Re: [Hampshire] Base OS for Xen
On Wed Jul 15, 2009 at 12:58:34 +0100, Dr A. J. Trickett wrote: > The userland part of KVM is mostly Qemu which is pretty mature already > so I'd say that while KVM is very new, it has grown up quickly and it's > still moving forward. I get the feeling that Xen is losing ground and > going out of fashion. It does seem to suffer from being so new though. I've certainly seen problems where heavy network IO will take down a guest unless you're running a very very recent kernel. > I think ByteMark went from User Mode Linux to KVM for their virtual > systems and now deploy KVM rather than Xen as their default way of > chopping a new system up. I gather that KVM is easier to work with - but > that's just a feeling I have no objective data to back it up. [I work for Bytemark but I'm not saying anything that isn't already public!] Bytemark hosted for many years based upon UML, and you're correct that these days if you rent a virtual machine it will be KVM-based. We had a brief trial of Xen but didn't find it ready for the prime time at the point the trial occurred. Later it did seem reliable, robust, and so on but we never switched to it for customer machines just for some of our internal systems. I'm with the later poster who suggested virtualisation is essentially a commodity at this point. KVM looks good at the moment, and the other in-kernel option is Rusty's lguest - I've only toyed with that but again its a nice simple system with a lot of flexibility. Xen? I think is destined for the sideline until it makes it fully into the kernel, and by then? I think it'll be overtaken. Steve -- http://www.steve.org.uk/ -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Base OS for Xen
On Wed, Jul 15, 2009 at 01:40:07PM +0100, Adam Trickett wrote: > On Wednesday 15 Jul 2009, Hugo Mills wrote: > > On Wed, Jul 15, 2009 at 12:58:34PM +0100, Adam Trickett wrote: > > > KVM is interesting, it's in the mainline kernel and Xen is > > > not. The firm behind KVM is now part of Red Hat and the firm > > > behind Xen is Citrix (a big Microsoft partner). > > > >There's quite a lot of Xen support in the kernel. It's not all in, > > and there has recently been a big argument on the linux-kernel list > > about the proposed changes for dom0 support. > > I thought as much, I knew Xen as big and there were a lot of arguments > last year. I know that KVM went in quite quickly, I believe it's very > simple. There's also quite a lot of chatter about KVM on linux-kernel: rather more than about Xen (although I may have missed Xen-related things because I don't know the people's names as well). This would indicate that the KVM developers are much more actively engaged with the kernel community, which is usually a good sign. > > > The userland part of KVM is mostly Qemu which is pretty mature > > > already > > > >Xen also uses qemu for its device emulation. > > Is there any VM solution that doesn't use Qemu? I gather VirtualBox uses > bits too. I don't think VMWare uses it. All the others that I'm aware of do, because it's a good, reliable and tested codebase for emulating PC platform hardware (and, indeed, a range of non-PC hardware). [snip] > >I've used Xen, VMWare, KVM and (k)qemu on various systems in the > > past. Of those, Xen was by far the hardest to get going sensibly. > > I've had some issues with VMWare not keeping their kernel module > > sources up to date with the latest kernel, requiring patches. kqemu > > didn't like running 64-bit guests on 64-bit hosts last time I tried > > (and when I reported the problem, got told to get out my debugger and > > get to work). > > My only gripe with Qemu is that at every significant upgrade, Windows NT > class clients refuse to boot because of subtle emulation changes. Linux > systems seem happy to keep running though. > > As far as I can tell a single Qemu disk-image can run under Qemu/kqemu > or KVM without modification which seems like a good idea to me. It's a > pity that VirtualBox can't use Qemu "Qcow" disk-image files directly. There's been some issues I've heard of with data corruption on qcow images recently. I don't recall the details, as I always use raw block devices instead, so I've not encountered it. Hugo. -- === Hugo Mills: h...@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- Hey, Virtual Memory! Now I can have a *really big* ramdisk! --- signature.asc Description: Digital signature -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Base OS for Xen
