Booting StreamOptimized VMDK

[vigneshrams]

Hi,

Will i be able to boot stream optimized VMDK child disk in Virtual Box. I was able to boot stream optimized base image vmdk but but attaching the child failed to boot. Any help on this.

/Thanks

[mpack]

What's a "child disk", since you evidently do not mean a differenced disk ?

No, you can't boot compressed VMDKs. You can try cloning it first, ideally selecting "--format VDI", as that will definitely produce a supported format. Though I'm not entirely certain that "VBoxManage clonehd" supports compressed VMDKs as input either.

You don't mention it, but "Stream Optimized VMDKs" are normally only seen as part of a so-called downloadable appliance - OVF or OVA, import of which is supported by VBox.

[michaln]

No, you can't boot compressed VMDKs.

Wrong. Try it.

[vigneshrams]

HI,

Thanks a lot michaln and mpack.

Actually i tried booting Stream_optimized [compressed] parent [full] vmdk file in Virtual box and it booted successfully. Then i tried attaching the first child [ differencing/incremental] but it failed booting with Fatal error message. Is it expected behaviour ? If i am doing something wrong here?

Please shed some light on this.

/Thanks

[mpack]

No, you can't boot compressed VMDKs.

Wrong. Try it.

How can you modify a compressed disk without incurring an enormous overhead? What do you do - automatically treat it as immutable?

[mpack]

Then i tried attaching the first child [ differencing/incremental] but it failed booting with Fatal error message. Is it expected behaviour ? If i am doing something wrong here?

What was the precise error message?

We'll wait to see what Michal says, but if it treats the disk as immutable then it will already have a child attached, which will cause problems if you try to attach another. However if you can get all three partial images registered then you can probably clone the disk as I mentioned earlier (but you must clone the child image, not the base). Anything else would require expert surgery inside the .vbox file.

[michaln]

How can you modify a compressed disk without incurring an enormous overhead? What do you do - automatically treat it as immutable?

Exactly

[mpack]

How can you modify a compressed disk without incurring an enormous overhead? What do you do - automatically treat it as immutable?

Exactly

When did it start doing that? I'm pretty sure it didn't used to work, and I don't find any mention of this feature in the manual. In fact the only direct discussion of compressed or stream oriented VMDKs that I can find says :-

VMDK images that come with virtual appliances are typically shipped in a special compressed format that is unsuitable for being used by virtual machines directly, the images will need to be unpacked and copied first, which can take a few minutes.

[michaln]

The manual is not wrong... compressed images are unsuitable for normal use. Because the image can't be updated, host disk usage will go up. So directly using stream-optimized VMDKs is not something we would recommend.

I don't know when the current behavior was introduced. It's been a while.

[vigneshrams]

Hi,

Thanks for the info.

Error message i get is "Fatal error : no bootable medium found! system halted". This happen when i try booting a incremental VMDK file. But the base/full VMDK boots successfully.


/Thanks

[mpack]

That doesn't sound like the "child" image is related at all. It sounds like a stand-alone non-bootable disk. Why do you think otherwise?

A difference disk works like an overlay on the base disk. If the base disk is bootable then base+child should be bootable as well, except in the very unlikely event that the boot sectors have been zapped on the child - it which case you might as well consider the child disk lost.

Where did you get this child disk from anyway? It wouldn't have been part of whatever OVA you took the base disk from.

[vigneshrams]

Hi,

Thanks a lot.

This child vmdk was created by me using VDDK api. And it has operating system inside it. Windows -7 X64 bit is the OS.

I am attaching a sample base and child disk for your reference. This is not OS volume it is a small data volume. i am able to access the files in full.vmdk whereas the incr1.vmdk fails.

Please check this. https://www.dropbox.com/sh/2nymvsezl9clnpg/yY4QC8Tzgz

/Thanks

[mpack]

I don't normally agree to download unknown files, but ok...

The "incrX.vmdk" files you provide in that dropbox are not child disks, they are completely stand alone. They are also not initialized hence why you can't read from them. If you did initialize them they would read as blank. They certainly do not have an operating system installed inside them, they are not even partitioned, so if you tried to boot from them you'd get what you got: no bootable media found.

I'm not sure what the "VDDK api" is, but creating an additional disk and attaching it to a VM does not make the new disk a differencing image, it simply adds a 2nd drive to the VM.

What is it you are trying to do with these additional disks?

[ChipMcK]

VDDK api ===> Virtual Disk Development Kit (VDDK) api -- by VMWare

[vigneshrams]

Hi MPack,

As i mentioned in the previous thread, the vmdk files i send you will not boot as it is just a DATA volume. Sending a boot volume cant be done considering its size so i send a Stream optimized vmdk with data volume.

And can you please tell me how did you verify that incrX.vmdk are not child disk? Both the parent and child vmdk files are created using VDDK api given by vmware. And able to use those images with vmware-vdiskmanager.exe which is also VMWare tool.


/Thanks