Instalation using VirtualBox

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Joined: Mon Oct 22, 2012 5:10 pm

Instalation using VirtualBox

Postby genel » Mon Nov 12, 2012 9:28 am

I posted a while back about my intended system, that description is here: introduction. I have been working with this for a while now and I have to say I am unhappy with my choice of VirtualBox. I chose VirtualBox because I was familiar with it and I thought that would lead to having the system up as quickly as possible.

Well, that has not happened because of one specific problem. I wanted to use raw disks so that, if need be, I could remove a drive, mount on any Linux system and recover the files. I tested this and it all seemed to work, even the recovery part. So I mounted one of the 2TB disks and moved all the stuff to it over the network. (Nothing fancy here, I copied the files to my new shares and let greyhole manage them as he saw fit). All was well, I shutdown the system and installed the second (now empty) 2TB disk. The virtual machine would not reboot; it continued to produce I/O errors during boot. (Disk timeout errors, I don't have the actual message handy at the moment). A web search turned up the possibility of a bad cable. After jiggling cables and a few reboots, the system came up and I thought I had the problem solved. NOT SO, the next time I rebooted the same thing happened. After much experimenting, and web searching, I have come to the conclusion that raw disks do not work well with Virtual Box and Ubuntu. Virtual Box's web site describes similar problems (not exactly) and blame them on Ubuntu. Whatever.

So, I have converted the disks to be VDI images. This seems to work and the system seems to boot without problems.

Each time I thought I had the problem resolved I would move more data to the new system. I also got a deal on a couple more 2 TB drives. Now I have consolidated most of the data that was on three different computers on this system. So each time I made a configuration change there is more and more data to move around.

Greyhole has been a champion during this process, moving data around, recovering migrated files, making extra copies, deleting excessive copies. So far it has not disappointed.

The problem now is performance. It sucks. If I copy a large file (a DVD image) to the base system (the virtual host) the transfer is at about 115 MB/s. If I transfer it to the Amahi server running in the virtual box, the rate is about 45 MB/s. I expected some penalty for the virtual machine, but that's about about 1/3 the speed. When I can get a raw disk up and running on the VM the performance is the same, so it's not the double file system overhead that I was afraid of when I decided to use VDIs instead of raw disk access.

If anyone else has tried VirtualBox I would like to know if your experience matches mine, particularly as far as performance goes.

If you are using some other hypervisor can you tell me about your performance testing?

Can someone recommend a good benchmark to test network and disk throughput so I can get some idea of where my problems lie?

At this point, I could not recommend my configuration to anyone, the overhead of using VirtualBox is too high and the problems with raw disks removes an important aspect of the system design.

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Re: Instalation using VirtualBox

Postby sgtfoo » Mon Nov 12, 2012 2:06 pm

I've tried with both Proxmox and ESXi5 and my transfer speeds are akin to having a hardware Amahi box.. between 50 and 70 MB/s transfer via shares seen in Windows 7. Very many things weigh into transfer speeds. We have a long thread about it worth searching for.
CPU speed, network speed (cabling and routers/switches), interfaces and drive types all weigh in heavy on the rate of transfer. I've never breached 85MB/s in a transfer no matter what, so there's overhead or drive limitations somewhere.

In either hypervisor, SATA drives can be mounted directly to a VM, so I have done just that with 2 drives and let greyhole use them both. For the OS volume I use a drive image (raw) and it resides on LVM space that Proxmox provides for such images so that it can be expanded if need be.
HDA: VM inside oVirt FX-8300 95w (2 cores for HDA), 32GB RAM (2GB for HDA)
My PC: FX-8300, 16GB RAM, 3x 1TB HDDs, Radeon HD6970 2GB video; Win10 Pro x64
Other: PC, Asus 1215n (LXLE), Debian openZFS server (3x(2x2tb) mirrors)
Modem&Network: Thomson DCM475; Asus RT-AC66U; HP 1800-24G switch

Posts: 41
Joined: Mon Oct 22, 2012 5:10 pm

Re: Instalation using VirtualBox

Postby genel » Mon Nov 12, 2012 2:51 pm


I will read some more on proxmox. From my reading it appears that "baremetal" hypervisors don't suffer from this problem, but that IO problems are common with software solutions.

Thanks again.

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