On Wednesday 15 Jul 2009, Hugo Mills wrote: > On Wed, Jul 15, 2009 at 12:58:34PM +0100, Adam Trickett wrote: > > On Wednesday 15 Jul 2009, Andy Smith wrote: > > > In my experience KVM has the most chance of not > > > encountering bizarre problems that no upstream > > > can/will take on. I believe Bytemark are using it > > > for their VM offering now, which was a big milestone. > > > > KVM is interesting, it's in the mainline kernel and Xen is > > not. The firm behind KVM is now part of Red Hat and the firm > > behind Xen is Citrix (a big Microsoft partner). > >There's quite a lot of Xen support in the kernel. It's not all in, > and there has recently been a big argument on the linux-kernel list > about the proposed changes for dom0 support. I thought as much, I knew Xen as big and there were a lot of arguments last year. I know that KVM went in quite quickly, I believe it's very simple. > > The userland part of KVM is mostly Qemu which is pretty mature > > already > >Xen also uses qemu for its device emulation. Is there any VM solution that doesn't use Qemu? I gather VirtualBox uses bits too. > > so I'd say that while KVM is very new, it has grown up quickly > > and it's still moving forward. I get the feeling that Xen is > > losing ground and going out of fashion. > >It's got significant problems, I think: architecturally, in terms > of usability, and apparently also in the development process. I think it's fair to say that Xen isn't the golden child any more! At the UKUUG meeting last year the Transitive people said that as far as they were concerned virtualisation is a commodity now and the money is doing smart stuff round the edges... > > I think ByteMark went from User Mode Linux to KVM for their virtual > > systems and now deploy KVM rather than Xen as their default way of > > chopping a new system up. I gather that KVM is easier to work with > > - but that's just a feeling I have no objective data to back it up. > >I've used Xen, VMWare, KVM and (k)qemu on various systems in the > past. Of those, Xen was by far the hardest to get going sensibly. > I've had some issues with VMWare not keeping their kernel module > sources up to date with the latest kernel, requiring patches. kqemu > didn't like running 64-bit guests on 64-bit hosts last time I tried > (and when I reported the problem, got told to get out my debugger and > get to work). My only gripe with Qemu is that at every significant upgrade, Windows NT class clients refuse to boot because of subtle emulation changes. Linux systems seem happy to keep running though. As far as I can tell a single Qemu disk-image can run under Qemu/kqemu or KVM without modification which seems like a good idea to me. It's a pity that VirtualBox can't use Qemu "Qcow" disk-image files directly. >These experiences are all somewhat out of date, so the situation > may have changed with some/all of them, but for a personal preference, > I'd opt for using kvm (if hardware permits) or qemu+kqemu. I thought that's what you said last time this came up on the list. I've not decided for certain but I fancy doing a virtualisation talk at one of the next meetings. I think desktop virtualisation is now easy enough for anyone and on the server it's become routine. -- Adam Trickett Overton, HANTS, UK With ... the fact that Linux has become so easy to install that certain species of bacteria are now being hired by MIS departments, what was once the domain of rigorously trained, highly specialised professionals has devolved into the Dark Land of the Monkeys. -- Greg Knauss -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Base OS for Xen
On Wed, Jul 15, 2009 at 12:58:34PM +0100, Adam Trickett wrote: > On Wednesday 15 Jul 2009, Andy Smith wrote: > > In my experience KVM has the most chance of not encountering bizarre > > problems that no upstream can/will take on. I believe Bytemark are > > using it for their VM offering now, which was a big milestone. > > KVM is interesting, it's in the mainline kernel and Xen is not. The firm > behind KVM is now part of Red Hat and the firm behind Xen is Citrix (a > big Microsoft partner). There's quite a lot of Xen support in the kernel. It's not all in, and there has recently been a big argument on the linux-kernel list about the proposed changes for dom0 support. > The userland part of KVM is mostly Qemu which is pretty mature already Xen also uses qemu for its device emulation. > so I'd say that while KVM is very new, it has grown up quickly and it's > still moving forward. I get the feeling that Xen is losing ground and > going out of fashion. It's got significant problems, I think: architecturally, in terms of usability, and apparently also in the development process. > I think ByteMark went from User Mode Linux to KVM for their virtual > systems and now