=;The OpenVMS Frequently Asked Questions (FAQ)D

The OpenVMS Frequently Asked Questions (FAQ)



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15.2.6 Why can't I use PPP and RAS to connect to OpenVMS Alpha?



HOpenVMS Alpha IP PPP does not presently support authentication, and the CMicrosoft Windows NT option to disable authentication during a RAS Dconnection apparently doesn't currently work---RAS connections will Drequire authentication---and this will thus prevent RAS connections.

HFuture versions of OpenVMS and TCP/IP Services may add this, and future Hversions of Microsoft Windows may permit operations with authentication disabled.^

15.3 OpenVMS and DECnet Networking?



AThe following sections contain information on OpenVMS and DECnet networking.E

15.3.1 Can DECnet-Plus operate over IP?



GYes. To configure DECnet-Plus to operate over IP transport and over IP Fbackbone networks, install and configure DECnet-Plus, and install and configure the PWIPE mechanism available within the currently-installed IP stack. Within G TCP/IP Services, this is a PWIPDRIVER configuration option within the D UCX$CONFIG (versions prior to V5.0) or TCPIP$CONFIG (with V5.0 and  later) configuration tool._

15.3.2 What does "failure on back translate address request" mean?



The error message:

 

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;BCKTRNSFAIL, failure on the back translate address request 




Eindicates that the destination node is running DECnet-Plus, and that Bits naming service (DECnet-Plus DECdns, LOCAL node database, etc) Ecannot locate a name to associate with the source node's address. In Eother words, the destination node cannot determine the node name for 7the node that is the source of the incoming connection.

HUse the DECNET_REGISTER mechanism (on the destination node) to register Hor modify the name(s) and the address(es) of the source node. Check the &namespace on the source node, as well.

HTypically, the nodes involved are using a LOCAL namespace, and the node Hname and address settings are not coherent across all nodes. Also check Dto make sure that the node is entered into its own LOCAL namespace. ?This can be a problem elsewhere, however. Very rarely, a cache Gcorruption has been known to cause this error. To flush the cache, use the command:

 

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$ RUN SYS$SYSTEM:NCL -flush session control naming cache entry "*" 




HAlso check to see that you are using the latest ECO for DECnet-Plus for ?the version you are running. DECnet-Plus can use the following namespaces:



GOf these, searching DNS/BIND and LocalFile, respectively, is often the most appropriate configuration.L

15.3.3 Performing SET HOST/MOP in DECnet-Plus?



/First, issue the NCL command SHOW MOP CIRCUIT *

 

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$ RUN SYS$SYSTEM:NCL SHOW MOP CIRCUIT * 




EAssume that you have a circuit known as FDDI-0 displayed. Here is an Eexample of the SET HOST/MOP command syntax utilized for this circuit:

 

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8$ SET HOST/MOP/ADDRESS=08-00-2B-2C-5A-23/CIRCUIT=FDDI-0 




=Also see Section 15.6.3.Z

15.3.4 How to flush the DECnet-Plus session cache?



 

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$ RUN SYS$SYSTEM:NCL -FLUSH SESSION CONTROL NAMING CACHE ENTRY "*" 


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15.4 How to determine the network hardware address?



EMost Alpha and most VAX systems have a console command that displays Dthe network hardware address. Many systems will also have a sticker Cidentifying the address, either on the enclosure or on the network controller itself.

BThe system console power-up messages on a number of VAX and Alpha Asystems will display the hardware address, particularly on those <systems with an integrated Ethernet network adapter present.

DIf you cannot locate a sticker on the system, if the system powerup Cmessage is unavailable or does not display the address, and if the @system is at the console prompt, start with the console command:

 

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HELP 




GA console command similar to one of the following is typically used to display the hardware address:

 

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SHOW DEVICE SHOW ETHERNET SHOW CONFIG 




FOn the oldest VAX Q-bus systems, the following console command can be @used to read the address directly off the (DELQA, DESQA, or the ;not-supported-in-V5.5-and-later DEQNA) Ethernet controller:

 

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E/P/W/N:5 20001920 




FLook at the low byte of the six words displayed by the above command. H(The oldest VAX Q-bus systems---such as the KA630 processor module used Bon the MicroVAX II and VAXstation II series---lack a console HELP >command, and these systems typically have the primary network Hcontroller installed such that the hardware address value is located at &the system physical address 20001920.)

