Hello, I just setup a few virtual systems, and I came into some limitations using XEN. I''d like to share these, just to know if the limitations are in the system or in the user :) I am using a standard Debian 4.0 (etch) GNU/Linux distribiution. The system is an Intel Core 2 duo with virtualization inside. I use the amd64 flavour. Thus my kernel is ''2.6.18-4-xen-amd64''. Xen is version 3.0.3. Using paravirtualization, I can start only other 64 bits guests. Either the standard linux-image-2.6.18-4-xen-amd64, Or a specially compiled one, with IDE included not-as-module I cannot manage to start the ubuntu 7.04 kernels for amd64. Using full virtualization (hvm), I can start only 32 bits guests. Starting on an ISO of a Debian amd64 or Fedora x86_64 install fails. But starting on a i386 ISO of these allows the install to run OK. Using hvm, I have to use ioemu for the network card to be recognized. vif = [ "type=ioemu, ip=..." ] without it, the card is not detected. BTW, I am using NAT for networking. Then, starting to use all of these is a bit of a nightmare. Indeed hvm systems do start but does not show the SDL display. xm list reports the system as running, but I have no access to it (and network not yet configured) although it was present during install. Don''t know what happends here. I''d be glad for some hints? One more question, how to mount inside dom0 a logical volume that is given as a whole disk to a hvm (which had it partitionned). Thanks in advance Didier -- Didier Trosset-Moreau Agilent Technologies Geneva, Switzerland _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > Didier Trosset > Sent: 27 April 2007 14:56 > To: xen-users@lists.xensource.com > Subject: [Xen-users] Debian/Xen usage summary > > Hello, > > I just setup a few virtual systems, and I came into some > limitations using > XEN. I''d like to share these, just to know if the limitations > are in the > system or in the user :) > > I am using a standard Debian 4.0 (etch) GNU/Linux > distribiution. The system > is an Intel Core 2 duo with virtualization inside. I use the > amd64 flavour. > Thus my kernel is ''2.6.18-4-xen-amd64''. Xen is version 3.0.3. > > Using paravirtualization, I can start only other 64 bits guests. > Either the standard linux-image-2.6.18-4-xen-amd64, > Or a specially compiled one, with IDE included not-as-module > I cannot manage to start the ubuntu 7.04 kernels for amd64.This is normal and expected - the PV kernel and Dom0 + Hypervisor needs to be "same type" (64-bit, 32-bit PAE or 32-bit). Release of 3.0.5 (RC3 available now) will change this to allow 32-PAE on top of 64-bit (32-bit without PAE is much harder as 64-bit and 32PAE share a very similar page-table format, whilst the NOPAE uses a noticable differnet page-table format).> > Using full virtualization (hvm), I can start only 32 bits guests. > Starting on an ISO of a Debian amd64 or Fedora x86_64 > install fails. > But starting on a i386 ISO of these allows the install to run OK.64-bit guests of some sorts should work fine in 3.0.3 - but some may not. However, if you can''t get any guests to work in 64-bit, I guess that there''s some settings missing in the config file: apic=1, pae=1 should be the minimum. Changing the setting of acpi={1,0} may also contribute to success - try both options to see if one is better than the other. However, bear in mind that significant effort was put into 3.0.4''s 64-bit support, so some guests will work much better with a 3.0.4 or later version of Xen.> > Using hvm, I have to use ioemu for the network card to be recognized. > vif = [ "type=ioemu, ip=..." ] without it, the card is not > detected. > BTW, I am using NAT for networking.Yes, you probably need IOEMU here to tell the builder where the network device is (theoretically, it could be a para-virtual device, so if it''s not declared IOEMU, the builder may set it up as a PV device, which of course doesn''t work for full-virtualization unless the guest has special para-virtual drivers added to the guest).> > Then, starting to use all of these is a bit of a nightmare. > Indeed hvm > systems do start but does not show the SDL display. xm list > reports the > system as running, but I have no access to it (and network not yet > configured) although it was present during install. Don''t > know what happends > here. I''d be glad for some hints?Use VNC instead? I suspect that the SDL option wasn''t compiled into your (i.e. debian''s) QEMU model, but that''s just a guess. Try checking the /var/log/xen/qemu-dm.*.log files to see if it says anything about SDL/VNC/etc in there? [I generally use SDL, but I''ve used VNC lately too - both needs to compiled in when building the qemu-dm application] Of course, it could be any of a hundred other problems... :-( -- Mats> > One more question, how to mount inside dom0 a logical volume > that is given > as a whole disk to a hvm (which had it partitionned). > > Thanks in advance > Didier > > -- > Didier Trosset-Moreau > Agilent Technologies > Geneva, Switzerland > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