deploy KVM rather than Xen as their default way of > chopping a new system up. I gather that KVM is easier to work with - but > that's just a feeling I have no objective data to back it up. I've used Xen, VMWare, KVM and (k)qemu on various systems in the past. Of those, Xen was by far the hardest to get going sensibly. I've had some issues with VMWare not keeping their kernel module sources up to date with the latest kernel, requiring patches. kqemu didn't like running 64-bit guests on 64-bit hosts last time I tried (and when I reported the problem, got told to get out my debugger and get to work). These experiences are all somewhat out of date, so the situation may have changed with some/all of them, but for a personal preference, I'd opt for using kvm (if hardware permits) or qemu+kqemu. Hugo. -- === Hugo Mills: h...@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 515C238D from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- Hey, Virtual Memory! Now I can have a *really big* ramdisk! --- signature.asc Description: Digital signature -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Base OS for Xen
On Wednesday 15 Jul 2009, Andy Smith wrote: > Hi Peter, > > On Tue, Jul 14, 2009 at 09:38:01PM +0100, Peter Brooks wrote: > > KVM I will look into too, some reports say it's not too mature > > yet but it's worth checking out (I'd actually forgotten about > > it until you mentioned it again). > > In my experience KVM has the most chance of not encountering bizarre > problems that no upstream can/will take on. I believe Bytemark are > using it for their VM offering now, which was a big milestone. KVM is interesting, it's in the mainline kernel and Xen is not. The firm behind KVM is now part of Red Hat and the firm behind Xen is Citrix (a big Microsoft partner). The userland part of KVM is mostly Qemu which is pretty mature already so I'd say that while KVM is very new, it has grown up quickly and it's still moving forward. I get the feeling that Xen is losing ground and going out of fashion. I think ByteMark went from User Mode Linux to KVM for their virtual systems and now deploy KVM rather than Xen as their default way of chopping a new system up. I gather that KVM is easier to work with - but that's just a feeling I have no objective data to back it up. > > The VM host will need to host windows and linux systems. > > I'd not discount VMWare then. If you pay your money then VMWare does have a good reputation, but it's not perfect. I currently use: VirtualBox on the desktop because it's dead easy and supports GUIs on the client system very well. KQemu/Qemu on my server because it's stable and fast. I tried VirtualBox on the server but it kept crashing in Debian Lenny, where Qemu was rock solid. My desktop systems run Squeeze okay though. Recently I tried KVM on my server, which was awkward to get going (permissions problems), but once I had it running it seems very similar to KQemu in stability and performance. -- Adam Trickett Overton, HANTS, UK I never really understood how there could be things that would drive you insane just because you knew them until I ran into Windows. -- anon -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Base OS for Xen
Hi Peter, On Tue, Jul 14, 2009 at 09:38:01PM +0100, Peter Brooks wrote: > KVM I will look into too, some reports say it's not too mature yet but > it's worth checking out (I'd actually forgotten about it until you > mentioned it again). In my experience KVM has the most chance of not encountering bizarre problems that no upstream can/will take on. I believe Bytemark are using it for their VM offering now, which was a big milestone. > The VM host will need to host windows and linux systems. I'd not discount VMWare then. Cheers, Andy -- http://bitfolk.com/ -- No-nonsense VPS hosting "What should one say after making love? ``Thank you'' seems too much. ``I'm sorry'' - somehow not enough." -- The League Against Tedium signature.asc Description: Digital signature -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Base OS for Xen