HIf the system is a VAX system, and another VAX system on the network is ?configured to answer Maintenance and Operations Protocol (MOP) Ebootstrap requests (via DECnet Phase IV, DECnet-Plus, or LANCP), the /MOM$SYSTEM:READ_ADDR.EXE tool can be requested:

 

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B/R5:100 ddcu Bootfile: READ_ADDR 




HWhere ddcu is the name of the Ethernet controller in the above command. AThe primarly local DELQA, DESQA, and DEQNA Q-bus controllers are Eusually named XQA0. An attempt to MOP download the READ_ADDR program Gwill ensue, and (if the download is successful) READ_ADDR will display the hardware address.

FIf the system is running, you can use DECnet or TCP/IP to display the 4hardware address with one of the following commands.

 

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$! DECnet Phase IV $ RUN SYS$SYSTEM:NCP  SHOW KNOWN LINE CHARACTERISTICS 




 

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$! DECnet-Plus $ RUN SYS$SYSTEM:NCL "SHOW CSMA-CD STATION * ALL STATUS 




 

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!$! TCP/IP versions prior to V5.0 $ UCX SHOW INTERFACE/FULL 




 

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"$! TCP/IP versions V5.0 and later $ TCPIP SHOW INTERFACE/FULL 




FA program can be created to display the hardware address, reading the Bnecessary information from the network device drivers. A complete Aexample C program for reading the Ethernet or IEEE 802.3 network Fcontroller hardware address (via sys$qio calls to the OpenVMS network 4device driver(s)) is available at the following URL:



DTo use the DECnet Phase IV configurator tool to watch for MOP SYSID #activity on the local area network:

 

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$ RUN SYS$SYSTEM:NCP ;SET MODULE CONFIGURATOR KNOWN CIRCUIT SURVEILLANCE ENABLED 




FLet the DECnet Phase IV configurator run for at least 20 minutes, and 5preferably longer. Then issue the following commands:

 

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$ RUN SYS$SYSTEM:NCP >SHOW MODULE CONFIGURATOR KNOWN CIRCUIT STATUS TO filename.txt <SET MODULE CONFIGURATOR KNOWN CIRCUIT SURVEILLANCE DISABLED 




DThe resulting file (named filename.txt) can now be searched for the Einformation of interest. Most DECnet systems will generate MOP SYSID Gmessages identifying items such as the controller hardware address and Dthe controller type, and these messages are generated and multicast roughly every ten minutes.

DInformation on the DECnet MOP SYSID messages and other parts of the Emaintenance protocols is included in the DECnet network architecture *specifications referenced in section DOC9.]

15.4.1 How do I reset the LAN (DECnet-Plus NCL) error counters?



On recent OpenVMS releases:

 

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$ RUN SYS$SYSTEM:LANCP 3SET DEVICE/DEVICE_SPECIFIC=FUNCTION="CCOU" devname 


Q

15.4.2 How do I install DECnet Phase IV on VMS 7.1?



BOn OpenVMS V7.1, all DECnet binaries were relocated into separate @installation kits---you can selectively install the appropriate Fnetwork: DECnet-Plus (formerly known as DECnet OSI), DECnet Phase IV, ,and HP TCP/IP Services (often known as UCX).

GOn OpenVMS versions prior to V7.1, DECnet Phase IV was integrated, and Gthere was no installation question. You had to install the DECnet-Plus A(DECnet/OSI) package on the system, after the OpenVMS upgrade or installation completed.

ADuring an OpenVMS V7.1 installation or upgrade, the installation Fprocedure will query you to learn if DECnet-Plus should be installed. GIf you are upgrading to V7.1 from an earlier release or are installing HV7.1 from a distribution kit, simply answer "NO" to the question asking Ayou if you want DECnet-Plus. Then---after the OpenVMS upgrade or Binstallation completes -- use the PCSI PRODUCT INSTALL command to Binstall the DECnet Phase IV binaries from the kit provided on the "OpenVMS software distribution kit.

GIf you already have DECnet-Plus installed and wish to revert, you must Ereconfigure OpenVMS. You cannot reconfigure the "live" system, hence Dyou must reboot the system using the V7.1 distribution CD-ROM. Then <select the DCL ($$$ prompt) option. Then issue the commands:

 

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'$$$ DEFINE/SYSTEM PCSI$SYSDEVICE DKA0: -$$$ DEFINE/SYSTEM PCSI$SPECIFIC DKA0:[SYS0.] =$$$ PRODUCT RECONFIGURE VMS /REMOTE/SOURCE=DKA0:[VMS$COMMON] 




HThe above commands assume that the target system device and system root Bare "DKA0:[SYS0.]". Replace this with the actual target Cdevice and root, as appropriate. The RECONFIGURE command will then Hissue a series of prompts. You will want to reconfigure DECnet-Plus off Bthe system, obviously. You will then want to use the PCSI command DPRODUCT INSTALL to install the DECnet Phase IV kit from the OpenVMS distribution media.

