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1608 discussions

Xen dom0 support for CentOS-6
by Karanbir Singh 28 Jul '11

28 Jul '11

hi guys, This conversation seems to come up often; people are still quite keen on having dom0 support for CentOS-6; If we can answer a few questions, we can move that issue forward a bit : - What do we need to do in order to make that happen ? - What code needs to show up in CentOS/Extras or Plus ? - and is anyone willing to take ownership of handing this ? Regards, - KB

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(no subject)
by Grant McWilliams 28 Jul '11

28 Jul '11

http://nichejunky.com/google.php

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Re: [CentOS-virt] [Rocks-Discuss] Virtualizing RockCluster 5.3
by Nehemiah Dacres 27 Jul '11

27 Jul '11

is there a way to virtualize rocks5.2 on rocks5.4? I have been trying to and the gecko based install menu keeps failing. The error is a http 404 when looking for the release notes to display. any Idea of what causes that? I had that happen last time I tried to install rocks 5.2 on bare metal. The only notable thing about my network is that its on a 255.255.254.0 subnet mask. I can reserve its ip and everything. On Tue, Jul 13, 2010 at 12:58 AM, Jon Forrest <jlforrest(a)berkeley.edu>wrote: > On 7/12/2010 9:02 PM, Poh Yang Ming wrote: > >> Hi! >> >> I am trying to virtualize Rockcluster 5.3 for various testing with >> limited hardware. I have manage to get the headnode up in qemu >> (fedora13, x86_64). However, I am experiencing some issue to connect >> the headnode to the compute node. >> >> Has anyone done virtualization of rockcluster with qemu or has a >> better virtualization tools that is known to work? >> > > One possibility is to use VirtualBox. Take a look > at the method I posted about a couple of days ago > to see how I did it. > > Cordially, > -- > Jon Forrest > Research Computing Support > College of Chemistry > 173 Tan Hall > University of California Berkeley > Berkeley, CA > 94720-1460 > 510-643-1032 > jlforrest(a)berkeley.edu > > -- Nehemiah I. Dacres System Administrator Advanced Technology Group Saint Louis University

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Re: [CentOS-virt] Suggestions to improve this minimal kickstart config for CentOS 6?
by Manuel Wolfshant 22 Jul '11

22 Jul '11

On 07/20/2011 04:48 PM, Kartik Subbarao wrote: > On 07/19/2011 05:36 PM, Manuel Wolfshant wrote: >> Try the attached ks. It installs around 180 packages. libselinux-utils >> is in because I find it mandatory to be able to modify the selinux >> configuration of an existing system. > > Thanks for the info. I created a VM with this config and it took up > about 512MB of disk space, which is higher than the kickstart file > that I posted (about 460MB). you removed selinux and also used rpm -e --nodeps which I would never promote (even if I also use on occasions). ditch from my list the packages which install firmware and you'll end up at roughly the same size as yours. anyway my target was never minimal space on disk (today even CFs and SSD are several times larger than what the ks installs ) but minimal number of packages while still maintaining out of the box all the proper functionality ( or at least my vision on it), including for servers with real storage behind them ( brocade, etc ). and I emphasize again: including selinux tools. > I'm running x86_64 so I'll probably see different sizes than your > system which appears to be i686. my ks works on both, just adjust the repository used for install > > In any event, thanks for taking the time to post your kickstart file. > It helps me validate that what I have is reasonably minimal, that I'm > probably not missing any major sources of size reductions. welcome

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Many Xen related bugfixes and enhancements in RHEL 5.7 / CentOS 5.7
by Pasi Kärkkäinen 21 Jul '11

21 Jul '11

Hello, RHEL 5.7 has just been released, so here are some interesting Xen related bugfixes and enhancements in el5.7: Overview of Xen update in 5.7: http://rhn.redhat.com/errata/RHBA-2011-1070.html Technical notes about Xen changes in 5.7: https://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/5.7_Tech… Also kernel has a lot of fixes and updates: http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/5.7_Techn… Cheers, -- Pasi

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qemu-kvm -snapshot
by Andrea Chierici 19 Jul '11

19 Jul '11

Hi, I am trying to benchmark disk I/O performance on VM running with "-snapshot" option enabled. In order to do that I specify cache=none in the -drive parameter (yes I am running qemu-kvm at command line0. The problem is that if I use this option kvm seems to ignore the cache=none directive and I get weird output from iozone (I/O values are better than on the real machine, indicating that caching is enabled). The same command line, without "-snapshot" gives a correct output. Has anyone a clue about that? I succeeded in disabling cache in the past (with -snapshot enabled), but apparently this is not working anymore and I can't explain why. If this can help, here is the command line I am using: /usr/libexec/qemu-kvm -m 2048 -smp 1 -name test-1 \ -boot c -drive file=/var/lib/libvirt/images/test-1.img,if=virtio,index=0,boot=on,cache=none \ -net nic,macaddr=54:52:00:37:a9:eb,model=virtio -net tap \ -vnc 127.0.0.1:10 -k en-us -snapshot & the host is running centos5 and all latest updates are applied. Cheers, Andrea -- Andrea Chierici - INFN-CNAF Viale Berti Pichat 6/2, 40127 BOLOGNA Office Tel: +39 051 6092809 ICQ#2328798, MSN#ataruz<at>gmail.com, Skype#ataruz --

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CentOS-6.0 and LXC
by Matt Paine 19 Jul '11

19 Jul '11

Hi Guys. Hope someone can point me in the right direction. I would like to get into LXC and evaluate its usefulness compared with Linux-VServer. I notice that LXC is in tech preview upstream, however I am at a dead end trying to figure out how to get started. I cannot find any usertools in the rpm's that ship with CentOS 6. Is this because the tech preview requires me to get the tools outside the standard repo's? Of course I am happy to do that, but at the same time I prefer to use tools that are within the CentOS eco-system where possible. Any help pointing me to documentation specifically with CentOS/RHEL/otherEL (6) will be greatly appreciated. I have not been able to find anything useful in my efforts so far. Thank you. Matt.

