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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:
If the TMSCP_LOAD system parameter is 0, TMSCP_SERVE_ALL is ignored.
The default value is usually adequate. Do not exceed the maximum value of 32767 when setting this parameter.
| 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. |
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.
| 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.
| Characteristic | Value (Hex) | Function |
|---|---|---|
| TT3$M_BS | 10 | When this bit is set, the OpenVMS terminal console remaps CTRL/H to Delete. |
For more information, see the SET TERM and SHOW TERM commands in the HP OpenVMS DCL Dictionary.
The remainder of this discussion is of interest to customers who use Digi Edgeport hardware. |
TTY_SILOTIME controls latency, trading throughput and system overhead for latency. The default value for TTY_SILOTIME is 8. This value is multiplied by 100 and is used as a count of the number of times to send a query to the device for more data after a character transmit or receive is performed.
If no input (or no subsequent output) is seen after 800 responses to the query, the driver stops sending queries to the device and waits for an input interrupt. Reducing the TTY_SILOTIME value allows the device to buffer more data, with slightly higher latency.
Increasing the value of TTY_SILOTIME makes the device more sensitive to latency but decreases buffering and overall throughput; it also adds more system and USB overhead. Setting TTY_SILOTIME to zero causes the driver to send input queries to the device continually. This setting causes the lowest latency, the highest system overhead, and the lowest throughput possible.
On Alpha and Integrity servers, this symbol is in the SYS$LOADABLE_IMAGES:SYS$BASE_IMAGE module.
On Alpha and Integrity servers, this symbol is in the SYS$LOADABLE_IMAGES:SYS$BASE_IMAGE module.
On Alpha and Integrity servers, this symbol is in the SYS$LOADABLE_IMAGES:SYS$BASE_IMAGE module.
On Alpha and Integrity servers, this symbol is in the SYS$LOADABLE_IMAGES:SYS$BASE_IMAGE module.
| Value | Description |
|---|---|
| 0 | Never form or join a cluster. |
| 1 | Base decision of whether to form (or join) a cluster or to operate standalone on the presence of cluster hardware. |
| 2 | Always form or join a cluster. |
| Value | Description |
|---|---|
| 0 |
Disables file system data caching on the local node and throughout the
OpenVMS Cluster.
In an OpenVMS Cluster, if caching is disabled on any node, none of the other nodes can use the extended file cache or the virtual I/O cache. They can't cache any file data until that node either leaves the cluster or reboots with VCC_FLAGS set to a nonzero value. |
| 1 | Enables file system data caching and selects the Virtual I/O Cache. This is the default for VAX systems. |
| 2 | Enables file system data caching and selects the extended file cache. This is the default for Alpha systems. |
On Integrity servers, the volume caching product ([SYS$LDR]SYS$VCC.EXE) is not available. XFC caching is the default caching mechanism. Setting the VCC_FLAGS parameter to 1 is equivalent to not loading caching at all or to setting VCC_FLAGS to 0. |
The virtual I/O cache cannot shrink or grow. Its size is fixed at system startup.
To adjust the XFC size, use the VCC_MAX_CACHE system parameter.
The extended file cache can automatically shrink and grow, depending on your I/O workload and how much spare memory your system has. As your I/O workload increases, the cache automatically grows, but never to more than the maximum size. When your application needs memory, the cache automatically shrinks.
The value of VCC_MAX_CACHE at system startup sets an upper limit for the maximum size of the extended file cache. You cannot increase the maximum size of VCC_MAX_CACHE beyond its value at boot time. For example, if VCC_MAX_CACHE is 60 MB at system startup, you can then set VCC_MAX_CACHE to 40, which decreases the maximum size to 40 MB. If you then set VCC_MAX_CACHE to 80, the maximum size is only increased to 60 MB, the value set at system startup.
Note that VCC_MAX_CACHE is a semi-dynamic parameter. If you change its value, you must enter the DCL command SET CACHE/RESET for any changes to take effect immediately. Otherwise, it might take much more time for the changes to take effect.
If you are using the reserved memory registry to allocate memory permanently, you must set the VCC$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.
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$MIN_CACHE_SIZE entry is in the reserved memory registry.
By default VCC_READAHEAD is 1, which means that the extended file cache can use read-ahead caching. The extended file cache detects when a file is being read sequentially in equal-sized I/Os, and fetches data ahead of the current read, so that the next read instruction can be satisfied from cache.
To stop the extended file cache from using read-ahead caching, set VCC_READAHEAD to 0.
Changing the value of VCC_READAHEAD affects volumes currently mounted on the local node, as well as volumes mounted in the future.
Readahead I/Os are totally asynchronous from user I/Os and only take place if sufficient system resources are available.
If a VHPT is created, the smallest size is 32KB. The VHPT_SIZE must be a power of 2 KB in size. If the number specified is not a power of 2, OpenVMS chooses a VHPT size to use for your system that is close to the number specified.
If insufficient memory is available during system startup, OpenVMS might choose a smaller size for the VHPT of each CPU.
A summary of possible values for VHPT_SIZE is in the following table:
| Value | Description |
|---|---|
| 0 | Do not create a VHPT on each CPU. |
| 1 | (default) OpenVMS chooses a VHPT of an appropriate size for each CPU. |
| n | Create a VHPT of nKB for each CPU, where n is a power of 2 that is 32 or greater. (The maximum value, however, is platform-dependent.) |
If you use SYS$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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