=;The OpenVMS Frequently Asked Questions (FAQ)D

The OpenVMS Frequently Asked Questions (FAQ)



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15.6.2.1.1 Why no shadowing for a Quorum Disk?



EStated simply, Host-Based Volume Shadowing uses the Distributed Lock GManager (DLM) to coordinate changes to membership of a shadowset (e.g. Fremoving a member). The DLM depends in turn on the Connection Manager Cenforcing the Quorum Scheme and deciding which node(s) (and quorum Ddisk) are participating in the cluster, and telling the DLM when it Hneeds to do things like a lock database rebuild operation. So you can't Hintroduce a dependency of the Connection Manager on Shadowing to try to ?pick proper shadowset member(s) to use as the Quorum Disk when GShadowing itself is using the DLM and thus indirectly depending on the DConnection Manager to keep the cluster membership straight---it's a circular dependency.

FSo in practice, folks simply depend on controller-based mirroring (or Hcontroller-based RAID) to protect the Quorum Disk against disk failures A(and dual-redundant controllers to protect against most cases of Gcontroller and interconnect failures). Since this disk unit appears to Ebe a single disk up at the VMS level, there's no chance of ambiguity.X

15.6.2.2 Explain disk (or tape) allocation class settings?



FThe allocation class mechanism provides the system manager with a way Dto configure and resolve served and direct paths to storage devices Hwithin a cluster. Any served device that provides multiple paths should Hbe configured using a non-zero allocation class, either at the MSCP (or GTMSCP) storage controllers, at the port (for port allocation classes), Eor at the OpenVMS MSCP (or TMSCP) server. All controllers or servers Dproviding a path to the same device should have the same allocation 1class (at the port, controller, or server level).

FEach disk (or tape) unit number used within a non-zero disk (or tape) Eallocation class must be unique, regardless of the particular device Fprefix. For the purposes of multi-path device path determination, any Fdisk (or tape) device with the same unit number and the same disk (or Ftape) allocation class configuration is assumed to be the same device.

GIf you are reconfiguring disk device allocation classes, you will want Eto avoid the use of allocation class one ($1$) until/unless you have FFibre Channel storage configured. (Fibre Channel storage specifically 8requires the use of allocation class $1$. eg: $1$DGA0:.)a

15.6.2.2.1 How to configure allocation classes and Multi-Path SCSI?



FThe HSZ allocation class is applied to devices, starting with OpenVMS EV7.2. It is considered a port allocation class (PAC), and all device Hnames with a PAC have their controller letter forced to "A". (You might ?infer from the the text in the "Guidelines for OpenVMS Cluster FConfigurations" that this is something you have to do, though OpenVMS 0will thoughtfully handle this renaming for you.)

>You can force the device names back to DKB by setting the HSZ Gallocation class to zero, and setting the PKB PAC to -1. This will use Fthe host allocation class, and will leave the controller letter alone E(that is, the DK controller letter will be the same as the SCSI port H(PK) controller). Note that this won't work if the HSZ is configured in Gmultibus failover mode. In this case, OpenVMS requires that you use an allocation class for the HSZ.

CWhen your configuration gets even moderately complex, you must pay Bcareful attention to how you assign the three kinds of allocation Cclass: node, port and HSZ/HSJ, as otherwise you could wind up with 7device naming conflicts that can be painful to resolve.

FThe display-able path information is for SCSI multi-path, and permits Fthe multi-path software to distinguish between different paths to the Gsame device. If you have two paths to $1$DKA100, for example by having Htwo KZPBA controllers and two SCSI buses to the HSZ, you would have two >UCBs in a multi-path set. The path information is used by the :multi-path software to distinguish between these two UCBs.

GThe displayable path information describes the path; in this case, the DSCSI port. If port is PKB, that's the path name you get. The device Hname is no longer completely tied to the port name; the device name now Ddepends on the various allocation class settings of the controller, SCSI port or node.

EThe reason the device name's controller letter is forced to "A" when @you use PACs is because a shared SCSI bus may be configured via Hdifferent ports on the various nodes connected to the bus. The port may Ebe PKB on one node, and PKC on the other. Rather obviously, you will Hwant to have the shared devices use the same device names on all nodes. BTo establish this, you will assign the same PAC on each node, and FOpenVMS will force the controller letter to be the same on each node. GSimply choosing "A" was easier and more deterministic than negotiating @the controller letter between the nodes, and also parallels the Gsolution used for this situation when DSSI or SDI/STI storage was used.

ETo enable port allocation classes, see the SYSBOOT command SET/BOOT, +and see the DEVICE_NAMING system parameter.

