as i'm reviewing the courseware for the rhel (centos) course i'm teaching next week, i'm going to ask the occasional question, possibly technical, possibly more policy.
first one involves the choice for virtualization. the course has a short section involving virt using xen but everything i've read suggests that red hat is concentrating on kvm for virt. thoughts on that? i have the freedom to replace the xen section with one covering kvm instead.
rday
On Mon, 9 Aug 2010, Robert P. J. Day wrote:
as i'm reviewing the courseware for the rhel (centos) course i'm teaching next week, i'm going to ask the occasional question, possibly technical, possibly more policy.
first one involves the choice for virtualization. the course has a short section involving virt using xen but everything i've read suggests that red hat is concentrating on kvm for virt. thoughts on that? i have the freedom to replace the xen section with one covering kvm instead.
KVM feels less intrusive to me, but Xen configuration seemed to have a shorter learning curve.
I don't really need a lot of performance in my VMs, so I can't comment on speed; both do the trick.
Red Hat has done a nice job with virsh and virt-install, which both work as advertised whether you're running Xen or KVM.
My suggestion, fwiw, is to figure out if students are more interested in maintaining an installed base of VMs or in installing a new VM infrastructure. Chances are, maintenance is more Xen-heavy, while KVM is more the way forward for new installations.
RHEL6 will not have xen for hosting. It could be a xen guest. If you are teaching with the concept of having guests under the RHEL host and you want your teachings relevant going forwards you will need to cover kvm.
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On 9 Aug 2010 19:35, "Paul Heinlein" heinlein@madboa.com wrote:
On Mon, 9 Aug 2010, Robert P. J. Day wrote:
as i'm reviewing the courseware for the rhel (centos) course i'm teaching next week, i'm going to ask the occasional question, possibly technical, possibly more policy.
first one involves the choice for virtualization. the course has a short section involving virt using xen but everything i've read suggests that red hat is concentrating on kvm for virt. thoughts on that? i have the freedom to replace the xen section with one covering kvm instead.
KVM feels less intrusive to me, but Xen configuration seemed to have a shorter learning curve.
I don't really need a lot of performance in my VMs, so I can't comment on speed; both do the trick.
Red Hat has done a nice job with virsh and virt-install, which both work as advertised whether you're running Xen or KVM.
My suggestion, fwiw, is to figure out if students are more interested in maintaining an installed base of VMs or in installing a new VM infrastructure. Chances are, maintenance is more Xen-heavy, while KVM is more the way forward for new installations.
-- Paul Heinlein <> heinlein@madboa.com <> http://www.madboa.com/ _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
On 08/09/2010 07:06 PM, Robert P. J. Day wrote:
as i'm reviewing the courseware for the rhel (centos) course i'm teaching next week, i'm going to ask the occasional question, possibly technical, possibly more policy.
how much of this courseware is open source licensed ? Would you be willing to contribute some /all of it towards the CentOS wiki / docs effort ?
- KB
On Mon, 9 Aug 2010, Karanbir Singh wrote:
On 08/09/2010 07:06 PM, Robert P. J. Day wrote:
as i'm reviewing the courseware for the rhel (centos) course i'm teaching next week, i'm going to ask the occasional question, possibly technical, possibly more policy.
how much of this courseware is open source licensed ? Would you be willing to contribute some /all of it towards the CentOS wiki / docs effort ?
sorry, it's not my C/W, it's being licensed for this course.
rday
On 08/09/2010 08:16 PM, Robert P. J. Day wrote:
how much of this courseware is open source licensed ? Would you be willing to contribute some /all of it towards the CentOS wiki / docs effort ?
sorry, it's not my C/W, it's being licensed for this course.
From whom ?
- KB
On Mon, 9 Aug 2010, Karanbir Singh wrote:
On 08/09/2010 08:16 PM, Robert P. J. Day wrote:
how much of this courseware is open source licensed ? Would you be willing to contribute some /all of it towards the CentOS wiki / docs effort ?
sorry, it's not my C/W, it's being licensed for this course.
From whom ?
i don't think there's any issue in admitting that it's courseware from http://onsight.com. i was called in to teach a course in RHEl admin, and that was the courseware that was chosen. i have a copy of the manual and it's actually not bad. and i'm not one to gratuitously compliment other peoples' courseware. :-)
rday
On Monday, August 09, 2010 02:06:51 pm Robert P. J. Day wrote:
as i'm reviewing the courseware for the rhel (centos) course i'm teaching next week, i'm going to ask the occasional question, possibly technical, possibly more policy.
first one involves the choice for virtualization. the course has a short section involving virt using xen but everything i've read suggests that red hat is concentrating on kvm for virt. thoughts on that? i have the freedom to replace the xen section with one covering kvm instead.
rday
I recommend using VirtualBOX from Sun. Close to wire speed, no need to alter the kernel. Simple and flexible to use.
I recommend using VirtualBOX from Sun. Close to wire speed, no need to alter the kernel. Simple and flexible to use.
I use VirtualBox on customer sites in order to virtualize a CentOS instance because it runs on Windows during the implementation phase, and then we can easily sneak it on their Solaris servers when it goes in production. I would never have been able to introduce a Linux over there without Virtual Box...
