Document revision date: 19 July 1999

By default, outgoing LAT connections are disabled on a node. To allow users to use the SET HOST/LAT connection to establish LAT connections from the node, you must edit LAT$SYSTARTUP.COM to enable outgoing connections. For more details on using the SET HOST/LAT command for outgoing LAT connections, refer to the description of that command in the OpenVMS DCL Dictionary.

Commands to enable outgoing connections are included in the LAT$SYSTARTUP.COM file provided by Compaq. Enable the command of your choice by removing the exclamation point (!) that precedes it, or add a similar command to meet your needs. For more information, refer to the /CONNECTIONS and /USER_GROUPS qualifiers to the LATCP command SET NODE in the OpenVMS System Management Utilities Reference Manual.

To attain optimal SET HOST/LAT performance and forward port performance, you should set the system parameter TTY_ALTYPAHD to 1500 and reboot.

If you want to set up your node only as a service node with incoming connections enabled, editing LAT$SYSTARTUP.COM is not necessary. However, you might edit LAT$SYSTARTUP.COM to do one or more of the following tasks:

• Create more than one service on a node
• Create special application services
• Set up LAT printers
• Enable outgoing LAT connections (to allow a node to act as a terminal server node)
• Tailor node characteristics; for example, to assign special service announcements or connections to the LAN

The following example is a sample of an edited LAT$SYSTARTUP.COM procedure that creates services, creates and sets ports, and sets nodes to allow incoming and outgoing connections.

$! $! LAT$SYSTARTUP.COM -- LAT Startup Commands Specific to Site $! $! Use this command procedure to customize the LAT characteristics for $! the local node. These commands, which should serve as examples, $! will set up a LAT service name SYS$NODE and default identification $! SYS$ANNOUNCE. The LAT service name and identification will default $! to SYS$NODE and SYS$ANNOUNCE unless you specify a service name and $! identification as arguments to the command line that invokes $! LAT$STARTUP.COM: $! $ @SYS$STARTUP:LAT$STARTUP $! $! You can specify other node and service characteristics (such as group $! codes) as arguments to this command line, as shown below. $! $! Argument Function $! --------- -------- $! $! P1 Name of the service to be created. If not supplied, a $! service will be created with the same name as the node. $! $! P2,P3,P4 Parameters and qualifiers to the SET NODE command. $! $! P5 Parameters and qualifiers to the SET SERVICE command. $! P5 is only used if P1 is specified. More than one $! argument may be supplied by enclosing the string in $! quotes. $! $! Example: $ @SYS$STARTUP:LAT$STARTUP HAWK "/IDENTIFICATION=" - $! """""Development node""""" $! $! Please review and edit this file for possible additions and deletions $! that you wish to make. Future software updates will not overwrite the $! changes made to this file. $! $ required_privileges = "OPER" $ prev_privs = f$setprv(required_privileges) $ if .not. f$privilege(required_privileges) then goto no_privileges $ lcp := $latcp $! $! --------------------- Modify Node Characteristics ------------------------ $! $ lcp set node 'p2' 'p3' 'p4' $! $! Some examples: $! $! ** Allow incoming connections only $! $! lcp set node /connections=incoming /groups=(enable=(12,40,43,73),disable=0) $! lcp set node /connections=incoming /groups=enable=(0-255) $! $ LCP SET NODE /CONNECTIONS=INCOMING /GROUPS=(ENABLE=(12,40,43,73),DISABLE=0) $! $! ** Allow outgoing connections only $! $! lcp set node /connections=outgoing /user_groups=enable=(24,121-127) $! lcp set node /connections=outgoing /user_groups=(enable=0-255) /node_limit=50 $! $! ** Enable incoming and outgoing connections $! $! lcp set node /connections=both /group=enable=(43,73) /user=enable=(44,56) $! lcp set node /connections=both /group=enable=(0-255) /user=enable=(0-255) $! $! $! -------------------- Modify Service Characteristics ---------------------- $! $ if p1 .eqs. "" $ then $ lcp create service $ else $ lcp create service 'p1' 'p5' $ endif $! ------------------------- Start LAT Protocol ----------------------------- $! $ lcp set node /state=on $! $! $! ------------------------- Create and Map Ports --------------------------- $! $! Some examples: $! $! lcp create port lta101: /dedicated $! lcp create port lta102: /application $! lcp create port lta103: /application $! lcp create port /nolog/logical=(name=ln03$mgmt, table=system, mode=executive) $ $ LCP CREATE PORT LTA1: /NOLOG $ LCP CREATE PORT LTA20: /NOLOG $ $! lcp set port lta101: /dedicated /service=graphics $! lcp set port lta102: /node=server_1 /port=port_1 $! lcp set port lta103: /node=server_2 /service=laser $! lcp set port ln03$mgmt: /node=server_3 /service=ln03_printers $! $ LCP SET PORT LTA1: /APPLICATION/NODE=TERM_SERVER_1 /PORT=PORT_6 $ LCP SET PORT LTA20: /APPLICATION/NODE=TERM_SERVER_2 /PORT=PORT_6 $! $exit: $ prev_privs = f$setprv(prev_privs) $ exit $! $no_privileges: $ write sys$output "Insufficient privileges to execute LATCP commands." $ write sys$output "Requires ",required_privileges," privileges." $ goto exit

