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Virtual Machine Questions

Posted: Wed Apr 24, 2019 6:49 pm
by johnstrasser
Hi Folks,

The wisdom of this community is amazing; which is probably why I came here to ask this question first...

This coming weekend (27 April) I will finally be converting my systems over to Linux (mint as a daily driver and then experimenting with distros and desktops from there). So I'm finally leaving the MS world; my home since 1985.

I do still have and use some apps which don't play nice on linux or even with Wine, so I'll be using virtual machines just for those programs. My working OS will be on an SSD. Most data like docs will be on mechanical.

a) In your experience, does the (non-running) VM file take up the same amount of storage space as it would if were it sitting in a standalone partition, rather than in a VM?
b) Does the (running) VM take up the same amount of drive space as it would if were it running in a standalone partition, rather than in a VM?
c) Other than load time, will a running VM have a performance boost if it is stored on an SSD vs HDD?

Bonus question...

Any recs on a hardware emulation application? I've got some older tbi files that I've been saving just for this - the computer I had died and I can't reinstall the software because the company went out of business (without releasing an unlock key to bypass the licensing servers :twisted: ). This would let me get *my* data out of a now locked system...Lesson learned - I will never again buy or use any software requiring a hardware dongle or internet verification.

I'm sure I forgot something. So any other advice would be appreciated. Thanks for the help.

Re: Virtual Machine Questions

Posted: Thu Apr 25, 2019 12:57 am
by TeraByte Support(PP)
For a & b, the amount of space used depends on the type of virtual drive you use. If you select an "expanding" type of drive then the space used is the spaced used in the virtual drive (plus just a little bit). If you create the drive and have it allocate all space then it will be as large as the drive size you pick. If you link to a physical drive partition then it will use that space.

For c, while it may depend somewhat on system capabilities, it can absolutely make a difference. I would recommend using an SSD or NVMe (even better), if possible. For VM's you rarely run it's probably not so important, though. Also good to have enough RAM in the host to give the client what it needs to run well.

Re: Virtual Machine Questions

Posted: Sat Apr 27, 2019 4:54 pm
by shawn181
I made the same switch two years ago. Microsoft just getting too creepy, fat, and unreliable, especially the update process.
Linux: Debian, XFCE4, lightdm. I've setup similar on Mint, but have come to trust Debian for long term stability and reliable upgrades.
Hardware: Lenovo T540p, 16GB, Samsung Pro SSD 250GB, Transcend M.2 SSD 250GB. (recently added SanDisk UltraPlus SDXC 64GB)
Two SSD's lets me put my Linux OS on one, and frequently used VMs on the other. I also have a small distro installed to boot off second SSD, which makes it convenient to do full cold backups of SSD 1 or perform maintenance.
Hardware emulation / Hypervisor: KVM / QEMU: has been very reliable and lightweight. I'm maintaining four more KVM/QEMU systems almost entirely via ssh / vnc. They've been very stable. (I've also tried VirtualBox, and recommend you avoid it)
a) / b) running or not, about the same amount of disk as physical machine.
Here's some of my VM's disk usage:
162GB - Windows 7 box running since 2009, with tons of software, (converted from physical when I switched to Debian)
70GB - Windows 10, nearly empty, basically only used when I need to use Windows 10. (clean install)
34GB - Windows 7 - dedicated to Intuit TurboTax, has about 8 years of TurboTax installed. (converted from VMware workstation)
4GB - Debian - basic Debian VM
c) if you plan to use the VM frequently, you'll want it on SSD. Of course if you have a lot of RAM, that will help a lot even if using rotational drives.
Overall system disk usage:
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 487M 132K 486M 1% /boot/efi
/dev/sda2 465M 66M 372M 15% /boot
/dev/mapper/Samsung-root 22G 14G 6.8G 68% /
/dev/mapper/Samsung-home 23G 16G 6.2G 72% /home
/dev/mapper/Samsung-libvirt 156G 112G 38G 76% /var/lib/libvirt-2
/dev/mapper/Transcend-libvirt 217G 162G 44G 79% /var/lib/libvirt

Best of luck!

Re: Virtual Machine Questions

Posted: Tue Apr 30, 2019 10:42 pm
by johnstrasser
Thank you gentlemen. I really appreciate the input.

Getting an SSD (or more) for the VMs looks like it will definitely be in the cards; especially since my cooler master case has an external drive bay - lets me treat them like floppy discs <grin>.

Shawn if you don't mind my asking, is KVM/QEMU that much better than virtualbox? Or were there "issues" with VB?

Thanks again

Re: Virtual Machine Questions

Posted: Thu May 09, 2019 3:02 pm
by shawn181
re: VirtualBox vs KVM/QEMU.

I would recommend VirtualBox for a Windows user who wants a very quick setup for the purpose of demo/testing.
I tried to use VirtualBox on windows to run a simple debian instance. I needed it to start automatically with windows and be available 7x24, which means creating a scheduled task to run the Virtualbox headless command. Problem was having started the VM with CLI, the GUI didn't recognize the VM was running: it showed it stopped.
Even so, it wasn't reliable.

On Linux, I'm not sure why anyone would choose VirtualBox. KVM/QEMU has a GUI: Virtual Machine Manager, and a very well documented and very capable CLI.

Re: Virtual Machine Questions

Posted: Fri May 10, 2019 1:47 pm
by johnstrasser
Thank you Shawn. I appreciate it.