5 7

Now on to creation of disk images
by Steve Campbell 18 Jul '11

18 Jul '11

Mr. Heron was so kind to make a suggestion that I should use disk images to install VMs. Upon further thought, I kinda like the idea. So I re-read the manual and google a little, and discover I still don't know what should be in these disk images. Should I copy the contents of the CDs to a file or what? I've got a test server at the moment with Centos 5.5 and xen installed as the host OS, but have just downloaded the 5.6 CD ISOs along with the DVD ISO, so I'll use 5.6 for my VMs. I've read about how I can create an image from something that already exists. Again, any clarity would be appreciated. steve campbell

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CentOS 6 and KVM woes
by Trey Dockendorf 17 Jul '11

17 Jul '11

I have decided to migrate my latest KVM server to CentOS 6.0 and am beginning to get a little frustrated with some issues that worked perfectly in 5.6. Right now I've given up on getting virbr0 and NAT to work, but now I need networking bridging to work, but nothing seems to fix the issue. I have not had much experience with troubleshooting KVM so could really use some pointers on resolving this issue. I have successfully bridged one of the server's NICs to br0, and I can ping the IP remotely that is assigned to br0, but none of the VMs that worked in 5.6's KVM are able to access the network. Please let me know what information would be useful to troubleshoot this. Here's what I have so far... ifcfg-eth3... --------------------------------- DEVICE="eth3" HWADDR="00:1B:21:A1:CF:76" ONBOOT="yes" BRIDGE=br0 ifcfg-br0 -------------------------------- DEVICE=br0 TYPE=Bridge BOOTPROTO=static ONBOOT=yes IPADDR=.... BROADCAST=.... NETMASK=.... NETWORK=.... # brctl show bridge name bridge id STP enabled interfaces br0 8000.001b21a1cf76 no eth3 sysctl.conf has these 3 additional lines... net.bridge.bridge-nf-call-ip6tables = 0 net.bridge.bridge-nf-call-iptables = 0 net.bridge.bridge-nf-call-arptables = 0 Again I can ping br0's IP remotely , but no VMs assigned to it can access even that network's gateway. I have disabled iptables and ip6tables for now while trying to get this to work. The VMs , worked just fine in 5.6 and I have done nothing different but import them with virsh. Thanks - Trey

6 11

IPtables and Libvirt
by Trey Dockendorf 17 Jul '11

17 Jul '11

Running CentOS 6 I have noticed that Libvirt will automatically configure IPtables once a VM is using the built in NAT , or "default" network. How do I modify the IPtable rules without breaking libvirt's ability to configure these rules? This is the firewall settings on a fresh install with no VMs using virbr0... -------------------------- Table: filter Chain INPUT (policy ACCEPT) num target prot opt source destination 1 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 2 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 3 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 4 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22 5 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited Chain FORWARD (policy ACCEPT) num target prot opt source destination 1 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 PHYSDEV match --physdev-is-bridged 2 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited Chain OUTPUT (policy ACCEPT) num target prot opt source destination And this is what I see after a reboot or once a VM uses the NAT ---------------------------- Table: mangle Chain PREROUTING (policy ACCEPT) num target prot opt source destination Chain INPUT (policy ACCEPT) num target prot opt source destination Chain FORWARD (policy ACCEPT) num target prot opt source destination Chain OUTPUT (policy ACCEPT) num target prot opt source destination Chain POSTROUTING (policy ACCEPT) num target prot opt source destination 1 CHECKSUM udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:68 CHECKSUM fill Table: nat Chain PREROUTING (policy ACCEPT) num target prot opt source destination Chain POSTROUTING (policy ACCEPT) num target prot opt source destination 1 MASQUERADE tcp -- 192.168.122.0/24 !192.168.122.0/24 masq ports: 1024-65535 2 MASQUERADE udp -- 192.168.122.0/24 !192.168.122.0/24 masq ports: 1024-65535 3 MASQUERADE all -- 192.168.122.0/24 !192.168.122.0/24 Chain OUTPUT (policy ACCEPT) num target prot opt source destination Table: filter Chain INPUT (policy ACCEPT) num target prot opt source destination 1 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:53 2 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:53 3 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:67 4 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:67 5 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED 6 ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 7 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 8 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22 9 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited Chain FORWARD (policy ACCEPT) num target prot opt source destination 1 ACCEPT all -- 0.0.0.0/0 192.168.122.0/24 state RELATED,ESTABLISHED 2 ACCEPT all -- 192.168.122.0/24 0.0.0.0/0 3 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 4 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable 5 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable 6 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 PHYSDEV match --physdev-is-bridged 7 REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited Chain OUTPUT (policy ACCEPT) num target prot opt source destination My concern is that if I begin to add custom rules that it will break this setup. If I run "service iptables save" after adding a rule, IPtables will then have saved this dynamic configuration. I assume it's dynamic because "/etc/sysconfig/iptables" does not reflect the second set of rules I pasted, but rather the first even when the second set is showing as active. Thanks - Trey

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