HP OpenVMS Systems Documentation

Guidelines for OpenVMS Cluster Configurations

There is an OpenVMS name for each Fibre Channel storage adapter, for each path from the storage adapter to the storage subsystem, and for each storage device. These sections apply to both disk devices and tape devices, except for Section 7.4.2.3, which is specific to disk devices. Tape device names are described in Section 7.5.

7.4.2.1 Fibre Channel Storage Adapter Names

Fibre Channel storage adapter names, which are automatically assigned by OpenVMS, take the form FGx0 :

• FG represents Fibre Channel.
• x represents the unit letter, from A to Z.
• 0 is a constant.

The naming design places a limit of 26 adapters per system. This naming may be modified in future releases to support a larger number of adapters.

Fibre Channel adapters can run multiple protocols, such as SCSI and LAN. Each protocol is a pseudodevice associated with the adapter. For the initial implementation, just the SCSI protocol is supported. The SCSI pseudodevice name is PGx0 , where x represents the same unit letter as the associated FGx0 adapter.

These names are illustrated in Figure 7-13.

Figure 7-13 Fibre Channel Initiator and Target Names

With the introduction of multipath SCSI support, as described in Chapter 6, it is necessary to identify specific paths from the host to the storage subsystem. This is done by concatenating the SCSI pseudodevice name, a decimal point (.), and the WWID of the storage subsystem port that is being accessed. For example, the Fibre Channel path shown in Figure 7-13 is named PGB0.4000-1FE1-0000-0D04.

Refer to Chapter 6 for more information on the display and use of the Fibre Channel path name.

7.4.2.3 Fibre Channel Disk Device Identification

The four identifiers associated with each FC disk device are shown in Figure 7-14.

Figure 7-14 Fibre Channel Disk Device Naming

The logical unit number (LUN) is used by the system as the address of a specific device within the storage subsystem. This number is set and displayed from the HSG or HSV console by the system manager. It can also be displayed by the OpenVMS SDA utility.

Each Fibre Channel disk device also has a WWID to provide permanent, unique identification of the device. The HSG or HSV device WWID is 128 bits. Half of this identifier is the WWID of the HSG or HSV that created the logical storage device, and the other half is specific to the logical device. The device WWID is displayed by the SHOW DEVICE/FULL command, the HSG or HSV console and the AlphaServer console.

The third identifier associated with the storage device is a user-assigned device identifier. A device identifier has the following attributes:

• User assigned at the HSG or HSV console.
• User must ensure it is cluster unique.
• Moves with the device.
• Can be any decimal number from 0 to 32766, except for MSCP served devices.
  If the FC disk device is MSCP served, the device identifier is limited to 9999. This restriction will be removed in a future release.

The device identifier has a value of 567 in Figure 7-14. This value is used by OpenVMS to form the device name so it must be unique throughout the cluster. (It may be convenient to set the device identifier to the same value as the logical unit number (LUN). This is permitted as long as the device identifier is unique throughout the cluster.)

A Fibre Channel storage disk device name is formed by the operating system from the constant $1$DGA and a device identifier, nnnnn. Note that Fibre Channel disk device names use an allocation class value of 1 whereas Fibre Channel tape device names use an allocation class value of 2, as described in Section 7.5.2.1. The only variable part of the name is its device identifier, which you assign at the HSG or HSV console. Figure 7-14 shows a storage device that is known to the host as $1$DGA567.

The following example shows the output of the SHOW DEVICE/FULL display for this device:

$ SHOW DEVICE/FULL $1$DGA567:

Disk $1$DGA567: (WILD8), device type HSG80, is online, mounted, file-oriented
    device, shareable, device has multiple I/O paths, served to cluster via MSCP
    Server, error logging is enabled.

    Error count                   14    Operations completed            6896599
    Owner process                 ""    Owner UIC                      [SYSTEM]
    Owner process ID        00000000    Dev Prot            S:RWPL,O:RWPL,G:R,W
    Reference count                9    Default buffer size                 512
    WWID   01000010:6000-1FE1-0000-0D00-0009-8090-0630-0008
    Total blocks            17769177    Sectors per track                   169
    Total cylinders             5258    Tracks per cylinder                  20
    Host name                "WILD8"    Host type, avail Compaq AlphaServer GS160 6/731, yes
    Alternate host name     "H2OFRD"    Alt. type, avail AlphaServer 1200 5/533 4MB, yes
    Allocation class               1

