Independent Persistent Vs. Independent Non-Persistent

[Ranjna Aggarwal]

Hi,

  Is there anyone who can explain me Independent Persistent Vs. Independent Non-Persistent.

[Shakaal]

Hi,

Please refer to page 164 of http://www.vmware.com/pdf/vsphere4/r40/vsp_40_admin_guide.pdf

Independent mode, which is unaffected by snapshots

Persistent – The disk operates normally except that changes to the disk are permanent even if the virtual machine is reverted to a snapshot.

Nonpersistent – The disk appears to operate normally, but whenever the virtual machine is powered off or reverted to a snapshot, the contents of the disk return to their original state. All later changes are discarded.

Regards

[Ranjna Aggarwal]

Hi,

  I am getting an issue when i selected the independent Non-Persistent disk type:-

My scenario was i have a VM with windows server 2003 and some folders are created by me after that i rebooted the Virtual machine but changes are still there means whatever the changes i made are not lost. After that i tested  another scenario now after creating a folder i took a snapshot and then after taking the snapshot one more folder is created by me and again i reboot the virtual machine but changes are again not lost then after this i reverted the machine to snapshot then what happens now there is no OS in the Virtual Machine. Any idea about this issue?

[Virtualinfra]

*It is very clear that the changes are discarded only if you power off the VM.* (or shutdown the VM)

Rebooting VM or reseting VM is different from power OFF and shutdown. may be you installed some thing and it needs a reboot and after the reboot if the machine dont have those thing,then there is no use of this feature.

I have worked on Non presistent disk and its great.

Try power OFF or shut down of the VM and see those files wont be there.

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[Ranjna Aggarwal]

Thanks Now i am getting the same results as i power off the vm and then power on or either i am reverting it to snapshot because both the case hard disk is blank now but can you tell me the use of independent Non-Persistent Disk.

[Virtualinfra]

Mostly for the Testing and Training.

For Example.

I have team who do testing on their application, during the testing the server crashes lot of time. So just a power OFF and power ON will provide them the Server immediately with all configuraiton in please. (Yes offcourse snapshot helps, but not a right one to use in this case, because snapshot has to used whenever its necessary, also it take datastore space, with IOPs, slow performance etc)

Also same with Training for example, i will have user for practising their application, create their own user ID, profiles,play around till they do their training they can use it for a period of say 10 days or a month and once after that training, we can make available the same server to other set of users for their training, by just powere OFF and ON, Imagine if you use snapshot for 10 days or 1 month and you just revert how much time its going to take also load on the storage, consistents on the disk etc.

We're running several Windows XP and Windows 2003 server guest VMs in a classroom setting.  After class is over the instructor wants to reset the VMs back to default.  We initially configured the disks as independent, nonpersistent with the idea that the students could reboot the VMs during class and keep all changes made, but a shutdown at the end of class would reset the disks back to the default setup.  This worked well.

[Ranjna Aggarwal]

so that hard disk should be blank without any os in INDEPENDENT NON-PERSISTENT Hard Disk

[Virtualinfra]

It depends how you want.

For Example i want it this way:-

First Create a Normal HDD and install os and install required application. Then shutdown the VM. Go to edit setting and change the disk type to independent and non presistence.

now when ever the VM is powered OFF and ON it will come with the Base OS and app which we installed before converting the disk to independent non presistence.

[Ranjna Aggarwal]

Thanks :smileyhappy:

[Virtualinfra]

Hmm you got it

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[naseer702]

great explanation

thanks

[Virtualinfra]

Simple and good explaination is there in the screen of edit setting of the virtuall machine when you add disk.

Independent Disks are not affected by snapshots.

Persistent - Changes are immediately and permanently written to the disk.

Nonpersistent - Changes to this disk are discarded when you poweroff or restore a snapshot.

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