>This information is also described in the Cluster Systems and 6Guidelines for OpenVMS Cluster Configurations manuals.P

15.6.3 Tell me about SET HOST/DUP and SET HOST/HSC



CThe OpenVMS DCL commands SET HOST/DUP and SET HOST/HSC are used to Hconnect to storage controllers via the Diagnostics and Utility Protocol A(DUP). These commands require that the FYDRIVER device driver be Cconnected. This device driver connection is typically performed by @adding the following command(s) into the system startup command procedure:

On OpenVMS Alpha:

 

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$ RUN SYS$SYSTEM:SYSMAN 9SYSMAN> IO CONNECT FYA0/NOADAPTER/DRIVER=SYS$FYDRIVER 




On OpenVMS VAX:

 

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$ RUN SYS$SYSTEM:SYSGEN "SYSGEN> CONNECT FYA0/NOADAPTER 




EAlternatives to the DCL SET HOST/DUP command include the console SET FHOST command available on various mid- to recent-vintage VAX consoles:

4Access to Parameters on an Embedded DSSI controller:

 

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6SET HOST/DUP/DSSI[/BUS:{0:1}] dssi_node_number PARAMS 




<Access to Directory of tools on an Embedded DSSI controller:

 

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6SET HOST/DUP/DSSI[/BUS:{0:1}] dssi_node_number DIRECT 




0Access to Parameters on a KFQSA DSSI controller:

 

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2SHOW UQSSP ! to get port_controller_number PARAMS 1SET HOST/DUP/UQSSP port_controller_number PARAMS 




EThese console commands are available on most MicroVAX and VAXstation B3xxx series systems, and most (all?) VAX 4xxx series systems. For Dfurther information, see the system documentation and---on most VAX $systems---see the console HELP text.

FEK-410AB-MG, _DSSI VAXcluster Installation and Troubleshooting_, is a Egood resource for setting up a DSSI VMScluster on OpenVMS VAX nodes. H(This manual predates coverage of OpenVMS Alpha systems, but gives good >coverage to all hardware and software aspects of setting up a FDSSI-based VMScluster---and most of the concepts covered are directly Eapplicable to OpenVMS Alpha systems. This manual specifically covers Ethe hardware, which is something not covered by the standard OpenVMS VMScluster documentation.)

kAlso see Section 15.3.3, and for the SCS name of the OpenVMS host see 0Section 5.7.K

15.6.4 How do I rename a DSSI disk (or tape?)



AIf you want to renumber or rename DSSI disks or DSSI tapes, it's ,easy---if you know the secret incantation...

From OpenVMS:

 

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$ RUN SYS$SYSTEM:SYSGEN "SYSGEN> CONNECT FYA0/NOADAPTER SYSGEN> ^Z @$ SET HOST/DUP/SERV=MSCP$DUP/TASK=PARAMS <DSSI-NODE-NAME> ... PARAMS> STAT CONF F<The software version is normally near the top of the display.> PARAMS> EXIT ... 




EFrom the console on most 3000- and 4000-class VAX system consoles... <(Obviously, the system must be halted for these commands...)

Integrated DSSI:

 

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6SET HOST/DUP/DSSI[/BUS:[0:1]] dssi_node_number PARAMS 




KFQSA:

 

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1SET HOST/DUP/UQSSP port_controller_number PARAMS 




FFor information on how to get out into the PARAMS subsystem, also see Hthe HELP at the console prompt for the SET HOST syntax, or see the HELP @on SET HOST /DUP (once you've connected FYDRIVER under OpenVMS).

EOnce you are out into the PARAMS subsystem, you can use the FORCEUNI Coption to force the use of the UNITNUM value and then set a unique DUNITNUM inside each DSSI ISE---this causes each DSSI ISE to use the Cspecfied unit number and not use the DSSI node as the unit number. FOther parameters of interest are NODENAME and ALLCLASS, the node name 0and the (disk or tape) cluster allocation class.

FEnsure that all disk unit numbers used within an OpenVMS Cluster disk Fallocation class are unique, and all tape unit numbers used within an FOpenVMS Cluster tape allocation class are also unique. For details on jthe SCS name of the OpenVMS host, see Section 5.7. For details of SET BHOST/DUP, see Section 15.6.3.]

15.6.5 Where can I get Fibre Channel Storage (SAN) information?

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15.6.6 Which files must be shared in an OpenVMS Cluster?



DThe following files are expected to be common across all nodes in a Dcluster environment, and though SYSUAF is very often common, it can Falso be carefully coordinated---with matching UIC values and matching Dbinary identifier values across all copies. (The most common use of Gmultiple SYSUAF files is to allow different quotas on different nodes. EIn any event, the binary UIC values and the binary identifier values @must be coordinated across all SYSUAF files, and must match the HRIGHTSLIST file.) In addition to the list of files (and directories, in lsome cases) shown in Table 15-1, please review the VMScluster ;documentation, and the System Management documentation.