    Volume label      "S5SH_V72_SSS"    Relative volume number                0
    Cluster size                  18    Transaction count                     9
    Free blocks             12811860    Maximum files allowed            467609
    Extend quantity                5    Mount count                           6
    Mount status              System    Cache name          "_$1$DGA8:XQPCACHE"
    Extent cache size             64    Maximum blocks in extent cache  1281186
    File ID cache size            64    Blocks currently in extent cache1260738
    Quota cache size               0    Maximum buffers in FCP cache       1594
    Volume owner UIC           [1,1]    Vol Prot    S:RWCD,O:RWCD,G:RWCD,W:RWCD

  Volume Status:  ODS-2, subject to mount verification, file high-water marking,
      write-back caching enabled.
  Volume is also mounted on H2OFRD, FIBRE3, NORLMN, BOOLA, FLAM10.

  I/O paths to device              5
  Path PGA0.5000-1FE1-0000-0D02  (WILD8), primary path.
    Error count                    0    Operations completed              14498
  Path PGA0.5000-1FE1-0000-0D03  (WILD8), current path.
    Error count                   14    Operations completed            6532610
  Path PGA0.5000-1FE1-0000-0D01  (WILD8).
    Error count                    0    Operations completed              14481
  Path PGA0.5000-1FE1-0000-0D04  (WILD8).
    Error count                    0    Operations completed              14481
  Path MSCP (H2OFRD).
    Error count                    0    Operations completed             320530

This section describes the configuration requirements and user commands necessary to utilize the Fibre Channel tape functionality. Fibre Channel tape functionality refers to the support of SCSI tapes and SCSI tape libraries in an OpenVMS Cluster system with shared Fibre Channel storage. The SCSI tapes and libraries are connected to the Fibre Channel by a Fibre-to-SCSI bridge. Currently, two bridges are available: the Modular Data Router (MDR) and the Network Storage Router (NSR).

7.5.1 Minimum Hardware Configuration

Following is the minimum Fibre Channel tape hardware configuration:

• Alpha or Integrity system with supported FC HBA
• Fibre-to-SCSI bridge:
  • Network Storage Router (NSR)
    The NSR must also be connected to a switch and not directly to an Alpha system.
    OpenVMS recommends that the NSR be set to indexed mode.
    The indexed map should be populated in Target/Bus priority order to ensure that the controller LUN is mapped to LUN 0. Also, be careful to avoid conflicting IDs, as documented in the HP StorageWorks network storage router M2402 user guide (order number 269782-003).
  • Modular Data Router (MDR), minimum firmware revision 1170
    The MDR must be connected to a switch and not directly to an Alpha system. Furthermore, the MDR must be in SCSI Command Controller (SCC) mode, which is normally the default. If the MDR is not in SCC mode, use the command SetSCCmode On at the MDR console.
    Tape devices and tape library robots must not be set to SCSI target ID 7, since that ID is reserved for use by the MDR.
• Fibre Channel switch
• Tape library, for example:
  • MSL5000 series
  • ESL9000 series
  • TL891
  • TL895
• Individual tapes, for example:
  • SDLT 160/320
  • SDLT 110/220
  • HP Ultrium 460
  • DLT8000
  • TZ89

This section provides detailed background information about Fibre Channel Tape device naming.

Tape and medium changer devices are automatically named and configured using the SYSMAN IO FIND and IO AUTOCONFIGURE commands described in Section 7.5.3. System managers who configure tapes on Fibre Channel should refer directly to this section for the tape configuration procedure.

7.5.2.1 Tape and Medium Changer Device Names

Fibre Channel tapes and medium changers are named using a scheme similar to Fibre Channel disk naming.

On parallel SCSI, the device name of a directly attached tape implies the physical location of the device; for example, MKB301 resides on bus B, SCSI target ID 3, and LUN 1. Such a naming scheme does not scale well for Fibre Channel configurations, in which the number of targets or nodes can be very large.

Fibre Channel tape names are in the form $2$MGAn. The letter for the controller is always A, and the prefix is $2$. The device mnemonic is MG for tapes and GG for medium changers. The device unit n is automatically generated by OpenVMS.

The name creation algorithm chooses the first free unit number, starting with zero. The first tape discovered on the Fibre Channel is named $2$MGA0, the next is named $2$MGA1, and so forth. Similarly, the first medium changer detected on the Fibre Channel is named $2$GGA0. The naming of tapes and medium changers on parallel SCSI buses remains the same.

Note the use of allocation class 2. Allocation class 1 is already used by devices whose name is keyed by a user-defined identifier (UDID), as with HSG Fibre Channel disks ($1$DGAnnnn) and HSG console command LUNs ($1$GGAnnnn).

