Virtual images and qemu
Wojciech Puchar
wojtek at puchar.net
Tue Sep 22 19:28:58 UTC 2015
> Now it is fully working. I switched to virtualbox and chose a nat paravirt network.
anyway FreeBSD 10.2 works fine under qemu - both amd64 and i386. tested.
Anyway i never used qcow2 images, always raw.
> I really hate virtualization but will bear with it anyway.
instead of hate it's better to understand.
Cases where virtualization is useful:
- quick test of operating system (probably your case)
- OS/kernel development - avoids reboot as well as provide freeze and
memory dump.
- when you have to run more than 1 different OS on one machine. For
example: FreeBSD server but needs to run some server software under windows. Run
windows virtual machine on this server with this software in it.
- preparing software disk image for different architecture (often used
be me for FreeBSD/mips, qemu on fast PC runs faster than actual machine
and it's easier).
- recovery of data from disks or disk images
- may be few more.
Cases where it is not useful, or suboptimal:
- running multiple images of same unix system (eg. FreeBSD, linux) on one
computer. Use jails or similar mechanism under other unix-alike.
- magic way to enhance security. No it isn't.
- running windows desktops for terminal systems, one virtual machine per
user. Suboptimal and costly, run multiple users on single windows
computer.
- REALLY lots of other uses just because virtualization is popular.
Virtualbox is MUCH faster, qemu is much more universal. Virtualization
always make performance overhead, and always bigger than authors claim.
Still - it is much better running some software set even with 50% overhead, than buying
separate machine that would be 1% utilized.
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