Hi Guys.
Hope someone can point me in the right direction. I would like to get into LXC and evaluate its usefulness compared with Linux-VServer. I notice that LXC is in tech preview upstream, however I am at a dead end trying to figure out how to get started.
I cannot find any usertools in the rpm's that ship with CentOS 6. Is this because the tech preview requires me to get the tools outside the standard repo's? Of course I am happy to do that, but at the same time I prefer to use tools that are within the CentOS eco-system where possible.
Any help pointing me to documentation specifically with CentOS/RHEL/otherEL (6) will be greatly appreciated. I have not been able to find anything useful in my efforts so far.
Thank you. Matt.
On 07/11/2011 12:50 PM, Matt Paine wrote:
Hope someone can point me in the right direction. I would like to get into LXC and evaluate its usefulness compared with Linux-VServer. I notice that LXC is in tech preview upstream, however I am at a dead end trying to figure out how to get started.
afaik, LXC was on target for 6.2
- KB
On Mon, 2011-07-18 at 12:32 +0100, Karanbir Singh wrote:
afaik, LXC was on target for 6.2
Can someone please summarise the main differences between KVM (Kernel Virtual Machine) and LXC (Linux Containers) which are similar to BSD jails ?
Can one put KVMs into any quantity of LXCs ?
Do LXCs run only with the main operating system, whereas KVM can run with a guest operating system ?
Puuzzled.
As far as I am aware, KVM uses the cpu hardware to run completely different operating systems independently of the host.
LXC is similar to Linux-VServer, or virtuozzo, where you are always running a base kernel, and can run multiple init's at the same time. Each init (and any processes spawed from that init) are completely isolated, which gives the appearance of a different operating system being run. Note that each container uses the same host kernel, so you cant run software that requires older or newer kernels, or kernels which require specific modules that are not in the host kernel. But you get the benefit that you dont need to switch out entire OS images and/or virtualize hardware, processes are simply scheduled as they would be normally. The only overhead is the extra memory/cpu that the extra processes take up.
I like using linux-vserver as I can access my guests filesystem from my host instance (as its usually just a subdirectory of the main filesystem). I also like it as I can control the networking interfaces from the host with ease, and my firewall is controlled from the host, so I know what traffic is going in/out etc and what ports are open for all ip's on the box, through my firewall rules in the central location. I'm not sure how LXC works this way, as I think they virtualize the networking as well, which is why I'm keen to try it out :)
Take what I say with a grain of salt too :)
Matt.
On 19 July 2011 00:26, Always Learning centos@u6.u22.net wrote:
On Mon, 2011-07-18 at 12:32 +0100, Karanbir Singh wrote:
afaik, LXC was on target for 6.2
Can someone please summarise the main differences between KVM (Kernel Virtual Machine) and LXC (Linux Containers) which are similar to BSD jails ?
Can one put KVMs into any quantity of LXCs ?
Do LXCs run only with the main operating system, whereas KVM can run with a guest operating system ?
Puuzzled.
-- With best regards,
Paul. England, EU.
CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
On Tue, 2011-07-19 at 08:22 +1000, Matt Paine wrote:
As far as I am aware, KVM uses the cpu hardware to run completely different operating systems independently of the host.
LXC is similar to Linux-VServer, or virtuozzo, where you are always running a base kernel, and can run multiple init's at the same time.
...............
Thank you for your explanation. It is most helpful. To summarise what I think is correct: One can run multiple LXC containers, each containing an identical version of the main host operating system but processes are separate from the others. KVM creates a type of 'container' allowing different host operating systems to run in that container.
Can one run inside a LXC container a KVM ?
Can one run inside a KVM some LXC containers ?
Or is the simultaneous usage on the same machine of LXC and KVM mutually exclusive or incompatible ?
Thank you again.
Always Learning wrote:
On Tue, 2011-07-19 at 08:22 +1000, Matt Paine wrote:
As far as I am aware, KVM uses the cpu hardware to run completely different operating systems independently of the host.