HInformation on DECnet support, and on the kit names, is included in the 4OpenVMS V7.1 installation and upgrade documentation.

HSubsequent OpenVMS upgrade and installation procedures can and do offer 3both DECnet Phase IV and DECnet-Plus installations.q

15.5 How can I send (radio) pages from my OpenVMS system?



CThere are third-party products available to send messages to radio Epaging devices (pagers), communicating via various protocols such as 7TAP (Telocator Alphanumeric Protocol); paging packages.

RamPage (Ergonomic Solutions)@is one of the available packages that can generate and transmit Emessages to radio pagers. Target Alert (Target Systems; formerly the DECalert product) is another.=Networking Dynamics Corp has a product called Pager Plus. TheASystem Watchdog package can also send pages. The Process SoftwareHpackage PMDF can route specific email addresses to a paging service, as well.

DMany commercial paging services provide email contact addresses for Gtheir paging customers---you can simply send or forward email directly +to the email address assigned to the pager.

FSome people implement the sending of pages to radio pagers by sending Ecommands to a modem to take the "phone" off the "hook", and then the Fpaging sequence, followed by a delay, and then the same number that a ?human would dial to send a numeric page. (This is not entirely Hreliable, as the modem lacks "call progress detection", and the program Ecould simply send the dial sequence when not really connected to the 3paging company's telephone-based dial-up receiver.)

jSee Section 13.1 for information on the available catalog of products.f

15.6 OpenVMS, Clusters, Volume Shadowing?



DThe following sections contain information on OpenVMS and Clusters, 8Volume Shadowing, and Cluster-related system parameters.U

15.6.1 OpenVMS Cluster Communications Protocol Details?



AThe following sections contain information on the OpenVMS System ?Communications Services (SCS) Protocol. Cluster terminology is Lavailable in Section 15.6.1.2.1.S

15.6.1.1 OpenVMS Cluster (SCS) over DECnet? Over IP?



>The OpenVMS Cluster environment operates over various network Eprotocols, but the core of clustering uses the System Communications EServices (SCS) protocols, and SCS-specific network datagrams. Direct (full) connectivity is assumed.

FAn OpenVMS Cluster does not operate over DECnet, nor over IP.

&No SCS protocol routers are available.

CMany folks have suggested operating SCS over DECnet or IP over the Cyears, but SCS is too far down in the layers, and any such project Hwould entail a major or complete rewrite of SCS and of the DECnet or IP Gdrivers. Further, the current DECnet and IP implementations have large Etracts of code that operate at the application level, while SCS must @operate in the rather more primitive contexts of the system and Gparticularly the bootstrap---to get SCS to operate over a DECnet or IP Gconnection would require relocating major portions of the DECnet or IP Gstack into the kernel. (And it is not clear that the result would even -meet the bandwidth and latency expectations.)

AThe usual approach for multi-site OpenVMS Cluster configurations Hinvolves FDDI, Memory Channel (MC2), or a point-to-point remote bridge, Dbrouter, or switch. The connection must be transparent, and it must Coperate at 10 megabits per second or better (Ethernet speed), with Glatency characteristics similar to that of Ethernet or better. Various 4sites use FDDI, MC2, ATM, or point-to-point T3 link.W

15.6.1.2 Configuring Cluster SCS for path load balancing?



?This section discusses OpenVMS Cluster communications, cluster Cterminology, related utilities, and command and control interfaces.D

15.6.1.2.1 Cluster Terminology?



FSCS: Systems Communication Services. The protocol used to communicate Ebetween VMSCluster systems and between OpenVMS systems and SCS-based Estorage controllers. (SCSI-based storage controllers do not use SCS.)

GPORT: A communications device, such as DSSI, CI, Ethernet or FDDI. EachG CI or DSSI bus is a different local port, named PAA0, PAB0, PAC0 etc. 9 All Ethernet and FDDI busses make up a single PEA0 port.

EVIRTUAL CIRCUIT: A reliable communications path established between aH pair of ports. Each port in a VMScluster establishes a virtual circuit ' with every other port in that cluster.

DAll systems and storage controllers establish "Virtual Circuits" to ;enable communications between all available pairs of ports.

