PCI I/O Bypass controller

Owned by Kirill Nikolaev (Unlicensed)
Last updated: Sept 30, 2021 by Bruno Miretti (Deactivated)Version comment
5 min read

Table of Contents

General description

CHARON-AXP supports PCI I/O bypass controller for accessing to disk images and host physical disks. PCI I/O bypass controller requires a specific driver to be installed.

PCI I/O bypass controller support is available only for OpenVMS guest operating system.

Prerequisites

This release supports VMS version V6.2-1H3 and higher. Bypass disks can not be used as a boot device in V6.2-1H3, higher versions do not have this restriction.

Make sure that the latest Bypass controller kit has been installed, especially for VMS versions before V7.3-2.



Installation

  1. Open CHARON-AXP configuration file and attach the virtual disk "ovms_tool.vdisk"  located by default in the "/opt/charon/disks" directory:

    set PKA container[400] = "/opt/charon/disks/ovms_tools.vdisk"
  2. Run CHARON, boot guest OpenVMS operating system.
  3. Mount the disk, its label is "TOOLS" (Example: $ MOUNT DKA400: TOOLS)

  4. Use the POLYCENTER Software Installation (PCSI) utility to install the Bypass Driver.  The following example demonstrates the "PCSI PRODUCT INSTALL" command to execute and the expected output (the example assumes the utilities virtual disk image is attached as DKA400:):

    $ PRODUCT INSTALL CHARON_DISK/SOURCE=DKA400:[BYPASS]
    %PCSI-I-CANNOTVAL, cannot validate DKA400:[BYPASS]SRI-AXPVMS-CHARON_DISK-V0104--1.PCSI;1
    -PCSI-I-NOTSIGNED, product kit is not signed and therefore has no manifest file
     
    The following product has been selected:
        SRI AXPVMS CHARON_DISK V1.4 Layered Product
     
    Do you want to continue? [YES] YES
     
    Configuration phase starting ...
     
    You will be asked to choose options, if any, for each selected product and for any products that may be installed to satisfy software dependency requirements.
     
    SRI AXPVMS CHARON_DISK V1.4: Charon disk driver V1.4 for OpenVMS Alpha.
     
        Copyright (C) 1976, 2009 Software Resources International
     
        CHARON_DISK was produced by Software Resources International
     
    * This product does not have any configuration options.
     
    Execution phase starting ...
     
    The following product will be installed to destination:
        SRI AXPVMS CHARON_DISK V1.4 DISK$TARDISSYSTEM:[VMS$COMMON.]
     
    Portion done: 0%...10%...20%...80%...100%
     
    The following product has been installed:
        SRI AXPVMS CHARON_DISK V1.4 Layered Product

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Loading PCI I/O bypass controller

Syntax for loading PCI I/O bypass storage adapter:

load pci_io_bypass <name>

The <name> can be DI<x>, DR<x> or DU<x>

where x is selected according to VMS naming scheme, i.e. A stands for the first controller of given type, B - for the second, etc.

Example:

load pci_io_bypass DIA


In AlphaStation 400 configuration use the following syntax for PCI I/O bypass storage adapter loading:

load pci_io_bypass DIA irq_bus=isa

The adapter instance name ("DIA" in the example above) is used then for parametrization, for example:

set DIA container[0]="/Mydisks/vms_distributive.vdisk"

The numbers in the square brackets represent a number of device on PCI I/O Bypass controller.

The maximum number of I/O Bypass controller devices is 64.

By default I/O Bypass controller uses PCI slot corresponded to the <x> parameter (see above). If instead some particular slot is needed, refer to this section for details of specific placement of PCI peripherals on CHARON Virtual Machine (VM) PCI bus (note that "irq_bus" and "irq" parameters are ignored for I/O Bypass controller). In this case the <x> will be changed automatically according to custom position of I/O Bypass controller on PCI bus.

(info) I/O Bypass controller is implemented for OpenVMS only.

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Configuration parameters

The I/O Bypass controller has the following configuration parameters:

container

Parameter

container[N]

N is 0..32766 (no more than 64 units)

Type

Text String

Value

Possible values of the parameter are strings in one of the following forms:

  • Physical disk
    • "/dev/sd<L>" where "L" is letter.
    • "/dev/disk/by-id/..." - addressing by the disk ID, for example "/dev/disk/by-id/ata-ST1000DM003-9YN162_S1D01QJ4"
    • "/dev/disk/by-label/..." - addressing by the disk label, for example "/dev/disk/by-label/MyStorage"

    • "/dev/disk/by-uuid/..." - addressing by the disk UUID, for example "/dev/disk/by-uuid/0e808a2f-cdd3-4944-a245-f729ffd73882"
      (warning) Be careful not to destroy all the information from the disk dedicated to CHARON-AXP by mistake.

