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General description

CHARON-AXP supports PCI I/O bypass controller for accessing to disk images and host physical disks.

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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

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

set DIA container[0]="C:\My disks\vms_distribution.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)

TypeText string
Value

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

  • Physical disk

    •  "\\.\PhysicalDrive<X>", where X is 0, 1, … 
      (warning) Be careful not to destroy all the information from the disk dedicated to CHARON VM by mistake. 
      These disks must not be formatted by the host OS. 
      Example:

      set DIA container[0]="\\.\PhysicalDrive1"

      .

  • Physical disk by its WWID 

    • "\\.\PhysicalDrive(DevID=XXX-...-XXXX)"

      (warning) Be careful not to destroy all the information from the disk dedicated to CHARON VM by mistake.

      These disks must not be formatted by the host OS.

      DevID addresses the target physical disk by its WWID (hexadecimal 128-bit identifier assigned to the disk drive by its manufacturer/originator).

      Example:

      set DIA container[100]="\\.\PhysicalDrive(DevID=6008-05F3-0005-2950-BF8E-0B86-A0C7-0001)"

      .

  • iSCSI disks
    • "\\.\PhysicalDrive(iScsiTarget = <iSCSI target>, LUN = <LUN number>)"

      iScsiTarget addresses the disk by its iSCSI target name.

      LUN specifies LUN on connected iSCSI disk.

      Example:

      set DIA container[200]="\\.\PhysicalDrive(iScsiTarget=iqn.2008-04:iscsi.charon-target-test1, LUN= 1)"

      .

  • dddSCSI disk unknown to Windows for direct mapping

    • "\\.\Scsi<N>:<X>:<Y>:<Z>" 
      The values of N, X, Y and Z can be collected using special utility "Host Device Check" included in the CHARON distributive - or manually by investigation of the devices connected to CHARON host in the "Device Manager" applet.

      ParameterDescription
      NA logical number assigned by host operating system (Microsoft Windows) to logical or host’s physical storage resource such as physical SCSI HBA
      XAn internal SCSI bus number (usually 0) on host’s physical SCSI HBA
      YA SCSI ID of physical SCSI target device attached to host’s physical SCSI HBA
      ZA logical unit number inside physical SCSI target device attached to host’s physical SCSI HBA

      Example: 

      set DIA container[202]="\\.\Scsi1:0:1:0"

      .

  • ISO file for reading distribution CD-ROM image
    • [<drive>":\"<path-name>"\"]<file-name>[".iso”]  
      Mapping may also include the full path (recommended), for example: "C:\My disks\vms_distribution.iso"  

      Example:

      set DIA container[600]="C:\My disks\vms_distribution.iso"

      .

  • 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 "MkDisk" utility. Data and OS disks backups are transferred from the original system via tapes or network and restored into these container files.   
      Mapping may also include the full path (recommended), for example: "C:\My disks\my_boot_disk.vdisk"   
      Example: 

      set DIA container[401]="tru64-v51-system.vdisk"

      .

  • Other type of drive, for example magneto-optical drive

    • "\\.\<N>:" 
      Example:

      set DIA container[300]="\\.\Z:"

      .

(info) 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 VM to report the corresponding virtual disk as removable.

Note to set this parameter to "true" if this disk storage element is:

  • Mapped to a host removable device
  • Mapped to a disk image located on a host removable device
  • Mapped to a disk image that has to be renamed/moved/deleted right after dismounting it in the guest OS

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)

TypeText 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)

TypeText String
Value

Instructs CHARON VM to enable host operating system I/O cache on reading/writing operations.

The following values are possible:

  • "true" or "write-back" - the "write back" caching mode is used

  • "write-through" - the "write through" caching mode is used

  • "false" - caching is switched off

(info) Note that this caching has a significant effect only in case of mapping to disk and tape containers, not physical 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 VM 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 VM is running, please take care to minimize the risk of overloading a heavily loaded CHARON 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 "MkDisk" utility.

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

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