow, depending on your I/O workload and how much spare memory your system has. As your I/O workload increases, the cache automatically grows, but never to more than the maximum size. When your application needs memory, the cache automatically shrinks.

The value of VCC_MAX_CACHE at system startup sets an upper limit for the maximum size of the extended file cache. You cannot increase the maximum size of VCC_MAX_CACHE beyond its value at boot time. For example, if VCC_MAX_CACHE is 60 MB at system startup, you can then set VCC_MAX_CACHE to 40, which decreases the maximum size to 40 MB. If you then set VCC_MAX_CACHE to 80, the maximum size is only increased to 60 MB, the value set at system startup.

Note that VCC_MAX_CACHE is a semi-dynamic parameter. If you change its value, you must enter the DCL command SET CACHE/RESET for any changes to take effect immediately. Otherwise, it might take much more time for the changes to take effect.

If you are using the reserved memory registry to allocate memory permanently, you must set the VCC$MIN_CACHE_SIZE entry in the reserved memory registry to a value less than or equal to VCC_MAX_CACHE at system startup time.

For instructions on setting permanent memory allocations for the cache, see the HP OpenVMS System Manager's Manual.

VCC_MAX_IO_SIZE (D)

(Alpha and Integrity servers) The dynamic system parameter VCC_MAX_IO_SIZE controls the maximum size of I/O that can be cached by the extended file cache. It specifies the size in blocks. By default, the size is 127 blocks.

Changing the value of VCC_MAX_IO_SIZE affects reads and writes to volumes currently mounted on the local node, as well as reads and writes to volumes mounted in the future.

If VCC_MAX_IO_SIZE is 0, the extended file cache on the local node cannot cache any reads or writes. However, the system is not prevented from reserving memory for the extended file cache during startup if a VCC$MIN_CACHE_SIZE entry is in the reserved memory registry.

VCC_MAX_LOCKS

(Alpha and Integrity servers) VCC_MAX_LOCKS is a special parameter reserved for HP use only. Extended file cache will use this parameter in future versions.

VCC_PAGESIZE

(Alpha and Integrity servers) VCC_PAGESIZE is a special parameter reserved for HP use only. Extended file cache will use this parameter in future versions.

VCC_READAHEAD (D)

(Alpha and Integrity servers) The dynamic system parameter VCC_READAHEAD controls whether the extended file cache can use read-ahead caching. Read-ahead caching is a technique that improves the performance of applications that read data sequentially.

By default VCC_READAHEAD is 1, which means that the extended file cache can use read-ahead caching. The extended file cache detects when a file is being read sequentially in equal-sized I/Os, and fetches data ahead of the current read, so that the next read instruction can be satisfied from cache.

To stop the extended file cache from using read-ahead caching, set VCC_READAHEAD to 0.

Changing the value of VCC_READAHEAD affects volumes currently mounted on the local node, as well as volumes mounted in the future.

Readahead I/Os are totally asynchronous from user I/Os and only take place if sufficient system resources are available.

VCC_RSVD

(Alpha and Integrity servers) VCC_RSVD is a special parameter reserved for HP use only. Extended file cache will use this parameter in future versions.

VCC_WRITEBEHIND

(Alpha and Integrity servers) VCC_WRITEBEHIND is reserved for HP use only. Extended file cache will use this parameter in future versions.

VCC_WRITE_DELAY

(Alpha and Integrity servers) VCC_WRITE_DELAY is reserved for HP use only.

VHPT_SIZE

(Integrity servers only) VHPT_SIZE is the number of kilobytes to allocate for the virtual hash page table (VHPT) on each CPU in the system:

0 indicates that no VHPT is allocated.
1 indicates that OpenVMS is to choose a default size that is appropriate for your system configuration.

If a VHPT is created, the smallest size is 32KB. The VHPT_SIZE must be a power of 2 KB in size. If the number specified is not a power of 2, OpenVMS chooses a VHPT size to use for your system that is close to the number specified.

If insufficient memory is available during system startup, OpenVMS might choose a smaller size for the VHPT of each CPU.

A summary of possible values for VHPT_SIZE is in the following table:

Value	Description
0	Do not create a VHPT on each CPU.
1	(default) OpenVMS chooses a VHPT of an appropriate size for each CPU.
n	Create a VHPT of nKB for each CPU, where n is a power of 2 that is 32 or greater. (The maximum value, however, is platform-dependent.)

VIRTUALPAGECNT (A,G,M)

On VAX systems, VIRTUALPAGECNT sets the maximum number of virtual pages that can be mapped for any one process. A program is allowed to divide its virtual space between the P0 and P1 tables in any proportion.

If you use SYS$UPDATE:LIBDECOMP.COM to decompress libraries and the VIRTUALPAGECNT setting is low, make sure you set the PGFLQUOTA field in the user authorization file to at least twice the size of the library.

At installation time, AUTOGEN automatically sets an appropriate value for VIRTUALPAGECNT. The value depends on the particular configuration---the type and number of graphics adapters on the system, if any exist. You cannot set VIRTUALPAGECNT below the minimum value required for your graphics configuration.

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