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OSX guest to access time machine backups

Posted: 30. Nov 2017, 21:02
by waldorfm
Hello,

I have a Mac Pro 2009 and would like to install MS Windows 7 as the primary OS to use some licensed software that isn't ported to Mac OSX. Using a virtual machine with MS Windows instead doesn't give me the best performance to do video conversions and rendering. So far so good, but I need to access files from several encrypted Time Machine backups, without the need to copy several GB of files to the host system to view the content. Unfortunately there does not seem to exist any Windows solution.

My idea is to install Mac OSX, preferably 10.9, as a VirtualBox guest system in order to mount the Time Machine backups using Keychain. Then, somehow make the mounted volumes available to the Windows host.

Questions: Is 10.9 feasible as a guest OS? I remember from past experience that only OSX server would be able to boot. I'm also reading there are no guest additions for Mac OSX guest systems. Are there any other options available than OSX file sharing to access files from a mounted network volume inside a OSX guest machine?

Thank you for any tips and information!

Re: OSX guest to access time machine backups

Posted: 30. Nov 2017, 21:23
by socratis
waldorfm wrote:Is 10.9 feasible as a guest OS?
Yes. Absolutely. I use a 10.9 guest to build VirtualBox from source actually.
waldorfm wrote:I'm also reading there are no guest additions for Mac OSX guest systems.
Correct. Code contributions are always welcome... ;)
waldorfm wrote:Are there any other options available than OSX file sharing to access files from a mounted network volume inside a OSX guest machine?
No. And for the "mounted" part, read my thoughts below.

But your problem is the following, something that I can't see an easy solution:
waldorfm wrote:Then, somehow make the mounted volumes available to the Windows host.
I'm not sure that this is an option that's at your disposal. Try to share your mounted volumes now that you're still on OSX. I don't think you can share mounted volumes, but I haven't tried it to tell you the truth...

Re: OSX guest to access time machine backups

Posted: 1. Dec 2017, 01:19
by waldorfm
I'm not sure that this is an option that's at your disposal. Try to share your mounted volumes now that you're still on OSX. I don't think you can share mounted volumes, but I haven't tried it to tell you the truth...
That's what I'm currently doing. I have another Mac where I'm mounting the time machine disk images stored on a NAS. Then I simply use OSX file sharing to share these mounted volumes using SMB. This allows me to access the time machine volumes from another computer running Windows. It's haves the performance of course going form NAS to Mac and re-share to Windows and it is not a very convenient solution.

Re: OSX guest to access time machine backups

Posted: 1. Dec 2017, 02:01
by socratis
waldorfm wrote:Then, somehow make the mounted volumes available to the Windows host.
waldorfm wrote:That's what I'm currently doing... Then I simply use OSX file sharing to share these mounted volumes using SMB.
Since you already had the recipe worked out, why did you threw me off with that "somehow" ? :)

You can definitely run a 10.9 client in your Windows 7 host, as long as it is running on Apple hardware. I actually tested it two days ago. Host was a Win10 installation running off a USB3 external hard drive on a 2015 MBPr. Not the fastest solution to boot, but once it's up and running, it works as expected.

Since you also have figured how to share your TimeMachine backups using SMB, I believe you're good to go. Just make the 10.9 VM have Bridged networking so that it appears as a peer in the network.

I would start by trying that 10.9 guest in your existing setup. Just setup a new VM and test its functionality before you make the switch. Then you simply move the existing, working VM to your new host, see Moving a VM.

Re: OSX guest to access time machine backups

Posted: 1. Dec 2017, 12:25
by waldorfm
Sorry, I appreciate your help and did not mean to throw you off. Perhaps I should have mentioned that I'm already sharing the mounted time machine volumes from another Mac, but I was looking for another solution to access the data using VirtualBox, other than through the network. Hence my question about the guest additions. But since there are no guest additions, it seems like there's no alternative. So running OSX 10.9 in a VM guest is no problem, which means I do not need to involve another Mac to do the file sharing, but to access the data in the VM guest, I still have to rely the network, which doubles the network traffic.

Re: OSX guest to access time machine backups

Posted: 1. Dec 2017, 13:07
by socratis
waldorfm wrote:but to access the data in the VM guest, I still have to rely the network, which doubles the network traffic.
Well, you could have two adapters in your OSX 10.9 VM; one Bridged which you will use to access the TimeMachine backups over the physical network, and one HostOnly, which you will use to connect from your Win host to your OSX guest. The HostOnly does not go through your physical network, it's a software only solution which will not impact your actual network traffic.

Re: OSX guest to access time machine backups

Posted: 1. Dec 2017, 21:03
by waldorfm
I'll give it a try and report back....

Re: OSX guest to access time machine backups

Posted: 2. Dec 2017, 04:02
by waldorfm
So it works, but the network performance leaves too much to be desired. Here are some test results copying a 3 GB file:

NAS (time machine image) <--100 MB/s --> Mac (mount/share) <--60 MB/s--> Windows
NAS (time machine image) <--25 MB/s --> Windows (OSX guest mount/share)

OSX guest 10.0.0.4 bridged adapter <--17 MB/s--> Windows host
OSX guest 192.168.56.101 host-only adapter <--17 MB/s--> Windows host

Btw, performance accessing a local file between Windows and OSX guest is about 25 MB/s, regardless of bridged or host-only.

I measured the performance in OSX using iostat 1. Using either the bridged or host-only virtual adapter makes no performance difference, at least not under the circumstances. The main problem seems to be the slow network performance of Virtualbox network adapter emulation. I suppose the only way to improve performance would be a virtio*net driver for OSX, but it does not exist.