LXC is similar to Linux-VServer, or virtuozzo, where you are always running a base kernel, and can run multiple init's at the same time.
...............
Thank you for your explanation. It is most helpful. To summarise what I think is correct: One can run multiple LXC containers, each containing an identical version of the main host operating system but processes are separate from the others. KVM creates a type of 'container' allowing different host operating systems to run in that container.
Can one run inside a LXC container a KVM ?
Can one run inside a KVM some LXC containers ?
Or is the simultaneous usage on the same machine of LXC and KVM mutually exclusive or incompatible ?
Thank you again.
I have no experience with LXC, but I have been running Linux-Vserver inside KVM container, without any problem. I suppose that it is the same with LXC.
Running KVM inside LXC I haven't tried, but if it is possible I still think it is not such a good idea. Any disturbance in some of the LXCs will make problem to others (e.g. kernel driver crash will reflect on all LXCs and, therefore, all KVMs).
I think that running LXC/Linux-Vserver inside KVM machine is a great tool to "light virtualize" several small servers inside one "large" KVM.
Regards,
Nenad
Hi Paul. See my un-educated comments inline :)
On 19 July 2011 08:59, Always Learning centos@u6.u22.net wrote:
On Tue, 2011-07-19 at 08:22 +1000, Matt Paine wrote:
As far as I am aware, KVM uses the cpu hardware to run completely different operating systems independently of the host.
LXC is similar to Linux-VServer, or virtuozzo, where you are always running a base kernel, and can run multiple init's at the same time.
...............
Thank you for your explanation. It is most helpful. To summarise what I think is correct: One can run multiple LXC containers, each containing an identical version of the main host operating system but processes are separate from the others. KVM creates a type of 'container' allowing different host operating systems to run in that container.
If can try to clarify my understanding, LXC is process isolation. basically the kernel is shared between the containers. (not specifically the entire host operating system, just the kernel).
KVM will need to be explained by someone else, the only understanding I have with this is it relies on virtualisation in the processor to switch between os's. With the benifit being you can run M$Windows if you want to.
There is no way to run windows with LXC.
Can one run inside a LXC container a KVM ?
If the guest container have the correct privileges, then I would assume so. But I would suggest this would be a messy way to do things, and breaks the whole container concept. The processes in the container are ment to be 'contained' yet to get the correct kernel priveleges to do complete KVM switching would be to open up the entire container to the rest of the system (if thats even at all possible, it may not be! The kernel may not provide the correct privileges to do KVM virtualisation within a LXC guest)
Can one run inside a KVM some LXC containers ?
This one I would say definitely. Since you are running a completely new kernel, I cant see a reason why you couldn't provide an LXC kernel to run within a KVM guest. But theres a bit of guessing here as well :)
Or is the simultaneous usage on the same machine of LXC and KVM mutually exclusive or incompatible ?
Thank you again.
-- With best regards,
Paul. England, EU.
CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
On Tue, Jul 19, 2011 at 4:29 AM, Always Learning centos@u6.u22.net wrote:
On Tue, 2011-07-19 at 08:22 +1000, Matt Paine wrote:
As far as I am aware, KVM uses the cpu hardware to run completely different operating systems independently of the host.
LXC is similar to Linux-VServer, or virtuozzo, where you are always running a base kernel, and can run multiple init's at the same time.
...............
Thank you for your explanation. It is most helpful. To summarise what I think is correct: One can run multiple LXC containers, each containing an identical version of the main host operating system but processes are separate from the others. KVM creates a type of 'container' allowing different host operating systems to run in that container.
Can one run inside a LXC container a KVM ?
Can one run inside a KVM some LXC containers ?
Or is the simultaneous usage on the same machine of LXC and KVM mutually exclusive or incompatible ?
It may not be exactly like LXC but you can also have a look a OpenVZ. I have been using it on many servers for years with no problems. It is quite lightweight and easy to use. I think you can run OpenVZ inside KVM as well.
- SZ Quadri
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Always Learning -
Karanbir Singh -
Matt Paine -
Nenad Opsenica -
SZ Quadri