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HP OpenVMS Systems Documentation |
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Guidelines for OpenVMS Cluster Configurations
7.5.4.2 Basic Configuration Steps: DetailsPrior to configuring a tape device on Fibre Channel, the worldwide identifier (WWID) of the device must be detected and stored, along with a device name, in the text file SYS$SYSTEM:SYS$DEVICES.DAT. This is usually accomplished by using the SYSMAN command IO FIND_WWID. However, some users prefer to choose their own devices name for the tape devices, rather than using the system-generated names assigned by FIND_WWID. In that case, the user will execute the IO CREATE_WWID command instead of IO FIND_WWID. IO CREATE_WWID will be described in the next section, while this current section documents the use of IO FIND_WWID. The IO FIND_WWID command probes all ports on the Fibre Channel and locates all tape and medium changer devices connected to an MDR or NSR. For tapes and medium changers that have not been detected by a previous IO FIND_WWID command, IO FIND_WWID assigns a device name, retrieves the WWID of the device, stores the device name and WWID data in the SYS$SYSTEM:SYS$DEVICES.DAT file, and updates memory structures. Since the primary goal of IO FIND_WWID is to populate the SYS$DEVICES.DAT file, you need to invoke the IO FIND_WWID command only once for each device. IO FIND_WWID does not configure the $2$MGAnnnn: device for use by an application. Once the information is stored in the file, subsequent use of the IO AUTOCONFIGURE command reads a memory-resident copy of the file and configures the tape and medium changer devices automatically, loading or connecting the device drivers as needed. The SYS$DEVICES.DAT file is read into memory during each system reboot; this action initiates the automatic configuration of tapes and medium changers on the Fibre Channel. Note that running the IO FIND_WWID command for the first time detects all existing tape and medium changer devices on the system. If you add additional Fibre Channel tape devices to the system at a later time, you must first powercycle the MDR to update internal mapping information, and then run the IO FIND_WWID command again to append the new device information to the SYS$DEVICES.DAT file. On an NSR, edit the indexed map to update mapping information. In an OpenVMS Cluster environment, various data structures in memory must be updated on each system when a new Fibre Channel tape device is added. To accomplish this, HP recommends that you run the SYSMAN IO FIND_WWID command on each Alpha node in the cluster. Alternatively, you can run IO FIND_WWID on one node, and then reboot the other nodes that share that same system disk, because the SYS$DEVICES.DAT file is read at boot time and causes memory structures to be correctly initialized. In the case of multiple system disks in the cluster, ensure that all copies of the SYS$DEVICES.DAT file are kept consistent, preferably by running the IO FIND_WWID command on all nodes. Alternatively, you can run IO FIND_WWID to update just one SYS$DEVICES.DAT file, and then manually edit the remaining SYS$DEVICES.DAT files by cutting and pasting the appropriate device name and WWID records from the original file to the target files. If this second alternative is used, however, the remaining nodes must be rebooted in order for the memory-resident copy of SYS$DEVICES.DAT to be updated. HP recommends that you refrain from copying the entire original file to another system disk. The SYS$DEVICES.DAT file is also used to define port allocation classes (PACs), and PAC entries could be transferred inadvertently to the target system. Following is a configuration example using a TL891 tape library on a single node. First, the SYSMAN command IO FIND_WWID displays a list of all previously undiscovered tape devices and their proposed device names.
Note that the overall WWID consists of everything to the right of the equals sign. Each such WWID is unique; however, the header portion may not be unique, because the header reflects only the basic type and length of the the WWID data. The IO FIND_WWID command automatically records the information about the new tape devices in SYS$SYSTEM:SYS$DEVICES.DAT:
Next, the SYSMAN command IO AUTOCONFIGURE configures the tape device.
Finally, the SHOW DEVICE/FULL command displays the WWID of the tape device.
The F$GETDVI lexical function also retrieves the displayable WWID:
Once the device is named and configured, you can use the device in the same way that you use parallel SCSI tapes with DCL commands such as INITIALIZE, MOUNT, BACKUP, and COPY. Refer to the installation guide for individual tape layered products for details on product-specific support of Fibre Channel tapes.
Note that while medium changers on Fibre Channel are autoconfigured,
the medium changers on parallel SCSI continue to require the IO CONNECT
command to load the device driver. It is impossible to manually connect
a Fibre Channel medium changer by the SYSMAN IO CONNECT command because
the device name does not imply the device's physical location, as it
does in parallel SCSI.
