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Re: [CentOS-virt] Centos 5.2, Xen and "/lib[64]/tls"
by Christopher G. Stach II 14 Feb '09

14 Feb '09

----- "Manuel Wolfshant" <wolfy(a)nobugconsulting.ro> wrote: > Dennis J. wrote: > > Hi, > > > > I'm setting up a few machines for virtualization using Xen on Centos > 5.2 > > x86_64. A lot of how-to's out there tell me to do something like "mv > > > /lib/tls /lib/tls.disabled" or similar actions or else Xen might not > work > > correctly. Is this something that is still relevant > No, it is not relevant since 2006 It may be relevant since it depends on the guest. It's not clear in the original post whether it's the host or the guest that's 5.2. In the worst case, the guests will just be a little slow. :) -- Christopher G. Stach II

2 2

Centos 5.2, Xen and "/lib[64]/tls"
by Dennis J. 13 Feb '09

13 Feb '09

Hi, I'm setting up a few machines for virtualization using Xen on Centos 5.2 x86_64. A lot of how-to's out there tell me to do something like "mv /lib/tls /lib/tls.disabled" or similar actions or else Xen might not work correctly. Is this something that is still relevant or does it only apply to older versions of Xen/Centos? If this is still necessary what is the best way to disable this permantently so that after an update the directory doesn't get created again? Regards, Dennis

2 1

Centos 5.2 Xen question?
by Leam Hall 11 Feb '09

11 Feb '09

Did this one ever get resolved? I'm having the same issue with a different card set. http://lists.centos.org/pipermail/centos-virt/2008-January/000192.html Leam

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Re: [CentOS-virt] Alternate console method for Windows 2003 server
by Christopher G. Stach II 09 Feb '09

09 Feb '09

----- "James Roman" <james_roman(a)ssaihq.com> wrote: > I have a DomU running Windows 2003 server that occasionally blue > screens > (or at least I assume it does). Obviously, when it does, I lose the > ability to open a VNC console. Is there some method for sending the > windows console to another location that can be viewed if the system > dies? Just read the Windows event log and/or crash dump. -- Christopher G. Stach II

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Alternate console method for Windows 2003 server
by James Roman 09 Feb '09

09 Feb '09

I have a DomU running Windows 2003 server that occasionally blue screens (or at least I assume it does). Obviously, when it does, I lose the ability to open a VNC console. Is there some method for sending the windows console to another location that can be viewed if the system dies? Centos 5.2 2.6.18-92.1.6.el5xen kernel -- James D. Roman Sr. Network Administrator Science Systems and Application, Inc. Phone: 301-867-2101

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patched kernel addressing timekeeping issues under vmware
by Akemi Yagi 06 Feb '09

06 Feb '09

People at vmware have provided patches for RHEL 5 that aim to fix timekeeping issues in vmware guests. https://bugzilla.redhat.com/show_bug.cgi?id=463573 Description of problem (excerpt) : "In a virtual environment, timekeeping for RHEL 64 bit kernels can be problematic, since time is kept by counting timer interrupts for this kernel. The problem arises when the VM is descheduled for some portion of time. When the VM is rescheduled, the hypervisor needs to "catch up" delivering timer interrupts so that the kernel can determine the correct time. Until the VM is caught up, the kernel's time will be behind, causing short term divergence of the kernel's time with wallclock time. Additionally, under certain overcommitment conditions, it may not be possible for the hypervisor to fully catch up. In this case, the kernel time can fall behind over the long term. The solution is to change the kernel's timekeeping algorithm to keep time based on how much time has elapsed according to a time counter rather than by counting interrupts. This is similar to the timeofday algorithm used by clocksource enabled mainline kernels or the RHEL5 32bit kernel." They were hoping to get them into the RHEL 5.3 kernel but unfortunately this is not going to happen. It looks like the patches will be in the RHEL 5.4 kernel. Using the patches provided in the bugzilla, I have rebuilt the latest test kernel (-125) that is available from http://people.redhat.com/dzickus. You can download the patched kernel from: http://centos.toracat.org/kernel/centos5/vmware463573/ I have test-installed it on a couple of CentOS-5 x86_64 guests. Still too early to say anything about the clock issue, but so far so good. If you get a chance to give it a try, please share what you find. Thanks, Akemi (nick: toracat)

