Document revision date: 15 July 2002

The following sections explain new functionality available for SCA circuits and ports and new support for SCS dynamic load class. In addition, you can independently enable or disable checksumming on individual PEdriver virtual circuits (VCs). These changes provide a more dynamic connection environment for improving overall performance in an OpenVMS Cluster system.

4.16.8.1 Ability to Set Port and Circuit Priorities

OpenVMS Cluster code has always attempted to assign SCS connections automatically to a circuit on the highest performance cluster interconnect. These assignments were based on the interconnect-specific load class value. Automatic circuit selection does not always produce connection assignments that are optimal for a customer's particular performance or availability requirements. Unfortunately, no mechanism has existed to override automatic circuit selection. This problem has been corrected in OpenVMS Version 7.3--1.

Beginning with OpenVMS Version 7.3--1, you can exercise direct management control over the circuits chosen for SCS connections. To tune your cluster to your specific performance or availability requirements, now you can override automatic selection of the circuit with the highest load class value.

To override automatic circuit selection, use either the SCACP utility or the Availability Manager to assign a management priority value to a specific circuit or SCA port. (A circuit's current priority value is the sum of the local port's management-assigned priority and the management priority value assigned to that circuit.)

Connections are assigned to a circuit with the highest priority. If multiple circuits have the highest priority value, then the circuit with the highest load class is selected. A change in a circuit's current priority has one of the following effects:

• If a circuit's new priority value is higher than another circuit's current priority, the connection moves to the circuit with the higher current priority.
• If a circuit's new priority value is lower than another circuit's current priority, the connection moves to the circuit with the highest current priority.

Prior to OpenVMS Version 7.3--1, checksumming could be enabled or disabled on all of the circuits of a node only. This sometimes resulted in unnecessary use of the CPU for circuits on which the additional robustness of checksumming was not needed. Beginning with OpenVMS Version 7.3--1, you can enable or disable checksumming on individual LAN circuits. This lets you specify the use of checksumming for only those circuits where it is needed, such as circuits between the sites of a disaster-tolerant cluster.

4.16.8.3 New SCS Dynamic Load Class Support

Prior to OpenVMS Version 7.3--1, the load class of SCS circuits was determined only by the port's hard-coded load class value. As a result, CI or DSSI circuits were chosen over a GigaBit Ethernet circuit. Beginning with OpenVMS Version 7.3-1, PEdriver dynamically updates the load class value of its SCS circuits to reflect the performance of the underlying LAN path or paths currently in use.

If the circuits have the same priority, a change in a circuit's load class has one of the following effects:

• If a circuit's new load class value is higher than another circuit's current load class, the connection moves to the higher load class circuit.
• If a circuit's new load class value is lower than another circuit's load class, the connection moves to the circuit with the highest load class.

New features for the OpenVMS Registry include two enhancements to the Registry Control Program (REG$CP) and performance improvement through indexing.

4.17.1 Database Version Support

The Registry Control Program, REG$CP, has been enhanced to support the creation of distinct Registry database versions. The CREATE DATABASE command now accepts a /VERSION qualifier. For OpenVMS Version 7.3--1, a Version 1 or Version 2 database may be specified. By default, CREATE DATABASE creates a Version 2 database.

4.17.2 Value Type Support

In addition to value types of SZ, EXPAND_SZ, MULTI_SZ, and DWORD, the Registry Control Program, REG$CP, has been enhanced to support the BINARY value type when creating or modifying values (/TYPE_CODE=BINARY). When listing values with BINARY value type, the data is displayed in hexidecimal radix.

Creating and modifying values has also been enhanced with the addition of the /INPUT qualifer to allow the value data to be read from a file. The input data type is specified with embedded keywords in the file records. These keywords are compatible with those found in an exported database file.

The storage data type, as specified by the /TYPE_CODE qualifier, is independent of the input data type. For example, you may specify the value type as SZ (Unicode string) but input the value data in hexidecimal.

Combined, these features allow large amounts of raw data to be entered via REG$CP. By contrast, entering the data with the /DATA qualifier and the DWORD data type, while allowing raw data to be input, imposes restrictions on the length of the data. Similarly, entering SZ value types with /DATA, while not imposing a length restriction, does impose a restriction on the type of data that can be input, that is, you can enter only Unicode strings. The command line also restricts the amount of data that can be input with /DATA. The /INPUT qualifier provides a way to overcome these restrictions.

4.17.3 New Registry Database Version

The performance of the OpenVMS NT Registry has been improved in Version 7.3-1. This was accomplished primarily by indexing the Registry database. This, however, resulted in the need to create a new Registry database version.

The Registry server will continue to support the previous database format, Version 1.0; however, to take advantage of the indexing, you must convert the current database to Version 2.0.

Converting a Version 1 database to Version 2 is optional. Do not convert the Registry database if you plan to run Registry servers on nodes in a mixed-version cluster, while upgrading your cluster. Registry servers on nodes running versions of OpenVMS prior to Version 7.3--1 would not be able to access a Version 2 database.

