[OpenIndiana-discuss] retrieve individual files from snapshot of vbox virtual disc

[Nikola M.]

On 12/24/14 10:36 PM, Harry Putnam wrote:
> Build 151_a9
> I have the time slider running on a zfs-fs that covers the area where my
> virtual box guests live.
>
> I need some files from a gentoo linux guest.
>
> I have snaps of the vms OS v-discs.  How to get an individual file out of
> there?
If you installed using Virtualbox/GUI, then your disks images are 
probably inside Virtualbox disk image files, that are just plain image 
files on file system (ZFS POSIX layer).
So you spin up another Virtualbox (boot it from Live CD/DVD .ISO image) 
give it disk image file and mount it.
Then you can transfer files over network (NFS, smbfs, ftp, scp whatever) 
to the host system (VBox also support shared folders with guest OS for 
some types of guest OS.

As already suggested, there is also other way on ZFS, that is using 
(sparse) volumes (one that is filled when needed but reads as having 
more space in it then it does), maybe using together with transparent 
compression, larger volblocksize and sync=disabled.
Those volumes can be used by Virtualbox as aether directly, as a block 
device (one first make .vmdk file that points to it and then use in 
VBox, take care to tinker ) or exported via ISCSI ( and also adding it 
to VBox, this one works reasonably well).
Benefit to using volumes is that they can be seen in host system(OI) as 
block devices (that they are) and exactly directly mounted.
Only problem is if host system actually has support/driver for file 
system of guest OS (ext3.4, other).
Ntfs is supported with FUSE on OI and so on. (I haven't manage to 
directly mount ext on OI)

Beside that, rest of questions should be posted to Virtualbox mailing 
list or support channel.
[Vbox-users], 
https://lists.sourceforge.net/lists/listinfo/vbox-users-community
> Is there any way to get at the files in that vm virtual disc, or do I
> have to make whole new gentoo vm and use the disc as one of that
> guests disc.  That is, copy the snapshotted disc to a directory named
> appropriately. Then create a new vm which uses that disc instead of
> creating a new blank disk.
>
> Has anyone here done something like that?
>
> Before I make a really big mess of things I'd like to hear from
> someone with a bit of experience on something like this?
>
> Maybe there is someway to mount it as loop-back mount on
> openindiana?.  Its formated as linux ext4