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Re: [CentOS-virt] Mixed dom0/domU usage?
by Christopher G. Stach II 05 Feb '09

05 Feb '09

----- "Dennis J." <dennisml(a)conversis.de> wrote: > Hi, > I'm wondering about the impact of using both dom0 and domU's on a > server at > the same time. I'm worried about the performance impact of running a > Mysql > server in a domU and now I'm thinking about moving the Mysql part of a > LAMP > setup into dom0 and running a few Apache guests as domUs. Since the > Apaches > will serve mostly from an NFS share they won't have much impact on the > disk > i/o so the database should be able to utilize the local storage > without > much interference from the guests. The plan is to limit dom0 to let's > say > 4gb of ram and then use the rest of it for the VMs. > > Has anyone experinece with this kind of "mixed" setup > (physical/virtual). > Are there any known problems with this approach? Running processes in dom0 that aren't for running Xen is going to destroy your domU I/O performance. The backends are just processes. If you take time away from those processes for other things, performance will suffer. You should run some load tests and see if it suits your model, though. Running the MySQL process in dom0 isn't going to get you very much of a performance boost if your MySQL configuration is tuned properly, either. -- Christopher G. Stach II

4 7

Xen, Qemu and Intel VT
by Nunzio Losacco 05 Feb '09

05 Feb '09

Hi everyone, I need to use full virtualization on my laptop, running CentOS 5.2 as host. I installed all I think is needed to run Xen. I am using kernel 2.6.18-128el5.xen as it is needed to recognize my wifi card. I was not sure my cpu supported Intel VT. A cat /proc/cpuinfo | grep flags yields this: flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx lm constant_tsc pni monitor ds_cpl vmx smx est tm2 cx16 xtpr lahf_lm I guess vmx means VT is supported even if, for my T9600 cpu, it is not officially stated on Intel website (it is up to T9400). VT is enabled in the BIos. When I try to add a virtual machine with virt-manager choosing Xen as hypervisor, the "enable kernel/hardware acceleration" checkbox is grayed out. How can I solve this? Moreover, if I run CentOS on a non-Xen kernel (i.e.: 2.6.18-128el5) I cannot use xen of course, but if I choose Qemu as hypervisor in virt-manager, the checkbox is available. How can it be? Thank you very much for your help, N.

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Re: [CentOS-virt] Mixed dom0/domU usage?
by Christopher G. Stach II 04 Feb '09

