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2 participants
1612 discussions

Network failure on KVM guest
by lhecking＠users.sourceforge.net 04 Oct '12

04 Oct '12

I set up a KVM host a few months back with eight virtual machines running on it. Now, at least since yesterday, one of the guests (which apart from the MAC address is otherwise identical to six other guests) has lost its network connection. The other seven vms work fine. More bizarre, even rekickstarting does not work due to this issue. I suspect some issue on the host, but don't really have an idea what to check. Host and virtual machines all run CentOS6.3 plus all patches. The issue persists through a host reboot.

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SNMP monitoring
by Lars Hecking 03 Oct '12

03 Oct '12

It seems it's not possible to monitor kvm virtual image network interfaces via SNMP. MRTG's cfgmaker says ### The following interface is commented out because: ### * has no ifSpeed property and other monitors are consistently reporting that vm's interfaces are exceeding traffic thresholds (even on lo ...). Which is no surprise if the threshold is zero. I found a hint on some Debian forum that this behaviour is caused by the virtio driver. So I was wondering, is it recommended or are there advantages to configuring one of the emulated drivers instead (ne2k_pci,i82551,i82557b, i82559er,rtl8139,e1000,pcnet)? Or can I "fake it" somehow in the vm's snmpd config?

2 2

Why is SCSI disabled in kvm on CentOS 5.8?
by Bill Campbell 03 Oct '12

03 Oct '12

Looking at the SRPM kvm-83-249.el5.centos.5, and the SRPM for qemu-kvm-0.12.1.2-2.209.el6.src.rpm on CentOS 6.2, I see many patches to remove SCSI support. The 5.2 kvm.spec file disables scsi in the configure run. Why has this been disabled? Many old OS's don't grok SATA, but have had SCSI support for years. Bill -- INTERNET: bill(a)celestial.com Bill Campbell; Celestial Software LLC URL: http://www.celestial.com/ PO Box 820; 6641 E. Mercer Way Voice: (206) 236-1676 Mercer Island, WA 98040-0820 Fax: (206) 232-9186 Skype: jwccsllc (206) 855-5792 It does not require a majority to prevail, but rather an irate, tireless minority keen to set brush fires in people's minds. -- Samuel Adams

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Re: [CentOS-virt] centos 5.8 libvirt disk options
by Bill Campbell 28 Sep '12

28 Sep '12

I am attempting to use libvirtd/kvm on CentOS 5.latest to migrate a SCO OpenServer 5.0.6a VM from the old VMware server. I have converted the multiple vmdk disk files to a single file, then used qemu-img convert to create files for libvirtd, both qcow2 and raw formats. After many attempts to get this working I'm up against what appears to be a brick wall. + The VMware VMs are using straight 'ide' HD emulation which has been working well for several years. + The 'ide' on libvirtd appears to map to SATA which isn't supported by OSR5. I've tried doing a fresh install from CDROM, but the installation fails to find the hard disk. I might be able to find the appropriate BTLD for this, but that won't help migrating existing VMs. + When I tried using 'scsi' libvirtd says this isn't supported. This would be my preferred emulation as we have used SCSI drives since the early days of Xenix on Tandy hardware. + The final problem if these are solved is that SCO is funny about its drive geometry, and the current versions of libvirtd and qemu don't appear to support the <geometry> allowing one to specify heads, cylinders, etc. Am I going to have to resort to using VMware workstation for this? Bill -- INTERNET: bill(a)celestial.com Bill Campbell; Celestial Software LLC URL: http://www.celestial.com/ PO Box 820; 6641 E. Mercer Way Voice: (206) 236-1676 Mercer Island, WA 98040-0820 Fax: (206) 232-9186 Skype: jwccsllc (206) 855-5792 Good decisions should be rewarded and bad decisions should be punished. The market does just that with its profits and losses.

3 2

Walkthrough available for bonding, bridging, and VLAN's?
by Nico Kadel-Garcia 27 Sep '12

27 Sep '12

Silvertip257, when you did this CentOS 6/KVM/bonding/bridging, did you ever get all the parts playing together correctlhy? I'm facing a setup with only two NIC's, and need for multiple trunked VLAN access, and bonded pairs, and KVM based bridges to get the VM's with exposed IP addresses. I can get basically any 2 out of the 3 server network components working, binding, VLAN's, or KVM bridging, but attempts to pull all together on CentOS 6.3 fails. I'm finding numerous partial references, and a lot of speculation of "this setup should work!", but no cases of anyone actually doing it. And I'm unable to reach out to the upstream vendor directly until some paperwork gets straightened out. (And oh, I've been away from CentOS for a while, but am in the midst of deploying about 50 CentOS VM's on KVM virtualization if I can *get this working!!!!*)

2 1

How do boot a xen domu into run level 1
by me＠tdiehl.org 21 Sep '12

21 Sep '12

Hi, I have a C5.8 machine with several DomU's. I fubared the fstab on one of them and I need to get it into single user mode. Does anyone know how to do that? I tried adding single to the extras line in /etc/xen/machine_name but it still tries to start in level 3. To make things worse, the root partition is on LVM. Alternatively, does anyone know how to access the image from DomU? I tried to use kpartx but when I run VGscan, I do not get the lvm activated. Regards, -- Tom me(a)tdiehl.org Spamtrap address me123(a)tdiehl.org

3 6

KVM serial cards
by James B. Byrne 20 Sep '12

20 Sep '12

I am returning to an old question and am investigating whether or not the following device even exists. I would like to find a PCI or PCIe multi-port serial card that supports MSI or MSIx. Is there such a creature? -- *** E-Mail is NOT a SECURE channel *** James B. Byrne mailto:ByrneJB@Harte-Lyne.ca Harte & Lyne Limited http://www.harte-lyne.ca 9 Brockley Drive vox: +1 905 561 1241 Hamilton, Ontario fax: +1 905 561 0757 Canada L8E 3C3

1 0

Issues with routing IPv6 to KVM Guests
by David Hackl 20 Sep '12

20 Sep '12

Hi People, I have some issues with routing ipv6 to my kvm guests. I use a bridge interface with bridge-utils like recommended in the most howtos. Bridge conf: http://fpaste.org/hh9U/ ip -6 route show output: http://fpaste.org/c5Rd/ sysctl.conf: http://fpaste.org/oMjD/ Thanks for your help in advance. If you need more informations just let me know. David Hackl

3 7

CentOS 6 KVM guest on CentOS 5 host
by Jussi Hirvi 17 Sep '12

17 Sep '12

I have a KVM virtual stack of about 10 v-machines on a CentOS 5 host. Now the perceived efficiency of the whole virtual stack has dropped. The load averages may be low, but still the systems sometimes hang for even more than a minute. Apache does not serve, email is delayed, etc. I was wondering if there might be a connection with this: I recently added my first CentOS 6 guest to this virtual stack. Could a CentOS 6 guest somehow behave badly on a CentOS 5 host?? - Jussi

1 0

Buffered console with kvm ?
by Stephen Harris 16 Sep '12

16 Sep '12

My Centos 6 server acts as a KVM host for a number of guests. Each of these guests have been configured with a serial console so I can do things like virsh console test2 and get access to the console of that machine. However what would be really useful is if the console also had a "buffer" so that messages which appeared while I wasn't connected could still be seen (much in the way old-style serial-port terminal servers would buffer output). Is this possible, "natively" ? Otherwise I was thinking of doing something like running 'screen -d -m -S test2 virsh console test2' and then I can connect with "screen" But that doesn't feel as friendly. Any ideasor recommendations? -- rgds Stephen

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