Converting raw partition to image file.

[kentronix]

Hi folks, thank you so much for the information I have already gained from this excellent forum.

A quick question.

I was using the raw partition method to run a guest inside my host. I have decided I would like to convert that partition to a file and use that instead. I have used the virtual media manager to copy the partition (in fact the entire drive) to a file. Which runs fine. Just one question. Does this file reference the original partition in any way ? Can the OS in that image file (when run as a guest) see the original physical partition at all ?

The reason I ask is this machine is a very delicately balanced beast and I dont want to wipe the physical partitions until I am 100% sure the image files are complete and totally standalone.






Some more information because I know people will want to know but I know its not to be discussed so its just by way of understanding my system. If this end part is not allowed or promotes the wrong kind of discussion I will edit it.

Its a browser testing machine. For testing my code in a range of supported browsers.
Its an iMac, which runs Windows 7 native, and OSX snow leopard. OSX was native (dual boot) and I am now running it virtually while inside windows 7 as a raw partition. I intend to switch to an image file. I am sure this is fully within the EULA. I am removing the physical partitions to comply with the "1 install per machine". I dont have any other macs to try this image with. In case your wondering why be so cruel to a mac the win7 pro install has multiple snapshots of xp with various IE versions running in it. Without rebooting I have all the browsers I need.

[mpack]

Does this file reference the original partition in any way ?

Does cloning a "raw access" drive create another raw access drive? Good question, I don't use raw drives so I can't be really sure, but I would think not: the clone would be a standard virtual drive. In fact if the clone is in VDI format (recommended) then you can be absolutely sure that it doesn't reference the physical drive, because VDI does not support that feature.

[kentronix]

excellent, thanks for your reply.

Yes, creating the copy of a raw partition does create a VDI (well a choice is given but thats the option I took).

What I was slightly worried about is that the os running as guest may have access to the system outside of the vbox environment. I think I was worried because it all seems to work a little too well

Thanks for setting my mind at rest. I will report back just in case anyone else is odd enough to try the same thing.

[Perryg]

I have a drive (not a partition) that I use as RAW to do testing in, small 160GB. I was able to copy it via the media manager and it creates a VDI file of 160GB (even though I selected dynamic) and it works as well as the HDD one.

One thing though. I do not have the drive mounted in the Linux host. I see this as a real issue.
I would look at the size of the partition and the size of the VDI file and see if they are close to the same size.

Since I don't have the extra drive mounted the host would not be able to use it unless I defined it via the vmdk file. That said it should be easy enough to test by changing the folder name where the RAW vmdk file is and see if the copied version (.VDI) still works. Be careful though and do not try to access the RAW version while the name is changed. And since this is an important resource for you be sure to make a full backup should things go south.

One last thing, the warning! RAW access is not a thing to play with. Data corruption will ensue if things are changed and the partition information changes for any reason and you fail to update the vmdk file.

[mpack]

it creates a VDI file of 160GB (even though I selected dynamic)

The cloned drive will have been dynamic, but with the block table fully populated. From the pov of VBoxManage, all of the blocks of a fixed size source image (a raw source image counts!) are populated, so it can only discard them if they are all zeros. So, to get compaction you would have to run sdelete/zerofree first. Or use CloneVDI instead.

[Perryg]

I thought that as well, but the actual drive is partitioned into two with the last one not even having a format yet.
That kind of throws off zeroing that partition. It looks like it just copies all of the information sector by sector.

RAW-Clone-HDD.png (126.11 KiB) Viewed 4811 times

Here is the HD info

Code: Select all

perry@perry-desktop:~$ VBoxManage showhdinfo /drive/tara1/VirtualBox-VMs/raw-clone/Ubuntu-12.04-RAW-clone.vdi
UUID:                 a2d1dd09-51bb-499b-be81-6a3ef3b745ab
Accessible:           yes
Logical size:         152628 MBytes
Current size on disk: 143116 MBytes
Type:                 normal (base)
Storage format:       VDI
Format variant:       dynamic default
In use by VMs:        Test-RAW (UUID: 47636eb4-37a9-454a-bcb5-9183a46376c9)
Location:             /drive/tara1/VirtualBox-VMs/raw-clone/Ubuntu-12.04-RAW-clone.vdi

I plan to try to clone this one with CloneVDI with compact and see how it survives.

[Perryg]

Yup works like a champ. I really Love CloneVDI and have since it came out. Lots easier to use than the long way and I can do other things while the tool takes care of the mundane stuff.

RAW-CloneVDI.png (33.87 KiB) Viewed 4802 times

[kentronix]

Mine wouldnt work at all unless I selected dynamic, it may have been a filesize issue though. When I did it dynamic it worked and produced a file of 60gb (drive is 250gb), I estimate about 60gb of that hard drive is actual data so it seems to be ok.

I have been running a few weeks on the raw partition as a virtual machine and its been fine, in fact better than fine. I just really like the ability to backup and also create a differencing image. Which is why the switch to VDI.




For peoples info I have now deleted the original partition and redistributed the space. Copied the image of that said partition over and its running fine from within virtualbox on windows7. Excellent news.

Now I just need to work out how to remove the unwanted partitions that are taking up space inside my images. Gparted wont boot properly in the virtual boxes and disk utility cant do it for some reason. Still, its working so thats the main thing.

[mpack]

Gparted wont boot properly in the virtual boxes

It sure will! People around here use it all time. Make sure to download the official live CD ".ISO", and mount that in your VM. Make sure your VM settings allows boot from CD, and comes before boot from hdd.

[mpack]

I thought that as well, but the actual drive is partitioned into two with the last one not even having a format yet.
That kind of throws off zeroing that partition. It looks like it just copies all of the information sector by sector.

Nasty. In all honesty I must admit that CloneVDI would have a problem with that too. If the partition contains a recognized filesystem then compaction will work. Likewise if the disk space is unpartitioned because CloneVDI can infer that the space is unused. However an unformatted partition is the same as a partition containing an unrecognized filesystem - it will be left alone. You would only get compaction there if the partition data just so happened to be filled with zeros.

[ Edit ] And if the latter was filled with zeros, and VBoxManage didn't discard them, then that's an interesting tidbit of how VBoxManage manages cloning of a raw source.

[Perryg]

I think it has to do with the Copy command within the media manager. I did not use the clone feature which is not in the media manager (at least in my version) I do this on my build which the version is in the future. I need to actually find the code to be sure but it sure looks like a DD to me. If my speculation is correct it would make P2V a lot easier as long as you have access to the physical disk from the host.

[mpack]

I did not use the clone feature which is not in the media manager (at least in my version)

Hmm. It isn't in my version either (v4.1.6 win standard build). Strange. I could have sworn that the word "Clone" used to appear in two places in the GUI: once if you right clicked a VM name, offering to copy a VM, the other was in media manager to copy a virtual disk. No matter, when it comes to the media manager, clone and copy are the same I think.