Are virtual machines of any real practical use?

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Are virtual machines of any real practical use?

Postby Marrea » Sat Aug 05, 2006 6:24 pm

Although I much prefer Ubuntu, I've been messing around with Kubuntu to see what it's like. Because I wasn't sure whether I'd want to keep it permanently on my computer, I've been trying it out in VMware Player, Vmware Server and Parallels. In none of these could I get it to do much multimedia wise at all. Error message after error message. "No input plugin was found." "No plugin found to handle this resource." "Malformed URL." "Maybe you don't have enough rights for this." "Are you trying to play an encrypted DVD without libdvdcss?" Er, no - I've just installed libdvdcss !!

So I lost patience, created another partition at the end of my drive and installed natively. Shortly after installation had finished, I was up and running watching DVDs, playing CDs, ripping and encoding MP3s.

So are virtual machines of any real use for practical purposes? All they seem to be good for is running through an installation to become familiar with the various stages, getting a rough idea of what a distro looks like and perhaps surfing the net safely from Windows.

At least VMware can play an audio CD. Parallels seems completely incapable of finding the CD drive at all.
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RE: Are virtual machines of any real practical use?

Postby GMorgan » Sat Aug 05, 2006 8:18 pm

I find VMware is useful for installing non native software. The key is to do as little as possible with it. I've had no problems with running Office and a few other apps in VMware but haven't tried anything spectacular yet.

The most media intense thing I got running was MW2 in a Win98 VM.
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RE: Are virtual machines of any real practical use?

Postby super_tux » Sat Aug 05, 2006 10:54 pm

Some of the dedicated servers I use for gameservers web host etc are Xen powered virtual ubuntu environments. I have had some very impressive performance from them and no real issues to speak of.

And from a server leasing point of view, brilliant as I can upgrade my server as and when i need to and the provider just changes a few settings to allow me more hdd space, ram etc.

Sooo maybe Xen is the way forward
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RE: Are virtual machines of any real practical use?

Postby GMorgan » Sat Aug 05, 2006 10:59 pm

The problem with Xen is the need for either a modified kernel or supported virtualisation extensions in the CPU.
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RE: Are virtual machines of any real practical use?

Postby nordle » Sun Aug 06, 2006 3:46 am

Virtual machines ARE extremely useful, but perhaps not for what your using them for.

We use vm's to split blades into server apps running within their own vm, its not the same as running a full distro, but it keeps resources targeted and constrained. In short:
- easy upgrade hardware, just increase the % of resource usage.
- easy upgrade software, have a backup running 1/10 second after live to take over, apply changes to live then switch back.
- limited security risks, any hacked servers can be rebuilt within a few mins rather than few hours.
- hardware resources split more evenly, not wasted.

From a corp pov, xen has been great, for home use, I stick with qemu.
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RE: Are virtual machines of any real practical use?

Postby Rhakios » Sun Aug 06, 2006 8:11 am

Hmm, one of the things I haven't tried with any Linux distros under VMWare or Parallels is playing DVDs. I suppose I'll have to have a look now.
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RE: Are virtual machines of any real practical use?

Postby nelz » Sun Aug 06, 2006 8:56 am

Virtual machines are extremely useful but, like everything else, they are not the best answer for everything. I currently have 26 Linux installation (and two windows) in VMware, there's no way I'd have enough disk space for all those installed for real, plus it would mean constant rebooting to try things in different distros.

I've played a (non-encrypted) DVD in Kaffeine in Ubuntu. It didn't work at first, giving the same errors that Marrea saw. It turned out Kaffeine was configured to use /dev/dvd and Ubuntu didn't set this up. Once I'd created the link, the DVD played fine.
"Insanity: doing the same thing over and over again and expecting different results." (Albert Einstein)
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Postby Marrea » Sun Aug 06, 2006 3:10 pm

It was not having to reboot which attracted me to virtual machines in the first place. But I appreciate they are probably designed mainly for corporate, rather than home, use. It could well be that my DVD problem might be solved by creating a link of some sort, if I knew what that link should be. After all, I installed the various distros from the same DVD drive so the v.m.s obviously had no problem identifying the drive then. So this probably indicates it is Linux not finding the drive, rather than the v.m.

However, every time something doesn’t work as expected in a distro installed as a guest o.s. rather than installed natively, there is an extra element of confusion wondering whether it is a Linux problem or a v.m. problem. As I said, I was having a lot of trouble getting Kubuntu to do what I wanted it to do installed on a v.m. but as soon as it was natively installed everything was OK.

Just for clarification, I am using VMware Player and Parallels on one computer with Windows XP as the host; and VMware Server on a different machine, again with Windows XP as the host. Purely out of interest, I was thinking about downloading the Linux version of VMware Server and trying it out on Ubuntu as the host.