      "/dev/sd<L>" addressing is not persistent, so it is strongly recommended to use "/dev/disk/by-id/wwn-*" syntax instead to refer the disk by its WWID - especially in the enviroments utilizing FC and SAN storages.

       These disks must not be formatted by the host OS.

      Example:

      set DIA container[0]="/dev/sdb"

      It is also possible to use not a whole disk, but previously created partitions on it. In this case the syntax is the following: "/dev/sd<L><N>" where N is the number of partition to be used. 

      Example:

      set DIA container[0]="/dev/sdc1".

  • Multipath disk
    • "/dev/dm-<N>" 
    • "/dev/mapper/mpath<N>" 
    • "/dev/mapper/disk<N>" 
      (warning) Be careful not to destroy all the information from the disk dedicated to CHARON-AXP by mistake.  

      These disks must not be formatted by the host OS.

      Example:

      set DIA container[100]="/dev/dm-0"

  • Loop (virtual block) devices

    • "/dev/loop<N>"
      Example:
      set DIA container[200]="/dev/loop0"

  • Direct mapping to some SCSI disks

    • "/dev/sg<N>"
      Example:
      set DIA container[300]="/dev/sg0"

  • File representing a physical disk of the HP Alpha system (disk image)
    • [<drive>":\"<path-name>"\"]<file-name>[".vdisk"]
      These files can be created from scratch with "mkdskcmd" utility. Data and OS disk backups are transferred from the original system via tapes or network and restored into these container files.   

      Mapping may also include the full path, for example: "/my_disks/my_boot_disk.vdisk"

      Example:

      set DIA container[401]="my_dka401.vdisk"

This parameter is initially not set, thus creating NO storage elements on the controller.


removable

Parameter

removable[N]

N is 0..32766 (no more than 64 units)

TypeBoolean
Value

When set to "true", the removable configuration parameter instructs CHARON-AXP to report the corresponding virtual SCSI device as removable.

By default the removable configuration parameter is set to "false".

Example:

set DIA removable[400]=true

geometry

Parameter

geometry[N]

N is 0..32766 (no more than 64 units)

Type

Text String

Value

This formatted string value specifies the explicit geometry of the disk storage element. This parameter is not applicable to tape storage elements.

The string format is ”*/*/*/<B>" or ”*,*,*<B>" where B is the total size of the disk (in blocks) reported to the guest OS. If omitted it is calculated automatically.

If this parameter is not set, CHARON VM will configure the geometry based on the most probable disk type.

Initially not set.

use_io_file_buffering

Parameter

use_io_file_buffering[N]

N is 0..32766 (no more than 64 units)

TypeBoolean
Value

When set to "true", instructs CHARON-AXP to enable host operating system I/O cache on reading/writing operations.

(info) Note that this caching has a significant effect only in case of mapping to disk and tape containers, not physcial drives. 

When enabled, host operating system I/O cache may significantly improve I/O performance of the virtual system. At the same time maintaining I/O cache requires additional host resources (CPU and memory) which may negatively affect overall performance of the virtual system.

Initially is set to "false".

Example:

set DIA use_io_file_buffering[603]=true


When a disk image connected to an I/O Bypass controller is dismounted by OpenVMS, it is disconnected from CHARON-AXP and can be manipulated. It can be replaced with a different disk image if it keeps the same name. This capability may be useful when designing back-up and restore procedures. When copying CHARON-AXP disk images while CHARON-AXP is running, please take care to minimize the risk of overloading a heavily loaded CHARON-AXP host system. For example, using a sequential series of simple ftp binary copies is less resource intensive and thus less disruptive than multiple, simultaneous copies.

Empty disk images are created with the "mkdskcmd" utility. Tape images ("*.vtape") will be created automatically if they don't exist (no utility needed).

CHARON-AXP is able to boot from disk images of any OpenVMS/Alpha version.

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Usage example

Example using DR disk devices (disk drives connected to a SWXCR raid controller):

load pci_io_bypass DRA
set DRA container[1] = "/Mydisks/dra1.vdisk"
set DRA container[2] = "/Mydisks/dra2.vdisk"
set DRA container[3] = "/Mydisks/dra3.vdisk"
set DRA container[4] = "/Mydisks/dra4.vdisk"

Deinstallation

  1. Do a conversational boot. Please refer to your OpenVMS system administration guide for instructions.
  2. Set the NOAUTOCONFIG system parameter to 1
  3. Boot OpenVMS
  4. Remove the product with the "$ PRODUCT REMOVE CHARON_DISK" command.
  5. Set the NOAUTOCONFIG system parameter to 0 and reboot.   


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