An allocation class of 2 is used by devices whose names are obtained from the file, SYS$DEVICES.DAT. The names are based on a worldwide identifier (WWID) key, as described in the following sections. Also note that, while GG is the same mnemonic used for both medium changers and HSG Command Console LUNs (CCLs), medium changers always have an allocation class of 2 and HSG CCLs an allocation class of 1.

Tape and medium changer names are automatically kept consistent within a single OpenVMS Cluster system. Once a tape device is named by any node in the cluster, all other nodes in the cluster automatically choose the same name for that device, even if this overrides the first free unit number algorithm. The chosen device name remains the same through all subsequent reboot operations in the cluster.

If multiple nonclustered Alpha systems exist on a SAN and need to access the same tape device on the Fibre Channel, then the upper-level application must provide consistent naming and synchronized access.

7.5.2.2 Use of Worldwide Identifiers (WWIDs)

For each Fibre Channel tape device name, OpenVMS must uniquely identify the physical device that is associated with that name.

In parallel SCSI, directly attached devices are uniquely identified by their physical path (port/target/LUN). Fibre Channel disks are uniquely identified by user-defined identifiers (UDIDs). These strategies are either unscalable or unavailable for Fibre Channel tapes and medium changers.

Therefore, the identifier for a given Fibre Channel tape or medium changer device is its worldwide identifier (WWID). The WWID resides in the device firmware and is required to be unique by the Fibre Channel standards.

WWIDs can take several forms, for example:

• IEEE registered WWID (64-bit binary)
• Vendor ID plus product ID plus serial number (ASCII)

The overall WWID consists of the WWID data prefixed by a binary WWID header, which is a longword describing the length and type of WWID data.

In general, if a device reports an IEEE WWID, OpenVMS chooses this as the unique identifying WWID for the device. If the device does not report such a WWID, then the ASCII WWID is used. If the device reports neither an IEEE WWID nor serial number information, then OpenVMS does not configure the device. During the device discovery process, OpenVMS rejects the device with the following message:

%SYSMAN-E-NOWWID, error for device Product-ID, no valid WWID found.

The WWID structures can be a mix of binary and ASCII data. These formats are displayable and are intended to be consistent with those defined by the console WWIDMGR utility. Refer to the Wwidmgr Users' Manual for additional information. (The Wwidmgr Users' Manual is available in the [.DOC] directory of the Alpha Systems Firmware Update CD-ROM.)

Note that if the data following the WWID header is pure ASCII data, it must be enclosed in double quotation marks.

The displayable format of a 64-bit IEEE WWID consists of an 8-digit hexadecimal number in ASCII (the WWID header), followed by a colon (:) and then the IEEE WWID data. For example:

0C000008:0800-4606-8010-CD3C

The displayable format of an ASCII WWID consists of an 8-digit WWID header, followed by a colon (:) and then the concatenation of the 8-byte vendor ID plus the 16-byte product ID plus the serial number. For example:

04100022:"COMPAQ  DLT8000         JF71209240"

Fibre Channel tape and medium changer devices are configured according to information found in the SYS$SYSTEM:SYS$DEVICES.DAT file. This is an ASCII file consisting of two consecutive records per device, where the two records are in the following form:

[Device $2$devnam]
WWID = displayable_identifier

During autoconfiguration, the Fibre Channel is probed and the WWIDs are fetched for all devices. If the fetched WWID matches an entry in the memory-resident copy of the SYS$DEVICES.DAT file, then the device is configured using the device name that has been paired with that WWID.

As an example, the following portion of SYS$DEVICES.DAT causes the eventual configuration of devices named $2$MGA300 and $2$MGA23:

!
[Device $2$MGA300]
WWID = 04100022:"COMPAQ  DLT8000         JF71209240"
!
[Device $2$mga23]
WWID = 04100022:"DEC     TZ89     (C) DECJL01164302"

Although the file is typically read and written only by OpenVMS utilities, in rare instances you may need to edit the file. You can change only the unit number of the device, as described in Section 7.5.5. The internal syntax rules governing the file are summarized as follows:

• Comment lines (beginning with !) and blank lines are permitted.
• Any white space (or none) can separate [Device from the device name represented by $2$xxx ].
• Failure to supply the $2$ prefix will result in a console warning.

Similarly, on the line containing WWID = , any white space (or none) can appear on either side of the equals sign. All lines must be left-justified, and all lines must be less than 512 characters.

