PCI I/O Bypass controller

General description

CHARON-AXP supports PCI I/O bypass controller for accessing to disk images and host physical disks. In this mode a virtual disk controller type is defined automatically by its name.

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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 first available PCI slot. 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.

I/O Bypass controller is is implemented for OpenVMS only.

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Configuration parameters

The KZPBA PCI SCSI adapter emulation has the following configuration parameters:

container

Parameter

container[N]

N (0...63) is I/O Bypass controller device number.

Type Text string

Value

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

Physical disk
- "\\.\PhysicalDrive<X>", where X is 0, 1, …
  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 PKA container[0]="\\.\PhysicalDrive1"
  .
Physical disk by its WWID
- "\\.\PhysicalDrive(DevID=XXX-...-XXXX)"
  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 PKA 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 PKA container[200]="\\.\PhysicalDrive(iScsiTarget=iqn.2008-04:iscsi.charon-target-test1, LUN= 1)"
  
  .
ddd

SCSI device unknown to Windows for direct mapping, for example, a SCSI disk or tape reader

"\\.\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.

Parameter	Description
N	A logical number assigned by host operating system (Microsoft Windows) to logical or host’s physical storage resource such as physical SCSI HBA
X	An internal SCSI bus number (usually 0) on host’s physical SCSI HBA
Y	A SCSI ID of physical SCSI target device attached to host’s physical SCSI HBA
Z	A logical unit number inside physical SCSI target device attached to host’s physical SCSI HBA

Example:

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

.

Floppy drive
- "\\.\A:"
- "\\.\B:"
  Example:
  set PKA container[300]="\\.\A:"
  .
CDROM device
- "\\.\CdRom<X>", where X is 0, 1, …
  Example:
  set PKA container[400]="\\.\CdRom0"
  .
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 PKA 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 PKA container[401]="tru64-v51-system.vdisk"
  .

File representing the tape (tape image)

[<drive>":\"<path-name>"\"]<file-name>".vtape"
The container-file to which an emulated tape drive is mapped is created automatically when the emulator starts, and when the device is accessed from within the guest operating system.

We recommend specifying the full path to the container-file, for example: "C:\MyTapes\backup.vtape"

Example:

set PKA container[500]="E:\Tapes\backup.vtape"

.

How the Emulator Maps Guest-OS Operations to the Virtual Tape Drive

Guest-OS Operation	Emulator Action
Open device for writing	Create a container file if necessary; open for writing and lock the container file
Open device for reading	Create a container file if none exists. open for reading and lock container file
Unload (eject) tape from drive	Close a container file if open and unlock it - this allows copy/move/delete operations on CHARON host

The container file associated with a virtual tape drive can be compared to the tape cartridge used in a physical tape drive. Both store the data written to the tape device by the guest OS.

The size of virtual tape container files is limited only by space available in the emulator host file system.

Prerequisite to the examples below: a virtual tape device has been configured in the CHARON configuration file and it is not in use by the guest OS.

To perform backup:

The tape device may be issued the "unload" command and the container-file moved/deleted to insure proper status
Initialize the tape device using standard guest OS procedure.
Perform backup.
Issue "unload" command to the tape device in the guest OS.
On the emulator host, move the *.vtape container file containing backup data for storage or further backup.

To restore from a backup:

The tape device may be issued the "unload" command to insure proper status.
On the emulator host, move or copy a *.vtape container file containing backup data onto the filename specified in the CHARON configuration file.
Perform restore.
Issue the "unload" command to the tape device in the guest OS.
Delete or move the container file in preparation for the next vtape operation.

CHARON does not support muti-volume backup for tape images. If some mutli-volume set (in form of tape images) has to be restored it is recommended to configure several tape drives in CHARON VM configuration file, assign each tape image to each tape drive and use them in the following way (OpenVMS example):

$ BACKUP MKA100:BACKUP.BCK,MKA200,MKA300,MKA4000/SAVE_SET DKA0:...

.

Other type of drive, for example magneto-optical drive
- "\\.\<N>:"
  Example:
  set PKA container[300]="\\.\Z:"
  .

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

media_type

Parameter

media_type[N]

N is "XXYY" number, where XX = SCSI ID (0..15) and YY = LUN (00..07)

Type Text string

Value

Instructs CHARON VM to use the supplied value as the PRODUCT field in the SCSI INQUIRY data returned to a software running on virtual HP Alpha system in response to SCSI INQUIRY command.

If not specified, CHARON VM attempts to guess the SCSI INQUIRY data based on virtual SCSI device type and underlying container (which is specified in the corresponding container configuration parameter).

Initially is not specified.

Example:

set PKA media_type[0]="HSZ70"

removable

Parameter

removable[N]

N is "XXYY" number, where XX = SCSI ID (0..15) and YY - LUN (00..07)

Type Boolean

Value

When set to "true", the removable configuration parameter instructs CHARON VM to report the corresponding virtual SCSI device 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/tape image located on a host removable device
Mapped to a disk/tape 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 PKA removable[400]=true

Note that virtual SCSI tapes and CD-ROM devices are always reported as removable regardless of the "removable" configuration parameter.

geometry

Parameter

geometry [N]

N is "XXYY" number, where XX = SCSI ID (0..15) and YY - LUN (00..07)

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 <X>”/”<Y>[“/”<Z>][“/”<B>] or <X>”,”<Y>[“,”<Z>][“,”<B>] where:

Parameter	Description
X	The number of sectors per track
Y	The number of tracks per cylinder
Z	The number of cylinders on the unit. If omitted, Z is calculated based on X, Y and the total number of sectors on the unit that reflects the size of the disk storage element. This is an optional parameter.
B	The total size of the disk (in blocks) reported to the guest OS. If omitted it is calculated automatically. This is an optional parameter.

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

Initially not set.

It is possiblle to specify each parameter independently of another one. The following syntax is used for that:

set PKA geometry[300]="*,*,*,16777210"

The syntax described above is applicable only to disk storage elements. If the container is a tape image, the following format is used instead:

Syntax:

"<image-size>[, <early-warning-zone-size>]"

where:

Parameter

Description

image-size

The tape size in MB

early-warning-zone-size

The size (in KB) of the space left on the tape when a warning to the OS is issued.

If omitted, 64K is assumed.

Example:

set PKA geometry[603] = "255/255"

use_io_file_buffering

Parameter

use_io_file_buffering[N]

N is "XXYY" number, where XX = SCSI ID (0..15) and YY = LUN (00..07)

Type Text 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

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 PKA use_io_file_buffering[603]=true

When a tape or disk image connected to an emulated KZPBA 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. 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 and Tru64 version.

The virtual KZPBA storage controller examines the file extension (vdisk or vtape) to distinguish between a disk image and a tape image.

Configured physical devices or tape/disk images that do not exist on the host system will, in general, cause OpenVMS/Alpha to report the unit offline. In some cases this will result in a VMS BUG CHECK. In this case, an error message will be written to the log file.

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