Didier: I am using Fedora Core 6 (2.6.18 kernl, 2.6.20 buggy) with Xen 3.0.3 and have a x86_64 Dom0. Currently we are only running fully virtualized guests so I cannot comment on the paravirtualization. We have run into both the same issues that you are experiencing. Only 32 bit guests (which in our case is fine) and only type=ioemu for the network card. We have found network performance to be on the low end as well in these guests and have yet to find a solution. One thing I noticed staying with the network issue is that while Dom0 is a Gigabit Ethernet device and recognized properly, the DomU machines are only being setup as 100 Mbit Ethernet devices. Is there a way to get a gigabit card in the DomU that anybody knows for an HVM guest? What about any tricks for optimizing performance? Finally, working with LVM images I can help as we have needed to do that as well. There is a good article at: http://www.campworld.net/thewiki/pmwiki.php/Linux/DiskImagesHOWTO Sorry, I could not help with the other items, hopefully somebody else on the list will have more information for us. -----Original Message----- From: xen-users-bounces@lists.xensource.com [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Didier Trosset Sent: Friday, April 27, 2007 8:56 AM To: xen-users@lists.xensource.com Subject: [Xen-users] Debian/Xen usage summary Hello, I just setup a few virtual systems, and I came into some limitations using XEN. I''d like to share these, just to know if the limitations are in the system or in the user :) I am using a standard Debian 4.0 (etch) GNU/Linux distribiution. The system is an Intel Core 2 duo with virtualization inside. I use the amd64 flavour. Thus my kernel is ''2.6.18-4-xen-amd64''. Xen is version 3.0.3. Using paravirtualization, I can start only other 64 bits guests. Either the standard linux-image-2.6.18-4-xen-amd64, Or a specially compiled one, with IDE included not-as-module I cannot manage to start the ubuntu 7.04 kernels for amd64. Using full virtualization (hvm), I can start only 32 bits guests. Starting on an ISO of a Debian amd64 or Fedora x86_64 install fails. But starting on a i386 ISO of these allows the install to run OK. Using hvm, I have to use ioemu for the network card to be recognized. vif = [ "type=ioemu, ip=..." ] without it, the card is not detected. BTW, I am using NAT for networking. Then, starting to use all of these is a bit of a nightmare. Indeed hvm systems do start but does not show the SDL display. xm list reports the system as running, but I have no access to it (and network not yet configured) although it was present during install. Don''t know what happends here. I''d be glad for some hints? One more question, how to mount inside dom0 a logical volume that is given as a whole disk to a hvm (which had it partitionned). Thanks in advance Didier -- Didier Trosset-Moreau Agilent Technologies Geneva, Switzerland _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of > Larry A Weidig > Sent: 27 April 2007 15:27 > To: xen-users@lists.xensource.com > Subject: RE: [Xen-users] Debian/Xen usage summary > > Didier: > I am using Fedora Core 6 (2.6.18 kernl, 2.6.20 buggy) with Xen > 3.0.3 and have a x86_64 Dom0. Currently we are only running fully > virtualized guests so I cannot comment on the paravirtualization. We > have run into both the same issues that you are experiencing. Only 32 > bit guests (which in our case is fine) and only type=ioemu for the > network card. We have found network performance to be on the > low end as > well in these guests and have yet to find a solution. > One thing I noticed staying with the network issue is that while > Dom0 is a Gigabit Ethernet device and recognized properly, the DomU > machines are only being setup as 100 Mbit Ethernet devices. > Is there a > way to get a gigabit card in the DomU that anybody knows for an HVM > guest? What about any tricks for optimizing performance?Since there is no "real wire" involved in the transfer across the network within the machine (that is, before the network hits Dom0), there''s no real meaning to the {10M, 100M, 1G}bps used for wired networks, because it''s using a virtual network device anyways, not a REAL network device. So, assuming your machine is capable, you could get 1000Gbps on the network between DomU and Dom0 even if you have a 10Mbps network device! [Although currently, I''d say you''ll probably struggle to get much more than 10Mbps out of the virtualized network adapter] The slowness involved in the network traffic is all to do with the fact that there is a SIGNIFICANT overhead in the way that the virtual device modeling is done. First of all, whenever a hardware access is done, the guest will "exit" back to the hypervisor, which will forward the access to Dom0''s "qemu-dm", where the hardware access is then interpreted and "performed". Network devices are actually much better here than for example IDE-disk accesses, as most network devices are fairly low number of accesses per packet. But