The parsing of this file is not case sensitive, with one important exception: all characters enclosed within double quotation marks are taken literally, so that characters such as spaces and lowercase letters are significant. In the case of ASCII data enclosed by double quotation marks, there must be no space between the colon and the double quotation mark.

Also, if more than one WWID = line follows a single [Device devnam] line, the last WWID = value takes precedence. Normally, however, there is exactly one WWID = line per [Device devnam] line.

Similarly, if two or more [Device devnam] lines specify the same device name but different WWIDs, only the last device name and WWID specified in the file is used.

This file is read at boot time, and it is also read from and written to by the SYSMAN IO FIND_WWID command. If there are additional system-specific copies of the SYS$DEVICES.DAT file, their tape naming records become automatically compatible as a result of running SYSMAN IO FIND_WWID on each system. The SYSMAN IO FIND_WWID command is described in more detail in the following section. The SYS$DEVICES.DAT file may also be modified by the SYSMAN IO CREATE_WWID and REPLACE_WWID commands which are described below.

7.5.3 Management Support for Fibre Channel Tape Devices

The following System Management utility (SYSMAN) commands are provided for managing Fibre Channel tape devices:

• IO FIND_WWID
  Probes all ports on the Fibre Channel and detects all previously undiscovered tapes and medium changers, and assigns a name to each. Displays a list of the devices and their assigned device names, and automatically records this information in the SYS$SYSTEM:SYS$DEVICES.DAT file. Also updates relevant local and clusterwide memory structures. It should be executed clusterwide.
  Use this command prior to running the SYSMAN command IO AUTOCONFIGURE.
  Requires the CMKRNL privilege.
• IO LIST_WWID
  Lists all tape device WWIDs that are not yet configured on Fibre Channel. Use this command prior to running the SYSMAN command IO CREATE_WWID.
  Requires the CMKRNL privilege.
• IO CREATE_WWID
  Enables the user to assign a specific (and previously unused) device name to a specific (and previously unused) WWID from the SYSMAN IO LIST_WWID display. It should be executed clusterwide. The command should then be followed by a clusterwide SYSMAN IO AUTO command to actually configure the device.
  This command offers an alternative to the SYSMAN IO FIND_WWID command, which chooses system-generated device names for the discovered WWIDs. The IO CREATE command should not be used after the IO FIND command as a means of redefining WWID correlations. The device and WWID strings specified in IO CREATE_WWID should not be in use elsewhere in the cluster.
  Requires the CMKRNL privilege.
• IO REPLACE_WWID
  Updates appropriate file and memory data structures in case one tape drive must be physically replaced by another tape drive at the same FC LUN location.
  Requires the CMKRNL privilege.

The following DCL support for Fibre Channel tape devices is available:

• The SHOW DEVICE/FULL command displays the WWID for Fibre Channel tape devices.
• The F$GETDVI lexical function supports the keyword WWID , which returns the Fibre Channel tape device's WWID.

This section lists the steps required to configure a new tape or medium changer on the Fibre Channel.

7.5.4.1 Basic Configuration Steps: Summary

The basic steps for configuring new Fibre Channel tape devices in a cluster are as follows:

1. Power on the new tape device or devices.
2. If you are using the MDR, power cycle the MDR to update MDR mapping information.
   If you are using the NSR, use Visual Manager to update the mapping information as follows:
   • Click on the Mapping submenu. Username is root, password is password.
   • Ensure the Select Map box indicates Indexed mode.
   • Click on the Edit/View box that is next to the Select Map box.
   • This brings up an empty indexed map. Under the Priority option, select Target/Bus Priority and then click on Fill Map. Note that the Target/Bus priority ensures that the controller LUN, also known as the Active Fabric (AF) LUN, is mapped to LUN 0.
   • The new map appears. Close that window, which then returns you to the Mapping submenu.
   • If the NSR has additional FC ports besides FC port 0, click on FC Port 1 and repeat the mapping process for FC Port 1, and any other FC ports.
   • Click on Reboot to make the updates to the maps take effect.
     Further details on the Visual Manager are documented in the hp StorageWorks Network Storage Router M2402 user guide (order number: 269782-004).
3. Run SYSMAN to assign device names and configure the devices:

   $ MC SYSMAN SYSMAN> SET ENVIRONMENT/CLUSTER ! Execute on all nodes SYSMAN> IO FIND_WWID ! Assign names SYSMAN> IO AUTOCONFIGURE/LOG ! Configure devices SYSMAN> EXIT

You need to perform these steps only once for the initial configuration. After any subsequent system reboot, the devices will appear automatically.