24.7 Managing the LATACP Database Size

On OpenVMS nodes, another component of the LAT software, the LAT Ancillary Control Process (LATACP), maintains the database of available nodes and services. The nodes and services can be those that are multicast from remote LAT nodes, or they can consist of the local node and one or more local services that you create on your own system. The maximum size of this database is dependent on the value of the system parameter CTLPAGES.

After you enter a LATCP command, you might get the following response:

%LAT-W-CMDERROR, error reported by command executor -LAT-F-ACPNOCTL, insufficient resources - ACP CTL/P1 space limit reached

If so, this signifies that the database size has reached the CTLPAGES limit. You can correct the situation in one of three ways:

• Reduce the size of the database by reducing the node limit. Use the LATCP command SHOW NODE to display the node limit; use the command SET NODE/NODE_LIMIT to change it. For more information, refer to the OpenVMS System Management Utilities Reference Manual.
• Reduce the size of the database by reducing the user group codes that are enabled on the node. Use the LATCP command SHOW NODE to display the enabled user group codes; use the command SET NODE/USER_GROUPS=DISABLE to disable some of them. For more information, refer to the OpenVMS System Management Utilities Reference Manual.
  If you choose this step, you must also edit your startup procedures to change the user groups that are enabled each time the system reboots. For more information, see Section 24.6.
• Extend the size of the database by increasing the value of the system parameter CTLPAGES. As a general rule, note that every unit of CTLPAGES that you increase is roughly equivalent to six additional nodes or services that will be stored in the database.
  After you change CTLPAGES, you must reboot the system for the changed value to take effect. Make sure you add the increased value of CTLPAGES to the AUTOGEN parameter file MODPARAMS.DAT. For more information about changing values of system parameters, see Section 14.2.

This chapter describes what you must do if you want to run software that uses DECdtm services, such as ACMS, DECintact, Oracle Rdb, and RMS Journaling.

Information Provided in This Chapter

This chapter describes the following tasks:

Task	Section
Planning transaction logs	Section 25.2
Planning for a DECnet-Plus network	Section 25.3
Creating transaction logs	Section 25.4
Monitoring transaction performance	Section 25.5
Checking whether a transaction log is too small	Section 25.6
Changing the size of a transaction log	Section 25.7
Moving a transaction log	Section 25.8
Dismounting a disk	Section 25.9
Adding a node	Section 25.10
Removing a node	Section 25.11
Disabling DECdtm services	Section 25.12
Enabling DECdtm services	Section 25.13

The map in Figure 25-1 shows the tasks, and the order in which to do them.