there''s still some communication per packet needed. One of the majror causes of delay is Dom0 being busy. If you can make sure that Dom0 isn''t doing anything else (and runs on it''s own core(s) that aren''t being used by any other domain). But the biggest gain would be to completely skip the virtualized network adapter and use a para-virtual driver. This is a driver that is aware that the network device isn''t a "real" device, but rather just packets up the network packet and forwards it directly to Dom0. It''s still a little bit of overhead (particularly if Dom0 is busy doing "other things") compared to a real machine with it''s direct access to a network card, but the overhead is significantly lower as there''s only ONE interaction with Dom0 per packet. PV drivers are available for Network and Disk. Linux PV drivers are included in the Xen source code (at least in the CURRENT code - not sure when they got included, 3.0.3 or 3.0.4), and Windows ones are available in some distributions that contain Xen, for example XenExpress (although using those drivers for a different version of Xen than the one used in XenExpress may cause problems - I haven''t tried myself, but my collegues reported problems doing that). -- Mats> Finally, working with LVM images I can help as we have needed to > do that as well. There is a good article at: > > http://www.campworld.net/thewiki/pmwiki.php/Linux/DiskImagesHOWTO > Sorry, I could not help with the other items, hopefully > somebody else on the list will have more information for us. > > -----Original Message----- > From: xen-users-bounces@lists.xensource.com > [mailto:xen-users-bounces@lists.xensource.com] On Behalf Of Didier > Trosset > Sent: Friday, April 27, 2007 8:56 AM > To: xen-users@lists.xensource.com > Subject: [Xen-users] Debian/Xen usage summary > > Hello, > > I just setup a few virtual systems, and I came into some limitations > using > XEN. I''d like to share these, just to know if the limitations > are in the > > system or in the user :) > > I am using a standard Debian 4.0 (etch) GNU/Linux distribiution. The > system > is an Intel Core 2 duo with virtualization inside. I use the amd64 > flavour. > Thus my kernel is ''2.6.18-4-xen-amd64''. Xen is version 3.0.3. > > Using paravirtualization, I can start only other 64 bits guests. > Either the standard linux-image-2.6.18-4-xen-amd64, > Or a specially compiled one, with IDE included not-as-module > I cannot manage to start the ubuntu 7.04 kernels for amd64. > > Using full virtualization (hvm), I can start only 32 bits guests. > Starting on an ISO of a Debian amd64 or Fedora x86_64 > install fails. > But starting on a i386 ISO of these allows the install to run OK. > > Using hvm, I have to use ioemu for the network card to be recognized. > vif = [ "type=ioemu, ip=..." ] without it, the card is not > detected. > BTW, I am using NAT for networking. > > Then, starting to use all of these is a bit of a nightmare. > Indeed hvm > systems do start but does not show the SDL display. xm list > reports the > system as running, but I have no access to it (and network not yet > configured) although it was present during install. Don''t know what > happends > here. I''d be glad for some hints? > > One more question, how to mount inside dom0 a logical volume that is > given > as a whole disk to a hvm (which had it partitionned). > > Thanks in advance > Didier > > -- > Didier Trosset-Moreau > Agilent Technologies > Geneva, Switzerland > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users > > > _______________________________________________ > Xen-users mailing list > Xen-users@lists.xensource.com > http://lists.xensource.com/xen-users > > >_______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users
> ---- 8< ---->> Then, starting to use all of these is a bit of a nightmare. Indeed hvm >> systems do start but does not show the SDL display. xm list reports the >> system as running, but I have no access to it (and network not yet >> configured) although it was present during install. Don''t know what >> happends here. I''d be glad for some hints? > > Use VNC instead? I suspect that the SDL option wasn''t compiled into your > (i.e. debian''s) QEMU model, but that''s just a guess. Try checking the > /var/log/xen/qemu-dm.*.log files to see if it says anything about > SDL/VNC/etc in there? [I generally use SDL, but I''ve used VNC lately too > - both needs to compiled in when building the qemu-dm application]I''m pretty sure SDL is compiled within, as I ran the install correctly within the SDL window. The trouble is that when restarting after the install (with boot=''c'') there is no SDL display window that opens anymore! I''d like it just once to setup networking and ssh server. (Then I already plan to switch to vnc to have no window when hvm is running.) -- Didier Trosset-Moreau Agilent Technologies Geneva, Switzerland _______________________________________________ Xen-users mailing list Xen-users@lists.xensource.com http://lists.xensource.com/xen-users