I've heard reports of the citrix distribution being "Handicapped", so I'll probably use Debian. Just really surveying VM options at the moment, we're updating the PE1950 to 8GB ECC with some additional storage too (currently on 1GB Ram, 80GB). KVM I will look into too, some reports say it's not too mature yet but it's worth checking out (I'd actually forgotten about it until you mentioned it again). The VM host will need to host windows and linux systems. Cheers On Tue, Jul 14, 2009 at 9:29 PM, Andy Smith wrote: > Hi Peter, > > On Tue, Jul 14, 2009 at 02:20:10PM +0100, Peter Brooks wrote: >> Just wondering what people have experimented about with for Xen base >> OS, I have a dell Poweredge 1950 that I'm experimenting with. I see >> two obvious choices as Debian or Xenserver but the citrix website for >> XenServer doesn't give too much away. > > Well Citrix Xenserver is its own distribution, so you won't get very > far looking for details of running it on other distributions and > avoiding giving them money. > > So when using the open source Xen stuff personally I would just use > whatever distribution I was most familiar with, as Xen works pretty > much the same on all of them. > > But I probably wouldn't use Xen in any new install today. I'd be > more likely to use KVM if the hardware supported it. I don't know > if your PE1950 does, or if you have other reasons for settling on > Xen. > > Cheers, > Andy > > -- > http://bitfolk.com/ -- No-nonsense VPS hosting > > "Xandros's low-level support for the Eee mostly seemed to consist of a pile > of shell scripts made of cheese and failure." -- Matthew Garrett > > -BEGIN PGP SIGNATURE- > Version: GnuPG v1.4.6 (GNU/Linux) > > iD8DBQFKXOqTIJm2TL8VSQsRA2RqAKDTVlEh0ptCB2PAyr4DruLynz/JbACbBhRr > hyNS/rwUaTtv06O3x6PjdeM= > =wXny > -END PGP SIGNATURE- > > -- > Please post to: Hampshire@mailman.lug.org.uk > Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire > LUG URL: http://www.hantslug.org.uk > -- > -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Base OS for Xen
Hi Peter, On Tue, Jul 14, 2009 at 02:20:10PM +0100, Peter Brooks wrote: > Just wondering what people have experimented about with for Xen base > OS, I have a dell Poweredge 1950 that I'm experimenting with. I see > two obvious choices as Debian or Xenserver but the citrix website for > XenServer doesn't give too much away. Well Citrix Xenserver is its own distribution, so you won't get very far looking for details of running it on other distributions and avoiding giving them money. So when using the open source Xen stuff personally I would just use whatever distribution I was most familiar with, as Xen works pretty much the same on all of them. But I probably wouldn't use Xen in any new install today. I'd be more likely to use KVM if the hardware supported it. I don't know if your PE1950 does, or if you have other reasons for settling on Xen. Cheers, Andy -- http://bitfolk.com/ -- No-nonsense VPS hosting "Xandros's low-level support for the Eee mostly seemed to consist of a pile of shell scripts made of cheese and failure." -- Matthew Garrett signature.asc Description: Digital signature -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Base OS for Xen
On Tue, 14 Jul 2009 16:44:35 +0100, m...@mjturner.net said: > I can definitely recommend Debian 5.0 (lenny) Interesting. I've just built a server running Lenny + Xen with six Lenny guests. The 'xm' command hangs from time to time, as do some of the guests. Nothing significant in the logs, but a number of bugs logged with Debian, significantly http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=517449 (the bug I'm seeing doesn't quite match that one, so it may be a different problem altogether). I've happily run Xen under Etch with no problems, but with Lenny is has been anything but plain sailing so far. -- Keith Edmunds +-+ |Tiger Computing Ltd| Helping businesses make the most of Linux | | "The Linux Specialists" | http://www.tiger-computing.co.uk | +-+ -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
Re: [Hampshire] Base OS for Xen
On Tue, Jul 14, 2009 at 02:20:10PM +0100, Peter Brooks wrote: > Just wondering what people have experimented about with for Xen base > OS, I have a dell Poweredge 1950 that I'm experimenting with. I see > two obvious choices as Debian or Xenserver but the citrix website for > XenServer doesn't give too much away. I can definitely recommend Debian 5.0 (lenny) - I've been using it as a Dom0 for over 6 months (since before it became stable) and am very happy with it. I've not used XenServer so can't comment on what it offers above and beyond the open source tools Debian provides though. -mj -- Michael-John Turner m...@mjturner.net <> http://mjturner.net/ -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
[Hampshire] Base OS for Xen
Hi all, Just wondering what people have experimented about with for Xen base OS, I have a dell Poweredge 1950 that I'm experimenting with. I see two obvious choices as Debian or Xenserver but the citrix website for XenServer doesn't give too much away. Any opinions or thoughts? -- Please post to: Hampshire@mailman.lug.org.uk Web Interface: https://mailman.lug.org.uk/mailman/listinfo/hampshire LUG URL: http://www.hantslug.org.uk --