I’m afraid I haven’t got round to trying Xen or Qemu yet. Perhaps I should at least have a go at Qemu.

One thing I find you have to be careful about after installing a few distros on a v.m. and then switching to a native install is to make sure for the latter you don’t inadvertently click on “Erase and format the entire hard disk”. :)
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Postby GMorgan » Sun Aug 06, 2006 6:48 pm

I think the problem is that VMware automatically classes everything as a CD-ROM so Ubuntu doesn't autodetect a DVD so doesn't create a link.

Opening fstab and finding where the CD-ROM is in /dev/ then symlinking it should work.
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Postby nelz » Sun Aug 06, 2006 7:52 pm

Code: Select all
ln -s cdrom /dev/dvd
worked for me.

I think you're right about VMware identifying the drive as a CDROM, that's what it shows up as in the BIOS. So if a distro tries to intelligently guess the drive type and only create suitable links, you won't have a /dev/dvd. This is with the full VMware Workstation, the one with the multi-limb price tag :(
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Postby Marrea » Sun Aug 06, 2006 9:09 pm

Well I thought I might have found the reason shortly after my last post when I started up Zenwalk within Parallels, inserted an audio CD, opened Audacious and clicked on "Play CD". I received an error message "No playable CD found. No CD inserted, or inserted CD is not an audio CD."

I looked at /etc/fstab and the relevant line was
Code: Select all
/dev/hdb   /mnt/cdrom   iso9660   noauto,user,ro    0 0

and
Code: Select all
ls -l /dev/cdrom

returned
Code: Select all
lrwxrwxrwx  1  root  root  3  2006-08-06  18:50  /dev/cdrom -> hdb

In the Parallels Configuration Editor, the CD/DVD-ROM Options were as follows:
Device Status: Enabled and Connect at Startup
Emulation: Use real CD/DVD-ROM
CD/DVD-ROM Drives: D:
Attachment options: Connect to: IDE0:1

However, my DVD drive is the secondary master (rather than the primary slave) so shouldn't these settings be IDE1:0 in Parallels and /dev/hdc in Zenwalk?

I have tried changing the "Connect to" setting in Parallels to IDE1:0 and altered the fstab line to read /dev/hdc instead of /dev/hdb. The output from ls -l /dev/cdrom is now
Code: Select all
lrwxrwxrwx 1 root root 3 2006-08-06 22:37 /dev/cdrom -> hdc

but I still get the same error message about no CD inserted. And this is just an audio CD, not even a DVD.

But next time I have the other computer on (the one with VMware Server) I will try the symlink you suggest, nelz, and see what happens there re playing DVDs
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Re: Are virtual machines of any real practical use?

Postby nelz » Sun Aug 06, 2006 9:45 pm

Marrea wrote:Although I much prefer Ubuntu, I've been messing around with Kubuntu to see what it's like.


As Kubuntu is just Ubuntu with the KDE desktop installed as default instead of GNOME, why not just install the KDE packages on Ubuntu?
"Insanity: doing the same thing over and over again and expecting different results." (Albert Einstein)
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Re: Are virtual machines of any real practical use?

Postby Marrea » Mon Aug 07, 2006 11:58 am

nelz wrote:As Kubuntu is just Ubuntu with the KDE desktop installed as default instead of GNOME, why not just install the KDE packages on Ubuntu?


I could have done I suppose. I wasn't really envisaging using Kubuntu for long though, which is why I kept it completely separate. It's too much like any other KDE based distro in appearance and it doesn't immediately grab me like Ubuntu itself does.

Although KDE has lots of useful features (and I confess I use this desktop exclusively in my favourite distro, SUSE, because it somehow feels "right" there), it does have that Windows look about it. I sometimes think when using Linux it's nice to have a bit more of a change, so that's when I switch over to Ubuntu. I really feel I'm using something different then. :wink:
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RE: Re: Are virtual machines of any real practical use?

Postby nelz » Mon Aug 07, 2006 12:05 pm

I understand what you're saying, but this has little do do with distros. you can run GNOME on SUSE or KDE on Ubuntu, the underlying distro is irrelevant to the desktop.

Or you could use a KDE theme that looks nothing like Windows :)
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Re: RE: Re: Are virtual machines of any real practical use?

Postby Marrea » Mon Aug 07, 2006 12:24 pm

nelz wrote: you can run GNOME on SUSE or KDE on Ubuntu, the underlying distro is irrelevant to the desktop.


Very true, but have you noticed how all the screenshots you see of SUSE show KDE and all the screenshots of Ubuntu (not surprisingly!) show Gnome? So you tend to associate a particular distro with a particular desktop.
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