For further information on converting an OpenVMS Registry database, refer to the COM, Registry, and Events for OpenVMS Developer's Guide.

4.18 SHOW CLUSTER Utility Adds New Fields

The OpenVMS Show Cluster utility (SHOW CLUSTER) is used to monitor nodes in an OpenVMS Cluster and to display information about cluster-specific activity and performance. It has been enhanced to provide additional information about virtual circuits and local ports.

Table 4-4 describes the new fields that you can use with the CIRCUITS class to display virtual circuit information.

Table 4-4 CIRCUITS Class New Fields

Field name	Description
LD_CLASS	The circuit's current capacity rating.
MGT_PRIORITY	Priority value assigned to the circuit by management action.
PRIORITY	Circuit's current priority, which is the sum of the management priorities assigned to the circuit and the associated local port.

Table 4-5 describes the new fields that you can use with the LOCAL_PORTS class to display additional local port information.

Table 4-5 LOCAL_PORTS Class New Fields

Field name	Description
LP_LD_CLASS	Hard-coded capacity value of the port, based on the megabits per second rate of the interconnect of the port.
LP_PRIORITY	Management priority assigned to the port.

For more information about the SHOW CLUSTER utility, refer to the OpenVMS System Management Utilities Reference Manual.

4.19 New Method for Naming Spawned Subprocesses

The way OpenVMS names spawned subprocesses has been changed to improve performance.

DCL_CTLFLAGS is a bitmask used to alter default behavior for certain commands on a systemwide basis. At present, only the low bit of the bitmask is defined. The low bit controls the default process-name assignment for a subprocess created using the SPAWN command or LIB$SPAWN routine.

Prior to OpenVMS Version 7.3--1, if no process name was supplied, the system constructed a name by appending _n to the username, where n was the next available non-duplicate integer for any process currently in the system. For example, the first spawned process from user SYSTEM would be called SYSTEM_1, the second, SYSTEM_2, and so on. The next available number was chosen, as soon as a gap was found.

A problem with this technique is that determining the next available number is very expensive in terms of performance, because the mechanism attempts to create the process by incrementing names until one is found that is unique. When several subprocesses already exist, the cost of creating the subprocess iteratively becomes even more expensive. When many processes are in the same OpenVMS group, the cost multiplies because process names must be unique throughout the group.

Beginning with OpenVMS Version 7.3--1, the default-constructed process name for subprocesses has changed. Instead of incrementally searching for the next unique number, a random number is chosen to append to the username. Therefore, the first processes that are spawned from user SYSTEM might be SYSTEM_154, SYSTEM_42, SYSTEM_87, and so on. This procedure results in a very high probability of finding a unique name on the first try, because it is unlikely that the same number is already in use. This greatly reduces the cost of process creation, and applications that rely on spawned subprocesses might see a dramatic performance improvement due to this change.

However, some applications might rely on the prior method of assigning subprocess names. The DCL_CTLFLAGS parameter is available to allow you to configure the system as necessary.

Bit 0 of DCL_CTLFLAGS selects the behavior for assigning default subprocess names:

• If the bit is clear, the new behavior is used. If you do not specify a process name, the system assigns the username with a random number suffix. This is the default setting.
• If the bit is set, the prior behavior is used. If you do not specify a process name, the system assigns the username with the next available number.

The SYSMAN utility has new qualifiers for the existing RESERVED_MEMORY ADD and RESERVED_MEMORY MODIFY commands and two new commands, described in Table 4-7.

Table 4-6 New SYSMAN Command Qualifiers

Command	Qualifier	Description
RESERVED_MEMORY ADD	/RAD	Specifies the RAD for the reservation you want to make in the Reserved Memory Registry data file.
RESERVED_MEMORY MODIFY	/RAD	Modifes an existing RAD in the Reserved Memory Registry data file.
	/NEW_RAD	Specifies the RAD you want to substitute in the Reserved Memory Registry data file.

Table 4-7 describes the new SYSMAN commands in OpenVMS Version 7.3--1.

Table 4-7 New SYSMAN Utility Commands

Command	Description
RESERVED_MEMORY EXTEND	The RESERVED_MEMORY ADD command reserves an amount of physical memory, referred to as a memory reservation. Use the RESERVED_MEMORY EXTEND command when you want to add memory sections to accommodate more than one resource affinity domain (RAD) for a single memory reservation. It has two qualifiers: /RAD Specifies one ore more RADs for a memory section. /NORAD Adds a memory section without specifying a RAD.
RESERVED_MEMORY LIST	Previews a reservation as it is currently stored in the Reserved Memory Registry data file. If you don't specify a reservation, all current reservations are displayed.

4.21 New System Parameters

The following sections describe system parameters that are new in OpenVMS Version 7.3--1.

4.21.1 DCL_CTLFLAGS

The new system parameter DCL_CTLFLAGS allows users to continue to use the previous default behavior for assigning subprocess names on a systemwide basis when processes are spawned. Refer to Section 4.19 for more information.