This chapter explains the following concepts:

Concept	Section
Understanding transaction logs	Section 25.1
Understanding transaction groups	Section 25.3.2.2

Figure 25-1 Managing DECdtm Services

25.1 Understanding Transaction Logs

Before a node can execute DECdtm transactions, you must create a transaction log for the node. In an OpenVMS Cluster, create a transaction log for each node in the cluster. Use the Log Manager Control Program (LMCP) utility to create and manage transaction logs.

DECdtm services use the logical name SYS$JOURNAL to find transaction logs. You must define SYS$JOURNAL to point to the directories that contain transaction logs.

25.2 Planning Transaction Logs

The size and location of a transaction log can affect transaction performance. Before you create a transaction log, decide the size and location of the transaction log.

Later, you can change the size of a transaction log, or move it. However, careful planning at this stage reduces the need for future changes.

This section describes:

Task	Section
Deciding the size of a transaction log	Section 25.2.1
Deciding the location of a transaction log	Section 25.2.2

25.2.1 Deciding the Size of a Transaction Log

When you create a transaction log, you can specify its size. The default size is 4000 blocks; this gives acceptable performance on most systems.

If you know the expected rate of transactions, Compaq suggests the following formula to calculate the transaction log size:
size = 40 * rate
where:

size	is the size of the transaction log in blocks.
rate	is the average number of transactions executed per second.

If you do not know the rate of transactions, accept the default size of 4000 blocks.

25.2.2 Deciding the Location of a Transaction Log

You may need to choose between speed and either availability or reliability. For example, if the node is a workstation, you may choose to sacrifice speed for availability and reliability by putting the node's transaction log on a shadowed HSC--based disk, instead of on a faster disk attached to the workstation.

In a cluster environment, try to distribute the transaction logs across different disks. Having more than one transaction log on a disk can lead to poor transaction performance.

This section contains the following information to help you plan for using DECdtm in a DECnet-Plus network:

• Planning your DECnet-Plus namespace
• Planning SCSNODE names in your DECnet-Plus network

DECdtm does not support multiple DECnet-Plus namespaces.

This means that if you want to use software that uses DECdtm services, you cannot use both a local namespace and a DECdns namespace.

25.3.2 Planning SCSNODE Names in Your DECnet-Plus Network

SCSNODE is a system parameter that defines the name of the computer. You must follow certain rules when choosing SCSNODE names if you have a DECnet-Plus network and you want to perform DECdtm transactions that span either different OpenVMS Clusters or different standalone computers.

25.3.2.1 Rules for SCSNODE Names

• The SCSNODE name of each computer in a transaction group must be different from:
  • The SCSNODE names of the other computers in the transaction group; SCSNODE names must be unique within a transaction group
  • The DECnet simple names of other computers on the same local root
  • The DECnet synonyms of the other computers in the entire network
  
  For an explanation of transaction groups, see Section 25.3.2.2.
• If a computer is in an OpenVMS Cluster, its SCSNODE name must also be different from:
  • The DECnet simple names of the other computers in the same cluster
  • The DECnet simple names of computers on the same local root as other cluster members

A transaction group is a group of computers involved in DECdtm transactions whose SCSNODE names must obey the rules described in Section 25.3.2.1.

A transaction group conforms to the following guidelines:

• Each computer belongs to no more than one transaction group.
• All the computers in an OpenVMS Cluster belong to the same transaction group.
• If a single transaction spans computers A and B, then computers A and B belong to the same transaction group.

Figure 25-2 shows an example of a transaction group.

Figure 25-2 Transaction Group

All nine computers shown in the figure are in the same transaction group because:

• A transaction spans a computer in cluster FRED and a computer in cluster BILL. This means that the four computers in cluster FRED and the four computers in cluster BILL are in the same transaction group.
• A transaction spans standalone computer TOM and a computer in cluster BILL. This means that the standalone computer TOM is in the same transaction group as the computers in cluster BILL.

