ID #1053

SCSI-devices : the parameters

 

In recent virtual hardware you can use up to 60 devices - 15 for each available controller.
So to identify a SCSI-device you use the controller-number 0 - 3 plus the SCSI-ID of the device for that controller 0 - 15. The scsi-ID 7 is reserved for the controller.
The range for devices is
scsi0:0 to scsi3:15

The parameter present again is used as the main-switch - if you set it to false all other sub-parameters will be ignored.

The parameter in details ...

 


 

scsi0:0.present

scsi0:0.present = "TRUE"
the device is enabled

scsi0:0.present = "FALSE"
the device is disabled


 

scsi0:0.deviceType

this parameter defines the type of device used for the specified SCSI-ID.
This parameter can be skipped if a regular vmdk-file is used.
It must be defined if you use anything else. Options are listed below

scsi0:0.deviceType = "disk"
scsi0:0.deviceType = "plainDisk"
scsi0:0.deviceType = "PhysicalDrive0"
scsi0:0.deviceType = "rawDisk"
scsi0:0.deviceType = "scsi-hardDisk"
scsi0:0.deviceType = "scsi-nonpassThru-rdm"
scsi0:0.deviceType = "scsi-passthru"
scsi0:0.deviceType = "scsi-passThru-rdm"
scsi0:0.deviceType = "cdrom-image"
scsi0:0.deviceType = "atapi-cdrom"
scsi0:0.deviceType = "cdrom-raw"

In most cases you should not edit this parameter.
Only exception: troubleshooting CD-rom issues and creating snapshots of physical disks.


 

scsi0:0.fileName

This parameter defines which file or device is used for the specified SCSI-ID.

scsi0:0.fileName = "windows xp.vmdk"
This line is used if the device is a regular vmdk-file.
Absolut and relative paths can be used but it is highly recommended NOT to use absolute paths.

scsi0:0.fileName = "setup.iso"
This line is used if the device is an iso-file.
Absolut and relative paths can be used but it is highly recommended NOT to use absolute paths.

scsi0:0.fileName = "E:"
This line is used to specify a physical CD-drive by a driveletter on a Windows-host

scsi0:0.fileName = "/dev/hdc"
This line is used to specify a physical CD-drive on a Linux host

scsi0:0.fileName = "auto detect"
This line is used to autodetect a physical CD-drive on hosted platforms.
Do not use this - it is unreliable.

 


 

scsi0:0.mode

The usage of this parameter is inconsistent and has been changed with recent versions.
Some older versions used slightly different syntax - handle with care ...
I describe the options available in WS 7 here

This parameter is only used for virtual disks.
It controls how a virtual disk is affected by snapshots
WARNING: don't set this parameter unless you know what you are doing.

scsi0:0.mode = "persistent"
This value is used as the "silent default" - a virtual disk configured in this mode can use snapshots.

scsi0:0.mode = "independent-nonpersistent"
A virtual disk in this mode will create a REDO-log when it is started and destroys it when it is shutdown.
During use all changes go into a file named like the original vmdk plus an added extension  - example:
name.vmdk.REDO_a03896
Practical use: browse the net - catch a virus - enjoy seeing the virus in action killing your system - reset the system.
WARNING: This mode effectively is a global hot snapshot off switch.
As soon a single vmdk of the VM is configured like this you can no longer take  hot snapshot of this VM.
You can still use cold snapshots but this disk will be excluded.
Changes to this virtual disk will be discarded next time the VM is powered off.
Be careful with this switch if you want to use automated backup-tools


scsi0:0.mode = "independent-persistent"
WARNING: This mode effectively is a global hot snapshot off switch.
As soon a single vmdk of the VM is configured like this you can no longer take  hot snapshot of this VM.
You can still use cold snapshots but this disk will be excluded.
Changes to this virtual disk will be directly written to disk.
Be careful with this switch if you want to use automated backup-tools.



scsi0:0.mode = "undoable"
scsi0:0.mode = "nonpersistent"
This modes were used in older versions.
In Workstation 7 they are no longer recognized and will produce error-messages.
Do NOT use this modes unless you know what you are doing.

The undoable mode maybe useful to handle very old  VMs created on GSX 2.5 - see
/index.php?action=artikel&cat=18&id=55
for instructions

 


scsi0:0.writeThrough

This parameter is used for virtual disks only and will be ignored for CDs.

scsi0:0.writeThrough = "TRUE"
scsi0:0.writeThrough= "FALSE"

WARNING: handle with care - behaviour is different on Windows and Linux


 

scsi0:0.shared

This parameter is used for virtual disks only and will be ignored for CDs

scsi0:0.shared = "TRUE"
this virtual disk can be used by more then one VM.

scsi0:0.shared= "FALSE"
This is the silent default and so can be skipped.


scsi0:0.clientDevice

This parameter is used for remote CD-devices on ESX and VMserver and will be ignored by Workstation

scsi0:0.clientDevice = "TRUE"
A CD device from the admin-host will be used

scsi0:0.clientDevice = "FALSE"
This is the silent default and so can be skipped.

 


 

 

scsi0:0.clientDevice

This parameter is used for remote CD-devices on ESX and VMserver and will be ignored by Workstation

scsi0:0.clientDevice = "TRUE"
A CD device from the admin-host will be used

scsi0:0.clientDevice = "FALSE"
This is the silent default and so can be skipped.

 


 

scsi0:0.exclusive

This parameter is used for CD-devices only - it will be ignored with virtual disks.

scsi0:0.exclusive = "TRUE"
only this VM may use this physical CDrom (don't use unless you need to)

scsi0:0.exclusive = "FALSE"
this is the silent default and so can be skipped

 


 

scsi0:0.autodetect

This parameter is used for CD-devices only - it will be ignored with virtual disks.

scsi0:0.autodetect = "TRUE"
the host tries to automatically assign a physical - or virtual CD-rom-device.
Don't use this wihen you have daemon-tools or other CD-emulators installed.
Using this is unreliable.

scsi0:0.autodetect = "FALSE"
this is the silent default and so can be skipped

 


 

scsi0:0.allowGuestConnectionControl

This parameter is used for CD-devices only - it will be ignored with virtual disks.

scsi0:0.allowGuestConnectionControl = "TRUE"
A user inside the VM can connect to a CD using the vmware-toolbox

scsi0:0.allowGuestConnectionControl = "FALSE"
A user inside the VM can NOT connect to a CD using the vmware-toolbox


Tags: scsi, vmx

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Comment of bNLSovPkf:
Thin disk provisioning is cdsiiue for most customers and yields no benefit at all.The benefit of VMFS is that it pre-allocates the whole vmdk file and stores that information in vmkernel while the VM is running. That means vmerkenl does not have to allocate new disk blocks when the vm needs it. This is not the case with thin provisioned disks.I dare anyone to test a high IO SQL server with thin versus thick (default) and see how think provisioned disks outperform.Also, if users over allocate the vmfs (the only real reason to use thin) and the vmfs volume fills up because the user does not monitor the filesystem then you can kiss some of your VMs goodbye.
Added at: 2012-03-04 03:30