The selected name must be of the form $2$GGAn for medium changers and $2$MGAn for tapes, where n is less than or equal to 9999. The name must not be in use elsewhere in the cluster. The WWID should be cut and pasted from the output of the IO LIST_WWID display. The IO CREATE_WWID command is intended only for naming new devices; it should not be used to rename existing devices. (Renaming existing devices is discussed in Section 7.5.5.) The following configuration example uses IO CREATE_WWID to create user-specified device names for two tapes and a medium changer within an ESL library. The commands are excuted clusterwide on a 2-node cluster consisting of nodes SYSTM1 and SYSTM2. Each node has two Fibre Channel host bus adapters, PGA0 and PGB0, so multiple paths to the tape are configured. First, the SYSMAN command IO LIST_WWID displays a list of all previously undiscovered tape devices.
The previous NOMORENODE error is normal, because the command has completed on all existing nodes. Next, still in the same SYSMAN session, the user executes IO CREATE_WWID to choose device names $2$GGA40, $2$MGA40, $2$MGA41.
The user now executes IO AUTOCONFIGURE to configure the devices. Note that both the PGA path and the PGB path are configured for each node.
7.5.5 Changing the Name of an Existing Fibre Channel Tape DeviceBecause SYS$SYSTEM:SYS$DEVICES.DAT is a text file, you can edit it but only to change the unit number of a Fibre Channel tape or medium changer device. However, as stated earlier, Fibre Channel tape and medium changer device information is stored internally by OpenVMS using clusterwide data structures, specifically clusterwide logical names. To clean up these data structures, you must do a complete cluster shutdown. A rolling reboot (leaving at least one node up during the reboot of other nodes) is inadequate to clean up the structures. The specific steps for changing an existing device name follow:
7.5.6 Moving a Physical Tape Device on Fibre Channel
When you move a tape or medium changer device without changing its
name, rebooting is not required. However, you must ensure that the NSR
or MDR has assigned a FC LUN to the device at its new location, and you
must then run SYSMAN IO AUTOCONFIGURE to configure the new physical
path to the device. For changers only, you must also manually switch
the changer to the new path using the SET
DEVICE/SWITCH/PATH=new_path command. The previous paths will
still show up in the SHOW DEV/FULL display, but those paths will be
stale and unused, with no harmful side effects; after the next reboot
the stale paths will disappear.
You can swap out an NSR without rebooting the Alpha OpenVMS system. (This capability was introduced in OpenVMS Alpha Version 7.3-1.) After attaching the new NSR, use the Mapping submenu in the Visual Manager to populate the Indexed map on each Fibre Channel port of the NSR and reboot the NSR. An alternative way to map the new NSR is to copy the .cfg file from the previous NSR via the NSR's FTP utility.
Once the Indexed map is populated, run SYSMAN IO AUTOCONFIGURE to
configure the new physical paths to the tape. For changers only, you
must also manually switch the changer to the new path using the SET
DEVICE/SWITCH/PATH=new_path command. The previous paths will
still show up in the SHOW DEV/FULL display, but those paths will be
stale and unused, with no harmful side effects; after the next reboot
the stale paths will disappear.
In general, all OpenVMS Alpha Version 7.2-2 or later nodes in an OpenVMS Cluster have a direct path to Fibre Channel tape devices if the nodes are connected to the same Fibre Channel fabric as the NSR (or MDR). VAX nodes and Alpha nodes running earlier versions of OpenVMS, as TMSCP clients, can be served Fibre Channel tape devices by an OpenVMS Alpha Version 7.2-2 or later node. To provide this feature, pre-Version 7.3 VAX nodes require the latest update kit for TUDRIVER.EXE, and pre-Version 7.2-2 Alpha nodes require the latest update kit for SYS$TUDRIVER.EXE.
Medium changers, whether connected to Fibre Channel or to parallel
SCSI, cannot be TMSCP served.
If one tape drive must be physically replaced by another tape drive at the same FC LUN location within the MDR or NSR, update the appropriate data structures with the IO REPLACE_WWID command. For example, you may need to replace a defective tape drive with a new drive without rebooting the cluster, and that drive may need to retain the device name of the previous tape at that location. The replacement device should have the same SCSI target ID as the original device. Cease all activity on the device, then type the following command to update all the necessary file and memory data structures with the WWID of the new tape drive:
Execute this command on each Alpha node in the cluster environment. You can accomplish this with the following commands:
In some cases, this command may fail because the device name $2$MGA1 no longer exists in the SHOW DEVICE display. This happens when the system has been rebooted some time after the drive has malfunctioned. In such a case, you must specify both the device name and the WWID, as shown in the following example. The WWID must be the WWID of the new device that resides at the same Port/Target/LUN location as the replaced device. (To determine the value of the WWID that resides at a particular Port/Target/LUN location, use the SYSMAN IO LIST_WWID command.)
7.5.10 Determining the Physical Location of a Fibre Channel Tape DeviceGiven the name of a Fibre Channel tape device, it is helpful to know how to locate the Fibre Channel tape device. To do so, follow these steps:
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