Before a node can perform DECdtm transactions, you must create a transaction log for the node. In an OpenVMS Cluster environment, create a transaction log for each node.

How to Perform This Task

1. For each node, decide the size and location of the transaction log, using the guidelines in Section 25.2. Remember that the disks must have enough contiguous space to hold the transaction logs.
2. If you are in a cluster environment, make sure that the disks on which you want to create the transaction logs are mounted clusterwide.
3. Decide in which directories you want to create the transaction logs. You may want to create new directories for the transaction logs.
4. Define SYS$JOURNAL to point to the directories in which you want to create the transaction logs:

   DEFINE/SYSTEM/EXECUTIVE_MODE SYS$JOURNAL dirspec[,...]

   where dirspec is the full specification of a directory in which you want to create one or more transaction logs. List all the directories that will contain transaction logs. You can list the directories in any order.
   In a cluster environment, use SYSMAN to define SYS$JOURNAL clusterwide.

5. Edit the SYS$MANAGER:SYLOGICALS.COM command procedure to include the SYS$JOURNAL definition.
   If you created node-specific versions of SYLOGICALS.COM, edit all the versions.
6. Create one transaction log for each node, using LMCP's CREATE LOG command:

   CREATE LOG [/SIZE=size] dirspecSYSTEM$node.LM$JOURNAL

   where:

   size	is the size of the transaction log in blocks. By default, the size of the transaction log is 4000 blocks.
   dirspec	is the full specification of the directory in which you want to create the transaction log.
   node	is the name of the node.

7. Make sure DECdtm services are enabled as follows:

   Step	Action
   a.	Check whether the logical SYS$DECDTM_INHIBIT is defined: $ SHOW LOGICAL SYS$DECDTM_INHIBIT
   b.	Is SYS$DECDTM_INHIBIT defined? Yes DECdtm services are disabled. Enable DECdtm services by following the instructions in Section 25.13. No DECdtm services are enabled.

Example

This example shows how to create transaction logs in an OpenVMS Cluster that consists of two nodes whose SCSNODE names are BLUE and RED. Neither node has a node-specific version of SYLOGICALS.COM.

Decide the size and location of the transaction logs:

Node	Size of Log (in Blocks)	Disk
BLUE	5000	DUA1
RED	4000	DUA2

Mount the disks clusterwide:

$ MOUNT/CLUSTER/SYSTEM DUA1: LOG1 $ MOUNT/CLUSTER/SYSTEM DUA2: LOG2

Create directories for the transaction logs:

$ CREATE/DIRECTORY DISK$LOG1:[LOGFILES] $ CREATE/DIRECTORY DISK$LOG2:[LOGFILES]

Define SYS$JOURNAL:

$ RUN SYS$SYSTEM:SYSMAN SYSMAN> SET ENVIRONMENT/CLUSTER SYSMAN> DO DEFINE/SYSTEM/EXECUTIVE_MODE SYS$JOURNAL - _SYSMAN> DISK$LOG1:[LOGFILES], DISK$LOG2:[LOGFILES] SYSMAN> EXIT

Edit the SYS$MANAGER:SYLOGICALS.COM command procedure to include the following line:

$ ! $ DEFINE/SYSTEM/EXECUTIVE_MODE SYS$JOURNAL DISK$LOG1:[LOGFILES], - DISK$LOG2:[LOGFILES] $ !

Create the transaction logs:

$ RUN SYS$SYSTEM:LMCP LMCP> CREATE LOG/SIZE=5000 DISK$LOG1:[LOGFILES]SYSTEM$BLUE.LM$JOURNAL LMCP> CREATE LOG DISK$LOG2:[LOGFILES]SYSTEM$RED.LM$JOURNAL LMCP> EXIT

Make sure DECdtm services are enabled:

$ SHOW LOGICAL SYS$DECDTM_INHIBIT %SHOW-S-NOTRAN, no translation for logical name SYS$DECDTM_INHIBIT

SYS$DECDTM_INHIBIT is undefined, so DECdtm services are enabled.

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