04 Feb '09

----- "Kai Schaetzl" <maillists(a)conactive.com> wrote: > Ben Montanelli wrote on Wed, 04 Feb 2009 11:50:04 -0500: > > > I guess many of us want the optimized "grail" dom0. > > There is none. It depends on your needs. This is pretty close to one. :) I also attached a trimmed down version of the kickstart config I use for dom0s. Some of it is irrelevant to many people, but I figured someone would find something useful in it, like fixing some of the brokenness. Some of the packages (like the ones for NTP, MD RAID, IPMI, LUKS, and iSCSI) can be removed if you don't need them. ntpd and snmpd can be disabled if you don't need/use them, or for security policy reasons, as well. dom0 services: srv1:[1:13pm]:120:~# chkconfig --list | grep :on acpid 0:off 1:off 2:off 3:on 4:on 5:on 6:off auditd 0:off 1:off 2:on 3:on 4:on 5:on 6:off cpuspeed 0:off 1:on 2:on 3:on 4:on 5:on 6:off crond 0:off 1:off 2:on 3:on 4:on 5:on 6:off edac 0:off 1:off 2:on 3:on 4:on 5:on 6:off ip6tables 0:off 1:off 2:on 3:on 4:on 5:on 6:off iptables 0:off 1:off 2:on 3:on 4:on 5:on 6:off libvirtd 0:off 1:off 2:off 3:on 4:on 5:on 6:off lm_sensors 0:off 1:off 2:on 3:on 4:on 5:on 6:off lvm2-monitor 0:off 1:on 2:on 3:on 4:on 5:on 6:off mcstrans 0:off 1:off 2:on 3:on 4:on 5:on 6:off mdmonitor 0:off 1:off 2:on 3:on 4:on 5:on 6:off network 0:off 1:off 2:on 3:on 4:on 5:on 6:off ntpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off postfix 0:off 1:off 2:on 3:on 4:on 5:on 6:off restorecond 0:off 1:off 2:on 3:on 4:on 5:on 6:off smartd 0:off 1:off 2:on 3:on 4:on 5:on 6:off snmpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off sshd 0:off 1:off 2:on 3:on 4:on 5:on 6:off syslog 0:off 1:off 2:on 3:on 4:on 5:on 6:off sysstat 0:off 1:off 2:on 3:on 4:off 5:on 6:off xend 0:off 1:off 2:on 3:on 4:on 5:on 6:off xendomains 0:off 1:off 2:off 3:on 4:on 5:on 6:off dom0 kickstart: [...] services --disabled=avahi-daemon,gpm,haldaemon,kudzu,messagebus,netfs --enabled=ntpd,snmpd [...] %packages --nobase @core xen kernel-xen libvirt postfix ntp net-snmp sudo sysstat rsync tcpdump tcsh bzip2 man lsof smartmontools mailx screen vim-enhanced isns-utils iscsi-initiator-utils cryptsetup-luks vconfig acpid audit cpuspeed mdadm psacct xorg-x11-xauth edac-utils memtest86+ patch which yum-protectbase OpenIPMI OpenIPMI-tools %post touch /.autorelabel sed -i '/^\[/aprotect=1' /etc/yum.repos.d/CentOS-Base.repo cat << _EOF_ >> /etc/sysctl.conf net.core.rmem_max = 1048576 net.core.rmem_default = 1048576 net.core.wmem_max = 1048576 net.core.wmem_default = 1048576 vm.swappiness = 1 _EOF_ cat << _EOF_ > /etc/snmp/snmpd.conf [...] # This is so SNMP reports correct interface rates interface bond0 161 1000000000 interface bond0.10 135 1000000000 interface bond0.20 135 1000000000 interface bond0.30 135 1000000000 interface bond0.40 135 1000000000 interface bond0.101 135 1000000000 [...] _EOF_ sed -i 's/^[ \t]*LoginGraceTime.*/#&/g' /etc/ssh/sshd_config sed -i 's/^[ \t]*PermitRootLogin.*/#&/g' /etc/ssh/sshd_config sed -i 's/^[ \t]*MaxAuthTries.*/#&/g' /etc/ssh/sshd_config sed -i 's/^[ \t]*PasswordAuthentication.*/#&/g' /etc/ssh/sshd_config sed -i 's/^[ \t]*MaxStartups.*/#&/g' /etc/ssh/sshd_config cat << _EOF_ >> /etc/ssh/sshd_config LoginGraceTime 1m PermitRootLogin forced-commands-only MaxAuthTries 2 PasswordAuthentication no MaxStartups 2 _EOF_ sed -i 's#kernel /xen.*#& dom0_mem=2G#' /boot/grub/grub.conf sed -i 's#module /vmlinuz.*#& elevator=deadline#' /boot/grub/grub.conf cat << _EOF_ >> /etc/modprobe.conf alias bond0 bonding options bond0 mode=balance-rr miimon=100 updelay=1000 options netloop nloopbacks=64 options forcedeth max_interrupt_work=10 _EOF_ touch /etc/sysconfig/iptables sed -i -r 's/^IPTABLES_MODULES=.