4.21.2 DELPRC_EXIT

Use DELPRC_EXIT to control $DELPRC system service options that call exit handlers prior to final cleanup and deletion of a process. The following table describes these options:

Option	Description
0	Disable the exit handler functionality with $DELPRC.
4	Execute kernel-mode exit handlers.
5 (default)	Execute exec- and more privileged-mode exit handlers.
6	Execute supervisor- and more privileged-mode exit handlers.
7	Execute user- and more privileged-mode exit handlers.

DELPRC_EXIT is a dynamic parameter.

4.21.3 MPDEV_AFB_INTVL

MPDEV_AFB_INTVL specifies the automatic failback interval in seconds. The automatic failback interval is the minimum number of seconds that must elapse before the system attempts another failback from an MSCP path to a direct path on the same device.

MPDEV_POLLER must be ON to enable automatic failback. You can disable automatic failback without disabling the poller by setting MPDEV_AFB_INTVL to 0. The default is 300 seconds.

4.21.4 RMS_SEQFILE_WBH

RMS_SEQFILE_WBH can enable the RMS write-behind feature as a system default for any unshared sequential disk file if the file is opened for image I/O with write access specified. The following table describes the possible settings:

Setting	Description
0 (default)	Do not enable write-behind feature. Preserve prior behavior of using write-behind only if the user requests it by setting RAB$V_WBH in RAB$L_ROP.
1	Enable write-behind feature as system default, including the allocation of at least two local buffers.

RMS_SEQFILE_WBH is a dynamic parameter.

4.22 New Capabilities for SCACP Utility

Beginning with OpenVMS Version 7.3--1, you can use SCACP to manage SCA communications on all OpenVMS Cluster interconnects. These interconnects are in addition to SCA use of LAN devices and LAN paths, which was supported beginning in OpenVMS Version 7.3.

4.22.1 Cluster Ports and Circuits

SCACP allows you to display port and circuit information for any cluster interconnect. You can also set the management priority field in ports or circuits. This lets you optimize the cluster's choice of circuits and ports used for cluster configuration.

4.22.2 New Commands and Qualifiers

Table 4-8 describes the new SCACP SET and SHOW commands in OpenVMS Version 7.3--1 and lists their qualifiers.

Table 4-8 New SCACP SET and SHOW Commands and Their Qualifiers

Command	Function
SET CIRCUIT	Allows a user to set a management priority value for the selected circuit or circuits. This command can be used with the following qualifiers: /EXCLUDE=(nodename[/PORT=portname[/RSTATION=n]][,...]) Allows you to exclude a specific circuit to a node. If multiple circuits to the same node exist, you can use the /PORT and /RSTATION qualifiers to uniquely identify the circuit. /PORT=portname[/RSTATION=n] If multiple circuits to the same node exist, you can use the /PORT and /RSTATION qualifiers to uniquely identify the circuit. You can use the /RSTATION qualifier only in conjunction with the /PORT qualifier for the selected circuit or circuits. /PRIORITY=n Sets the management priority value for the selected circuits. n can be any value between -127 and +127.
SET PORT	Allows a user to set a management priority value for the selected port or ports. This command can be used with the following qualifiers: /EXCLUDE=(portname[,...]) Excludes specific ports from the operation. /PRIORITY=n Sets the management priority value for the selected ports. n can be any value between -127 and +127.
SHOW CIRCUIT (nodenames)	Shows information about all circuits between this node and other cluster nodes, including LAN circuit information. This command can be used with the following qualifiers: /EXCLUDE=(nodename[/PORT=portname[/RSTATION=n]][,...]) /EXCLUDE Allows you to exclude a specific circuit to a node. If multiple circuits to the same node exist, you can use the /PORT and /RSTATION qualifiers to uniquely identify the circuit. /PORT=portname[/RSTATION=n] If multiple circuits to the same node exist, you can use the /PORT and /RSTATION qualifiers to uniquely identify the circuit. You can use the /RSTATION qualifier only in conjunction with the /PORT qualifier.
SHOW PORT	Displays information about all SCA ports on the node, including the LAN port, PEA0. This command can be used with the following qualifiers: /EXCLUDE=(portname[,...]) Excludes specific port names from the display. You cannot use wildcards to specify port names. /OUTPUT=filespec Creates the specified file and directs the output of the command to this file.

Table 4-9 describes the new SCACP command qualifiers in OpenVMS Version 7.3--1.

OpenVMS Alpha Version 7.3--1 supports the KZPEA, an Ultra3 SCSI host adapter that offers a maximum bus speed of 160 MB/s. PKAdriver is the software component that supports KZPEA. The KZPEA is supported for direct-attached storage only.

OpenVMS Alpha Version 7.3--1 also provides Fast Path support for the KZPEA. Fast Path support is designed for use in a multiprocessor system. Fast Path automatically redirects I/O from the primary CPU to different CPUs. You can change it either programmatically or by DCL commands.

For more information about Fast Path support, refer to the OpenVMS I/O User's Reference Manual.

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