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On Friday, April 24, 2015 10:23:01 PM lee wrote: |
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> "J. Roeleveld" <joost@××××××××.org> writes: |
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> > On Thursday, April 23, 2015 11:03:53 PM lee wrote: |
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> > Do you have anything that you find insufficiently documented or is too |
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> > difficult? |
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> sure, lots |
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Have you contacted the Xen project with this? |
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> > Containers. |
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> > Chroots don't have much when it comes to isolation. |
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> |
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> What exactly are the issues with containers? Ppl seem to work on them |
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> and to manage to make them more secure over time. |
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Lack of clear documentation on how to use them. All the examples online refer |
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to systemd-only commands. |
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> >> >>Which the "better" tool, or combination of tools is, depends on what |
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> >> >>you |
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> >> >>want to accomplish. You could use containers in a VM, too, or use |
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> >> >>virtualbox along with containers to run the odd VMs that require full |
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> >> >>virtualzation. |
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> >> >> |
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> >> > Virtualbox is nice for a quick test. I wouldn't use it for production. |
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> >> |
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> >> Why not? |
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> > |
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> > Several reasons: |
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> > |
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> > 1) I wouldn't trust a desktop application for a server |
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> |
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> So that's a gut feeling? |
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No, a combination of experience and common sense. |
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A desktop application dies when the desktop dies. |
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> > 2) The overhead from Virtualbox is quite high (still better then VMWare's |
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> > desktop versions though) |
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> |
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> Overhead in which way? I haven't done much with virtualbox yet and |
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> merely found it rather easy to use, very useful and to just work fine. |
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Virtualbox is easy when all you want is to quickly run a VM for a quick test. |
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It isn't designed to run multiple VMs with maximum performance. |
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In my experience I get on average 80% of the performance inside a Virtualbox |
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VM when compared to running them on the machine directly. With Xen, I can get |
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95%. |
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(This is using normal work-loads, lets not talk about 3D inside a VM) |
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> Compared to containers, the overhead xen requires is enormous, |
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Hardly comparable. Containers run inside the same kernel. With Xen, or any |
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other virtualisation technology, you run a full OS. |
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> and it |
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> doesn't give you a stable system to run VMs on because dom0 is already |
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> virtualized itself. |
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Why doesn't it provide a stable system? |
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The dom0 has 1 task and 1 task only: Manage the VMs and resources provided to |
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the VMs. That part can be made extremely stable. |
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My Lab machine (which only runs VMs for testing and development) currently has |
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an uptime of over a year. In that time I've had VMs crashing because of bad |
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code inside the VM. Not noticing any issues there. Neither with stability nor |
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with performance. |
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My only interaction with the dom0 there is the create/destroy/start/stop/... |
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VMs. |
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> I don't know how that compares to virtualbox --- I |
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> didn't have time to look into it and it just worked, allowing me to run |
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> a VM on the fly on the same machine I'm working on without any ado. |
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For that scenario, VirtualBox is quite well suited. I wouldn't run Xen on my |
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desktop or laptop. |
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> That VM was simply a copy of a VM taken from a vmware server, and the |
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> copy could be used without any conversion or anything. |
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Good luck doing that when you installed the VMWare client tools and drivers |
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inside a MS Windows VM. |
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> You can't do |
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> that with xen because you'll be having lots of trouble to convert the |
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> VM, to convert the machine you're working on to xen and to get it to |
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> work, to work around all the problems xen brings about ... Some days |
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> later you might finally have it working --- which is out of the question |
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> because the VM is needed right away. And virtualbox does just that. |
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Look into the pre-configured versions of Xen, like what Citrix offers. |
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I can import VMs from VMWare as well without issue. (Apart from the VMWare |
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client tools as mentioned, but Virtualbox has the same issues) |
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> I was really surprised that virtualbox worked that well. Maybe xen will |
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> get there some time. |
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Xen already is there. |
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Please understand that Xen and Virtualbox have their own usecases: |
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Xen is for dedicated hosts running VMs 24/7 |
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Virtualbox is for testing stuff quickly on a laptop/desktop |
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The only common part is that they both run VMs. |
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-- |
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Joost |
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