It works mostly fine and is the best FLOSS solution I have seen for desktop virtualization, but I don't find it rock-solid and they tend to release very often with significant changes. It feels like a Fedora rather than a CentOS, if you see what I mean. But updates have become much easier to follow since they set up a yum repository.
As per the OP question, I started preparing a virtualized infrastructure with CentOS 5 hosts (and guests) approximately one year ago and went the KVM way for the reason already described (mostly that it seems to be Red Hat long-term strategy). I never had any issue with KVM/QEMU/libvirt (so far...) and it is very easy to automate with virsh and the XML configurations (just as Xen I guess).
On Mon, Aug 09, 2010 at 03:17:10PM -0400, Bobby wrote:
I recommend using VirtualBOX from Sun. Close to wire speed, no need to alter the kernel. Simple and flexible to use.
No need to alter the kernel for KVM either. VirtualBox formerly from Sun has been gathering bugs since Oracle took over. Personally I wouldn't recommend it for serious use. It's a nice shiney toy though. But if you use, for instance, its snapshotting feature, and then something goes wrong, veteran users in the support forums will tell you you were a fool to ever trust the feature. Guess you're supposed to have an instinct about it. Simple is no good when major simple features aren't dependable.
Whit
On Monday, August 09, 2010 03:50:02 pm Whit Blauvelt wrote:
On Mon, Aug 09, 2010 at 03:17:10PM -0400, Bobby wrote:
I recommend using VirtualBOX from Sun. Close to wire speed, no need to alter the kernel. Simple and flexible to use.
No need to alter the kernel for KVM either. VirtualBox formerly from Sun has been gathering bugs since Oracle took over. Personally I wouldn't recommend it for serious use. It's a nice shiney toy though. But if you use, for instance, its snapshotting feature, and then something goes wrong, veteran users in the support forums will tell you you were a fool to ever trust the feature. Guess you're supposed to have an instinct about it. Simple is no good when major simple features aren't dependable.
Whit
Interesting, I've been using it to test install s/w and found it completely stable. Not once have I seen it crash using snapshot.
Indeed I've built on Linux and moved the client O/S's to both Windows and MAC and vice versa. The volume is not all that high, maybe 20 restores of a single snapshot, over and over.
I wonder what the conditions were that it failed under?
On Mon, Aug 09, 2010 at 11:11:59PM +0100, Karanbir Singh wrote:
Do you have some data to back this up ?
Yes. Search for my contributions to the VirtualBox forums and the VirtualBox bug reporting system. Also check for what experiences others are reporting there. I'm sure you'll agree it would be off topic for me to start getting into that degree of detail on the CentOS list.
Whit
On Mon, Aug 9, 2010 at 2:06 PM, Robert P. J. Day rpjday@crashcourse.ca wrote:
as i'm reviewing the courseware for the rhel (centos) course i'm teaching next week, i'm going to ask the occasional question, possibly technical, possibly more policy.
first one involves the choice for virtualization. the course has a short section involving virt using xen but everything i've read suggests that red hat is concentrating on kvm for virt. thoughts on that? i have the freedom to replace the xen section with one covering kvm instead.
I'm running both Xen and KVM.
If you're using the virt-* tools then RedHat does a pretty decent job of hiding the underlying virtualization engine. My virt-install script ran pretty much unchanged from Xen to KVM. If you're teaching a troubleshooting course, I think you need to cover both technologies as I do see a lot of Xen machines out there. Otherwise I'd concentrate on KVM and maybe give a few minutes on the differences (how disks are referenced, setting up bridging adapter, etc..).
as i'm reviewing the courseware for the rhel (centos) course i'm teaching next week, i'm going to ask the occasional question, possibly technical, possibly more policy.
first one involves the choice for virtualization. the course has a short section involving virt using xen but everything i've read suggests that red hat is concentrating on kvm for virt. thoughts on that? i have the freedom to replace the xen section with one covering kvm instead.
the one thing that hasn't been addressed yet by kvm scripts is that a shutdown/reboot of the host won't do a save/restore of the guests like xen can do. for that reason i still use xen for production systems and only use kvm for testing random distros.
On 08/12/2010 05:37 PM, Joe Pruett wrote: [snip]
the one thing that hasn't been addressed yet by kvm scripts is that a shutdown/reboot of the host won't do a save/restore of the guests like xen can do. for that reason i still use xen for production systems and only use kvm for testing random distros.
Fedora 13 does save the guest on shutdown so I would expect this will be supported in RHEL6/CentOS 6 too. But when do you actually power down a RHEL/CentOS server? And if you did, wouldn't you have migrated the guests to another box already?
Regards, Patrick
Fedora 13 does save the guest on shutdown so I would expect this will be supported in RHEL6/CentOS 6 too. But when do you actually power down a RHEL/CentOS server? And if you did, wouldn't you have migrated the guests to another box already?
mainly it is an issue for a quick reboot of the host for a kernel update. i guess migration is an option for that as well, but not everyone has that much hardware.
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Bobby -
James Hogarth -
Joe Pruett -
Karanbir Singh -
Kwan Lowe -
Mathieu Baudier -
Patrick Lists -
Paul Heinlein -
Robert P. J. Day -
Whit Blauvelt