jd:/dev/blog - Xen

Novell and RedHat fighting about Xen

jd — Fri, 11 Aug 2006 15:37:55 +0000

Some days ago, RedHat claims that Xen is not ready yet for production environment. Now, Novell strikes back and defend their inclusion of Xen in their latest SUSE release.

That's so funny, because in fact they don't give any concret argument. RedHat says that it's not mature, and Novell just answers that they've contributed to the code.

As a member of the Debian Xen team, I'll arbitrate between us.

Xen is nowadays deployed in a lot of solution and in a lot of system architecture. I don't think this is because the Xen technology is mature, but only because it's the solution which fit the best the need of virtualization (and cost rationalisation) that organizations may have.

Xen can not pretend to be stable, mature, or whatever you want, because it is still not integrated into the Linux kernel tree, and thus far for a good reason: the API/ABI is not yet stable.
I know that in theory it is, but in fact it's quite wrong and you cannot rely on that specification. Xen works fine but from a developer point of view it is not in a stable and fixed shape.

It seems that Linus and others kernel people are not very happy to integrate directly Xen into the mainline kernel, and I can understand them, since this technology is rather new. I don't think Xen will be a suitable solution which can be deployed for years until Linus decide to integrate a virtualization system into the Linux kernel.

Furthermore, Xen is still a huge source tarball of mess with a big kernel patch.

And even if I really think that Xen will be the adopted solution for everyone, it won't be in its current state.

So, I think RedHat is pretty right. Just think about the Xgl/AIGLX stuff, that's quite again the same behavior between this two companies.

Xen backports

jd — Wed, 17 May 2006 08:10:24 +0000

Guido's backports of Xen 3 Debian packages just entered backports.org repository.

Debian Xen howto up to date

jd — Wed, 10 May 2006 17:54:49 +0000

I just upgraded my Xen installation at home this week-end, so I updated my Xen Debian howto. Now it is up to date, and it's here. It covers Xen installation for both Sarge and Etch.

NetBSD 3 in Xen

jd — Fri, 07 Apr 2006 22:33:15 +0000

It works. I just installed a NetBSD 3 as Xen 3 DomU using this kernels.

NetBSD thor.adm.naquadah.org 3.99.17 NetBSD 3.99.17 (XEN3_U) #5: Sat Mar 25 19:01:14 CET 2006 bouyer@blues.lip6.fr:/Volumes/data/bouyer/tmp/i386/obj/Volumes/data/bouyer/current/src/sys/arch/i386/compile/XEN3_U i386

Xen howto update

jd — Mon, 03 Apr 2006 16:06:30 +0000

I just updated my Xen 3 for Debian howto, because it was still talking about Xen 2.

Now it relies on official Debian packages.

NetBSD/Xen unstable :(

jd — Wed, 17 Aug 2005 16:31:00 +0000

While compiling lftp:

uvm_swapin: rewiring stack failed: 5                              
Stopped in pid 0.1 (swapper) at netbsd:cpu_Debugger+0x4:        leave           
cpu_Debugger(c389c6b4,0,c033af48,c389c6b4,c389c6b4) at netbsd:cpu_Debugger+0x4  
panic(c029d1e0,5,c033af68,c0234023,c389c6b4) at netbsd:panic+0x11d              
uvm_scheduler(c389c6b4,c02800cd,c033af68,c0233f56,0) at netbsd:uvm_scheduler    
uvm_scheduler(c02e73a0,0,c02eb73c,c027de96,1) at netbsd:uvm_scheduler+0xcf      
main(0,0,0,0,0) at netbsd:main+0x68f                                            
ds          0x11                                                                
es          0x11                                                                
fs          0x31                                                                
gs          0x11                                                                
edi         0x1                                                                 
esi         0x100                                                               
ebp         0xc033af08  xbd_allxr+0x4c268                                       
ebx         0xc033af34  xbd_allxr+0x4c294                                       
edx         0                                                                   
ecx         0                                                                   
eax         0x61e                                                               
eip         0xc0244d00  cpu_Debugger+0x4                                        
cs          0x9                                                                 
eflags      0x202                                                               
esp         0xc033af08  xbd_allxr+0x4c268                                
ss          0x11                                                                
netbsd:cpu_Debugger+0x4:        leave                                           
Stopped in pid 0.1 (swapper) at netbsd:cpu_Debugger+0x4:        leave

The same thing happened if I use my xennet devices heavily...

xen rocks

jd — Sun, 07 Aug 2005 16:46:00 +0000

I decided that I had enough of having plenty of computers running at home to run a gateway, a workstation, a server, a dev(a)station, etc...

I gave a try to some virtualizations things like vserver. This one does not do what I want, because it's only a kernel patched with a context support.
This is like a powerful chroot() system, but for examples, this is not very good for doing routing stuff, because you have only one kernel and all IP adresses are bound to your real interfaces.

So I tried Xen, and it is very very nice. I can run as many computers (and so, kernel) as I want and they act like real computers, not a computer with chrooted services (like vserver). You can also put your virtual node on the CPU you want, distribute your RAM as you want and emulate the number of NIC you want to. I like that.
Network access between kernel are made using Ethernet bridges, which is very nicer than the vserver method.

You can also run NetBSD hosts in your XenLinux host. I think I will give it a try too, probably to emulate my gateway.

This is more powerful than UML too.

In consequence, I plan to replace my current 3 machines with a big one (2.4 GHz/1 GB RAM), emulating 3 nodes: a gateway/firewall, a developpement station and a server for my local services.