*/#&/' /etc/sysconfig/iptables-config sed -i -r '/^#IPTABLES_MODULES=.*/a \IPTABLES_MODULES=""' /etc/sysconfig/iptables-config cat << _EOF_ > /etc/sysconfig/network-scripts/ifcfg-bond0 DEVICE=bond0 BOOTPROTO=none ONBOOT=yes USERCTL=no _EOF_ cat << _EOF_ > /etc/sysconfig/network-scripts/ifcfg-bond0.10 DEVICE=bond0.10 BOOTPROTO=none ONBOOT=yes USERCTL=no VLAN=yes BRIDGE=br10 _EOF_ cat << _EOF_ > /etc/sysconfig/network-scripts/ifcfg-br10 DEVICE=br10 TYPE=Bridge BOOTPROTO=static BROADCAST=<xxx> IPADDR=<xxx> NETMASK=<xxx> NETWORK=<xxx> IPV6INIT=yes IPV6_AUTOCONF=yes ONBOOT=yes DELAY=0 STP=on _EOF_ sed -i -r '/^(HWADDR=|#)/!d' /etc/sysconfig/network-scripts/ifcfg-eth0 cat << _EOF_ >> /etc/sysconfig/network-scripts/ifcfg-eth0 BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes USERCTL=no _EOF_ sed -i -r '/^(HWADDR=|#)/!d' /etc/sysconfig/network-scripts/ifcfg-eth1 cat << _EOF_ >> /etc/sysconfig/network-scripts/ifcfg-eth1 BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes USERCTL=no _EOF_ sed -i -r '/^(HWADDR=|#)/!d' /etc/sysconfig/network-scripts/ifcfg-eth2 cat << _EOF_ >> /etc/sysconfig/network-scripts/ifcfg-eth2 BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes USERCTL=no _EOF_ sed -i -r '/^(HWADDR=|#)/!d' /etc/sysconfig/network-scripts/ifcfg-eth3 cat << _EOF_ >> /etc/sysconfig/network-scripts/ifcfg-eth3 BOOTPROTO=none ONBOOT=yes MASTER=bond0 SLAVE=yes USERCTL=no _EOF_ sed -i -r 's/(SYNC_HWCLOCK=).*/\1yes/' /etc/sysconfig/ntpd cat << _EOF_ > /root/xendomains.patch --- /etc/init.d/xendomains.dist 2008-11-04 09:57:48.000000000 -0600 +++ /etc/init.d/xendomains 2008-11-04 09:58:30.000000000 -0600 @@ -175,9 +175,9 @@ parseln() { - name=\`echo "\$1" | cut -c0-17\` + name=\`echo "\$1" | cut -d' ' -f1\` name=\${name%% *} - rest=\`echo "\$1" | cut -c18- \` + rest=\`echo "\$1" | cut -d' ' -f2-\` read id mem cpu vcpu state tm < <(echo "\$rest") } _EOF_ patch -p0 < /root/xendomains.patch mv /etc/xen/xend-config.sxp /etc/xen/xend-config.sxp.dist cat << _EOF_ > /etc/xen/xend-config.sxp # -*- sh -*- (xend-unix-server yes) (xend-unix-path /var/lib/xend/xend-socket) (xend-relocation-server yes) (xend-relocation-port 8002) (xend-relocation-address '<xxx>') (xend-relocation-hosts-allow '^localhost\$ ^localhost\\\\.localdomain\$ ^<xxx>\$') (network-script /bin/true) (vif-script vif-bridge) (dom0-min-mem 768) (dom0-cpus 1) (vncpasswd '') _EOF_ sed -i -r 's/^XENDOMAINS_SAVE=.*/#&/' /etc/sysconfig/xendomains sed -i '/^#XENDOMAINS_SAVE=/a \XENDOMAINS_SAVE=' /etc/sysconfig/xendomains rm -f /etc/libvirt/qemu/networks/autostart/default.xml mkdir /root/.ssh cat << _EOF_ > /root/.ssh/authorized_keys command="/usr/bin/virt-manager" ssh-rsa <xxx> <xxx> _EOF_ %end -- Christopher G. Stach II

1 0

Mixed dom0/domU usage?
by Dennis J. 04 Feb '09

04 Feb '09

Hi, I'm wondering about the impact of using both dom0 and domU's on a server at the same time. I'm worried about the performance impact of running a Mysql server in a domU and now I'm thinking about moving the Mysql part of a LAMP setup into dom0 and running a few Apache guests as domUs. Since the Apaches will serve mostly from an NFS share they won't have much impact on the disk i/o so the database should be able to utilize the local storage without much interference from the guests. The plan is to limit dom0 to let's say 4gb of ram and then use the rest of it for the VMs. Has anyone experinece with this kind of "mixed" setup (physical/virtual). Are there any known problems with this approach? Regards, Dennis

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