SYSAP: A "system application"H that communicates using SCS. Each SYSAP communicates with a particular & remote SYSAP. Example SYSAPs include:

(VMS$DISK_CL_DRIVER connects to MSCP$DISK
4The disk class driver is on every VMSCluster system.F MSCP$DISK is on all disk controllers and all VMSCluster systems that ) have SYSGEN parameter MSCP_LOAD set to 1

(VMS$TAPE_CL_DRIVER connects to MSCP$TAPE
4The tape class driver is on every VMSCluster system.F MSCP$TAPE is on all tape controllers and all VMSCluster systems that * have SYSGEN parameter TMSCP_LOAD set to 1

)VMS$VAXCLUSTER connects to VMS$VAXCLUSTER
BThis SYSAP contains the connection manager, which manages cluster ?connectivity, runs the cluster state transition algorithm, and Fimplements the cluster quorum algorithm. This SYSAP also handles lock <traffic, and various other cluster communications functions.

(SCS$DIR_LOOKUP connects to SCS$DIRECTORY
3This SYSAP is used to find SYSAPs on remote systems

MSCP and TMSCP
GThe Mass Storage Control Protocol and the Tape MSCP servers are SYSAPs Gthat provide access to disk and tape storage, typically operating over GSCS protocols. MSCP and TMSCP SYSAPs exist within OpenVMS (for OpenVMS Bhosts serving disks and tapes), within CI- and DSSI-based storage Gcontrollers, and within host-based MSCP- or TMSCP storage controllers. HMSCP and TMSCP can be used to serve MSCP and TMSCP storage devices, and Dcan also be used to serve SCSI and other non-MSCP/non-TMSCP storage devices.

ESCS CONNECTION: A SYSAP on one node establishes an SCS connection to Dits counterpart on another node. This connection will be on ONE AND +ONLY ONE of the available virtual circuits.O

15.6.1.2.2 Cluster Communications Control?



HWhen there are multiple virtual circuits between two OpenVMS systems it Gis possible for the VMS$VAXCLUSTER to VMS$VAXCLUSTER connection to use Dany one of these circuits. All lock traffic between the two systems 1will then travel on the selected virtual circuit.

EEach port has a "LOAD CLASS" associated with it. This load Fclass helps to determine which virtual circuit a connection will use. HIf one port has a higher load class than all others then this port will Fbe used. If two or more ports have equally high load classes then the ?connection will use the first of these that it finds. Prior to Eenhancements found in V7.3-1 and later, the load class is static and Gnormally all CI and DSSI ports have a load class of 14(hex), while the FEthernet and FDDI ports will have a load class of A(hex). With V7.3-1 -and later, the load class values are dynamic.

@For instance, if you have multiple DSSI busses and an FDDI, the GVMS$VAXCLUSTER connection will chose the DSSI bus as this path has the Hsystem disk, and thus will always be the first DSSI bus discovered when the OpenVMS system boots.

?To force all lock traffic off the DSSI and on to the FDDI, for Dinstance, an adjustment to the load class value is required, or the DSSI SCS port must be disabled.

?In addition to the load class mechanisms, you can also use the G"preferred path" mechanisms of MSCP and TMSCP services. This Gallows you to control the SCS connections used for serving remote disk Hand tape storage. The preferred path mechanism is most commonly used to Aexplicitly spread cluster I/O activity over hosts and/or storage Bcontrollers serving disk or tape storage in parallel. This can be Fparticularly useful if your hosts or storage controllers individually Dlack the necessary I/O bandwidth for the current I/O load, and must 7thus aggregate bandwidth to serve the cluster I/O load.

EFor related tools, see various utilities including LAVC$STOP_BUS and BLAVC$START_BUS, and see DCL commands including SET PREFERRED_PATH.c

15.6.1.2.3 Cluster Communications Control Tools and Utilities?



0In most OpenVMS versions, you can use the tools:



FThese tools permit you to disable or enable all SCS traffic on the on the specified paths.

FYou can also use a preferred path mechanism that tells the local MSCP Bdisk class driver (DUDRIVER) which path to a disk should be used. DGenerally, this is used with dual-pathed disks, forcing I/O traffic Fthrough one of the controllers instead of the other. This can be used Fto implement a crude form of I/O load balancing at the disk I/O level.

8Prior to V7.2, the preferred path feature uses the tool:



AIn OpenVMS V7.2 and later, you can use the following DCL command:

 

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$ SET PREFERRED_PATH 




HThe preferred path mechanism does not disable nor affect SCS operations on the non-preferred path.