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Table 15-1 Cluster Common Shared Files
Filename Default Specification
SYSUAF  SYS$SYSTEM:.DAT
 SYSUAFALT  SYS$SYSTEM:.DAT
SYSALF  SYS$SYSTEM:.DAT
 RIGHTSLIST  SYS$SYSTEM:.DAT
 NETPROXY  SYS$SYSTEM:.DAT
 NET$PROXY  SYS$SYSTEM:.DAT
 NETOBJECT  SYS$SYSTEM:.DAT
 NETNODE_REMOTE  SYS$SYSTEM:.DAT
 QMAN$MASTER 1 SYS$SYSTEM:; this is a set of related files
 LMF$LICENSE  SYS$SYSTEM:.LDB
 VMSMAIL_PROFILE  SYS$SYSTEM:.DATA
 VMS$OBJECTS  SYS$SYSTEM:.DAT
 VMS$AUDIT_SERVER  SYS$MANAGER:.DAT
 VMS$PASSWORD_HISTORY  SYS$SYSTEM:.DATA
 NETNODE_UPDATE  SYS$MANAGER:.COM
 VMS$PASSWORD_POLICY  SYS$LIBRARY:.EXE
 LAN$NODE_DATABASE  SYS$SYSTEM:.DAT
 VMS$CLASS_SCHEDULE  SYS$SYSTEM:.DATA
 SYS$REGISTRY 1 SYS$SYSTEM:; this is a set of related files


FIn addition to the documentation, also see the current version of the %file SYS$STARTUP:SYLOGICALS.TEMPLATE.>Specifically, please see the most recent version of this file -available, starting on or after OpenVMS V7.2.

CA failure to have common or (in the case of multiple SYSUAF files) Fsynchronized files can cause problems with batch operations, with the BSUBMIT/USER command, with the general operations with the cluster >alias, and with various SYSMAN and related operations. Object Fprotections and defaults will not necessarily be consistent, as well. EThis can also lead to system security problems, including unintended Daccess denials and unintended object accesses, should the files and ?particularly should the binary identifier values become skewed.K

15.6.7 How can I split up an OpenVMS Cluster?



?Review the VMScluster documentation, and the System Management Hdocumentation. The following are the key points, but are likely not the $only things you will need to change.

BOpenVMS Cluster support is directly integrated into the operating Csystem, and there is no way to remove it. You can, however, remote @site-specific tailoring that was added for a particular cluster configuration.

EFirst: Create restorable image BACKUPs of each of the current system Edisks. If something gets messed up, you want a way to recover, right?

FCreate standalone BACKUP kits for the OpenVMS VAX systems, and create >or acquire bootable BACKUP kits for the OpenVMS Alpha systems.

FUse CLUSTER_CONFIG or CLUSTER_CONFIG_LAN to remove the various system <roots and to shut off boot services and VMScluster settings.

CCreate as many architecture-specific copies of the system disks as Brequired. Realize that the new systems will all likely be booting Gthrough root SYS0---if you have any system-specific files in any other roots, save them.

HRelocate the copies of the VMScluster common files onto each of the new system disks.

HReset the console parameters and boot flags on each system for use on a standalone node.

GReset the VAXCLUSTER and NISCS_LOAD_PEA0 parameters to 0 in SYSGEN and in MODPARAMS.DAT.

:Clobber the VMScluster group ID and password using SYSMAN.

7Reboot the systems seperately, and run AUTOGEN on each.

@Shut off MOP services via NCP or LANCP on the boot server nodes.

HPermanent seperation also requires the duplication of shared files. For la list of the files commonly shared, please see Section 15.6.6.

BAlso see the topics on "cluster divorce" in the Ask The Wizard area.



HFor additional information on the OpenVMS Ask The Wizard (ATW) area and Bfor a pointer to the available ATW Wizard.zip archive, please see iSection 3.8. ATW has been superceded (for new questions) by the ITRC <discussion forums; the area remains available for reference.

bInformation on changing node names is included in Section 5.7.B

15.6.8 Details on Volume Shadowing?



EThis section contains information on host-based volume shadowing; on 9the disk mirroring capabilities available within OpenVMS.c

15.6.8.1 Does volume shadowing require a non-zero allocation classes?



BYes, use of host-based Volume Shadowing requires that the disk(s) 6involved be configured in a non-zero allocation class.

<Edit SYS$SYSTEM:MODPARAMS.DAT to include a declaration of anHnon-zero allocation class, such as setting the host allocation class to the value 7:

 

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ALLOCLASS = 7 




$Then AUTOGEN the system, and reboot.

HYou should now be able to form the shadow set via a command such as the following:

 

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=$ MOUNT dsa1007: /SHADOW=($7$dkb300:,$7$dkb500:) volumelabel 




CWhen operating in an OpenVMS Cluster, this sequence will typically @change the disk names from the SCSNODE prefix (scsnode$dkann) toI the allocation-class prefix ($7$dkannn). This may provide you with the H opportunity to move to a device-independent scheme using logical name H constructs such as the DISK$volumelabel logical names in your startup D and application environments; an opportunity to weed out physical  device references.

FAllocation class one is used by Fibre Channel devices; it can be best Fto use another non-zero allocation class even if Fibre Channel is not /currently configured and not currently planned.




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