| Linux version host/guest [message #27785] |
Wed, 27 February 2008 10:57  |
jmelyn
Messages: 27
Registered: June 2007
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Junior Member |
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Hello,
Everything seems to run correctly. But I have a question on the Linux version: It is the same on host and guest.
Host OS (uname -a):
Linux cs-936-dev1 2.6.18-53.1.6.el5.028stab053.6 #1 SMP Mon Feb 11 20:14:31 MSK 2008 x86_64 x86_64 x86_64 GNU/Linux
This is normal.
Guest OS (uname -a):
Linux cs-936-vz01 2.6.18-53.1.6.el5.028stab053.6 #1 SMP Mon Feb 11 20:14:31 MSK 2008 x86_64 x86_64 x86_64 GNU/Linux
This is curious as it is the host kernel.
If I run the command rpm -qa | grep kernel-2 in guest, I have:
kernel-2.6.18-53.1.13.el5
kernel-2.6.18-53.1.4.el5
Is it normal or did I make a mistake while installing?
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| Re: Linux version host/guest [message #27893 is a reply to message #27877] |
Sat, 01 March 2008 10:08  |
jmelyn
Messages: 27
Registered: June 2007
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Junior Member |
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First of all, I want to thank you all spending time to explain things.
As I understand, the guests run the same kernel as their host. I've read that it was possible to run different distros on the same host, but the restriction of the kernel was not clearly written. Now it's simpler: If we need to upgrade the kernel of a guest, we have to upgrade the host and then all the guests will be automatically upgraded. Is that correct? This is another constraint: If we want to upgrade the kernel, we have to wait you (as the OpenVZ developers) make the new ovzkernel package available. Fortunately we use a RHEL5 based distro and last time the package has been out just one month after the official RedHat update.
Some information about what I do:
We need to be able to install, re-install, update or retrieve previous installations in an easy and automatic way because we have many, many servers. At the present moment I have almost finished the scripts of installation, with all our specific stuff. It can be very fast: Less than one minute for a full installation and start of a guest. Installation of a host is now automatic with its guest installations (common and specific stuff); creation of the default cache is done as well. Changing the automatic installation of a guest from one host to another is just changing a sym link. I've not yet made a GUI, but others sys admins are fond of script commands  .
Next steps will be: (1) dynamic management of guest resources, (2) alarms and (3) check-pointing. So you will receive questions from time to time, sometime just stupid...
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| Re: Linux version host/guest [message #27905 is a reply to message #27893] |
Sun, 02 March 2008 04:25 |
ugob
Messages: 271
Registered: March 2007
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Senior Member |
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| jmelyn wrote on Sat, 01 March 2008 05:08 |
First of all, I want to thank you all spending time to explain things.
As I understand, the guests run the same kernel as their host. I've read that it was possible to run different distros on the same host, but the restriction of the kernel was not clearly written. Now it's simpler: If we need to upgrade the kernel of a guest, we have to upgrade the host and then all the guests will be automatically upgraded. Is that correct? This is another constraint: If we want to upgrade the kernel, we have to wait you (as the OpenVZ developers) make the new ovzkernel package available. Fortunately we use a RHEL5 based distro and last time the package has been out just one month after the official RedHat update.
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Yes, you are right. When you update the host's ovzkernel on the host, then reboot, then the hosts will boot in the new kernel, so the guests will also be using this new kernel.
jmelyn wrote on Sat, 01 March 2008 05:08
Some information about what I do:
We need to be able to install, re-install, update or retrieve previous installations in an easy and automatic way because we have many, many servers. At the present moment I have almost finished the scripts of installation, with all our specific stuff. It can be very fast: Less than one minute for a full installation and start of a guest. Installation of a host is now automatic with its guest installations (common and specific stuff); creation of the default cache is done as well. Changing the automatic installation of a guest from one host to another is just changing a sym link. I've not yet made a GUI, but others sys admins are fond of script commands :).
[/quote |
I use vzdump a lot to do that. You can creste some master image then copy and restore them easily.
Next steps will be: (1) dynamic management of guest resources, (2) alarms and (3) check-pointing. So you will receive questions from time to time, sometime just stupid...
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Ok, please read the doc and wiki and hang around on this forum, maybe a lot of answers are already there. See my signature for links.
Please read the manual before asking questions:
http://download.openvz.org/doc/OpenVZ-Users-Guide.pdf
Please have a look at the wiki before asking questions:
http://wiki.openvz.org/Main_Page
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| Re: Linux version host/guest [message #28219 is a reply to message #27914] |
Tue, 11 March 2008 20:10 |
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dowdle
Messages: 261
Registered: December 2005
Location: Bozeman, Montana
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Senior Member |
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Just to clarify... there is one and only one kernel running period... and that is on the host node. You can install all of the kernels you want inside the containers... but you are never going to be able to run them... as there is only one kernel running. While it may be possible to change what kernel a container reports as running... that's just a cosmetic thing.
To get a better picture, understand that OpenVZ is OS virtualization and not machine virtualization. A container is nothing more than a grouping of processes together... with their own resources and filesystem.
From the host node do "pstree -nup". You'll see a number of init processes and children processes under them. The init process with PID 1 is the real init process for the host node and the other init processes are the init processes for each container.
Please note that a container is the init process and its children processes... and the virtualized resources that the OpenVZ kernel provides to isolate these groups of processes. There is only one kernel running.
If you want, you can delete all kernels from your containers... I imagine the kernel packages are installed because they were needed to satisfy package dependencies by the package manager inside of your container. Normally a container doesn't have a kernel package installed.
--
TYL, Scott Dowdle
Belgrade, Montana, USA
[Updated on: Tue, 11 March 2008 20:13] Report message to a moderator |
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but I have some question:
. I can even put it in the name of the cache!