FWith OpenVMS V7.3 and later, please see the SCACP utility for control ?over cluster communications, SCS virtual circuit control, port selection, and related.N

15.6.2 Cluster System Parameter Settings?



FThe following sections contain details of configuring cluster-related system parameters.d

15.6.2.1 What is the correct value for EXPECTED_VOTES in a VMScluster?



GThe VMScluster connection manager uses the concept of votes and quorum Hto prevent disk and memory data corruptions---when sufficient votes are @present for quorum, then access to resources is permitted. When Esufficient votes are not present, user activity will be blocked. The Gact of blocking user activity is called a "quorum hang", and is better Cthought of as a "user data integrity interlock". This mechanism is Hdesigned to prevent a partitioned VMScluster, and the resultant massive Fdisk data corruptions. The quorum mechanism is expressly intended ;to prevent your data from becoming severely corrupted.

DOn each OpenVMS node in a VMScluster, one sets two values in SYSGEN:AVOTES, and EXPECTED_VOTES. The former is how many votes the node Gcontributes to the VMScluster. The latter is the total number of votes 2expected when the full VMScluster is bootstrapped.

HSome sites erroneously attempt to set EXPECTED_VOTES too low, believing Gthat this will allow when only a subset of voting nodes are present in <a VMScluster. It does not. Further, an erroneous setting in FEXPECTED_VOTES is automatically corrected once VMScluster connections ?to other nodes are established; user data is at risk of severe Ccorruptions during the earliest and most vulnerable portion of the ?system bootstrap, before the connections have been established.

GOne can operate a VMScluster with one, two, or many voting nodes. With Bany but the two-node configuration, keeping a subset of the nodes Hactive when some nodes fail can be easily configured. With the two-node Econfiguration, one must use a primary-secondary configuration (where Hthe primary has all the votes), a peer configuration (where when either Enode is down, the other hangs), or (preferable) a shared quorum disk.

GUse of a quorum disk does slow down VMScluster transitions somewhat -- Fthe addition of a third voting node that contributes the vote(s) that Hwould be assigned to the quorum disk makes for faster transitions---but Bthe use of a quorum disk does mean that either node in a two-node AVMScluster configuration can operate when the other node is down.



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Note

EThe quorum disk must be on a non-host-based shadowed disk, though it Gcan be protected with controller-based RAID. Because host-based volume Fshadowing depends on the lock manager and the lock manager depends on Hthe connection manager and the connection manager depends on quorum, it Gis not technically feasible (nor even particularly reliable) to permit ?host-based volume shadowing to protect the quorum disk.


=If you choose to use a quoum disk, a QUORUM.DAT file will be automaticallyHcreated when OpenVMS first boots and when a quorum disk is specified -- Awell, the QUORUM.DAT file will be created when OpenVMS is booted 4without also needing the votes from the quorum disk.

GIn a two-node VMScluster with a shared storage interconnect, typically ?each node has one vote, and the quorum disk also has one vote. EXPECTED_VOTES is set to three.

FUsing a quorum disk on a non-shared interconnect is unnecessary---the Huse of a quorum disk does not provide any value, and the votes assigned Bto the quorum disk should be assigned to the OpenVMS host serving access to the disk.

DFor information on quorum hangs, see the OpenVMS documentation. For Finformation on changing the EXPECTED_VOTES value on a running system, Fsee the SET CLUSTER/EXPECTED_VOTES command, and see the documentation Hfor the AMDS and Availability Manager tools. Also of potential interest Gis the OpenVMS system console documentation for the processor-specific Cconsole commands used to trigger the IPC (Interrrupt Priority LevelH%x0C; IPL C) handler. (IPC is not available on OpenVMS I64 V8.2.) AMDS, FAvailability Manager, and the IPC handler can each be used to clear a ?quorum hang. Use of AMDS and Availability Manager is generally @recommended over IPC, particularly because IPC can cause CLUEXITH bugchecks if the system should remain halted beyond the cluster sanity I timer limits, and because some Alpha consoles and most (all?) Integrity / consoles do not permit a restart after a halt.

DThe quorum scheme is a set of "blade guards" deliberately Fimplemented by OpenVMS Engineering to provide data integrity---remove Gthese blade guards at your peril. OpenVMS Engineering did not Dimplement the quorum mechanism to make a system manager's life more Fdifficult--- the quorum mechanism was specifically implemented to +keep your data from getting scrambled.




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