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1612 discussions

Qcow files
by mattias 07 Aug '13

07 Aug '13

I have a qcow file It shows correct size on one server Fdisk -l w.qcow 70 GB On the other server Fdisk w.qcow 0 MB stupid

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safety of LVM backups
by Rajagopal Swaminathan 06 Aug '13

06 Aug '13

Greetings, Can anybody confirm the safety of LVM snapshot backout (not a backup -- but similar to snapshot restore) for a VM? I understand that there is a step for restart of the CM and not live migration. Will any thing of rsync will help considering a usage of DD on various VM file formnats and various *visors(s)? Or is there a suggested (best practices) way of coelsing VMs snapshots and and possibily running a particular snapshot being coelesed? -- Regards, Rajagopal

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vmdk
by mattias 06 Aug '13

06 Aug '13

i try to use a older vmdk image on kvm it seems to work on a debian kvm box but not on a centos 6 box the kvm on centos says no bootable device but on debian it boots fine

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AWS AMI questions
by CS 01 Aug '13

01 Aug '13

Hi folks, I had a few questions in regards to the CentOS AMI: Are there instance backed versions of the AWS marketplace CentOS builds? It looks like there might have been at one point, but I'm not seeing them now, and since they're marked as being from the marketplace we're having some difficulties attaching the volumes to another system to create an instance backed version of it. Any ideas? Is it possible to download the AMI from somewhere and re-upload them so they don't have the Marketplace restrictions? I checked cloud.centos.org, but it seems like they files there haven't been updated in a while. It's my understanding that projectraindrops.net was used to build the AMIs, is it possible to run that service locally? Thanks! cs

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recover a imagefile
by mattias 31 Jul '13

31 Jul '13

i have a converted img file format i think are raw it are converted from qcow2 are it possible to convert it back to qcow2? i tryed with qemu-img convert -O qcow2 w.img w.qcow2 w.img are 75 gb fdisk w.img -l shows correct size but fdisk -l w.qcow2 shows totaly wrong! 0 mb

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Xen kernel fixes
by David Vrabel 24 Jul '13

24 Jul '13

Hi, I have made the for-centos-v5 branch available on git://xenbits.xen.org/people/dvrabel/linux.git This is based on 3.4.54 and includes the following additional fixes (since the for-centos-v4 branch). * x86/xen: during early setup, only 1:1 map the ISA region Fixes a boot failure if tboot is used. * xen/evtchn: avoid a deadlock when unbinding an event channel Fixes a potential deadlock by users (e.g., qemu, xenstored) of /dev/xen/evtchn. You may also wish to consider enabling CONFIG_XEN_BALLOON_MEMORY_HOTPLUG. The kernel bug that was causing problems is already fixed (by xen/balloon: Subtract from xen_released_pages the count that is populated) and now that dom0 will not try to auto-balloon by default, enabling this option should no longer cause problems in dom0. This option is required to increase the amount of memory in a guest using this kernel above the initial amount. David

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KVM, virtualized interface, dropped packets.
by Rafał Radecki 20 Jul '13

20 Jul '13

Hi All. I have currently a small problem to solve. I have a kvm virtual machine which in output of ifconfig eth0 | egrep 'RX packets|TX packets' RX packets:792681304 errors:0 dropped:560728 overruns:0 frame:0 TX packets:716661674 errors:0 dropped:0 overruns:0 carrier:0 show dropped packets. I think that rx buffer is to small (no strange messagess in dmesg) and would like to make it larger. But when I try a solution from http://www.scottalanmiller.com/linux/2011/06/20/working-with-nic-ring-buffe… I get: ethtool -g eth0 Ring parameters for eth0: Cannot get device ring settings: Operation not supported So what is the proper way to make rx buffers larger in this situation? Best regards, Rafal Radecki.

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Xen Balloon Driver on PVHVM CentOS6
by Rushikesh Jadhav 18 Jul '13

18 Jul '13

Hi List, I'm trying to work out the balloon driver on CentOS6 HVM but it seems to be not working with default 2.6.32 or newer 3.4 kernel. Does balloon driver work on HVM linux guests with Linux Kernel 3.4 from centos repo ? PV is fine and is able to balloon. My host is Xen 4.1.2 with dom0 as 3.4.46-8.el6.centos.alt.x86_64 My guest is CentOS6.4 with kernel 3.4.46-8.el6.centos.alt.x86_64 Please have a look at below guest logs, [root@hvmc6 ~]# uname -a Linux hvmc6 3.4.50-8.el6.centos.alt.x86_64 #1 SMP Fri Jun 21 03:14:22 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux [root@hvmc6 ~]# xenstore-ls memory initial-reservation = "1193984" initial-target = "1048576" static-max = "16777216" target = "1048576" dynamic-min = "1048576" dynamic-max = "1048576" memory-offset = "-258100" [root@hvmc6 ~]# dmesg | grep -i balloon xen/balloon: Initialising balloon driver. xen-balloon: Initialising balloon driver. [root@hvmc6 ~]# free -m total used free shared buffers cached Mem: 463 221 241 0 24 13 -/+ buffers/cache: 184 278 Swap: 9987 7 9980 When I try to set it manually from host, I get # xl mem-set 229 2049 xc: error: do_memory_op: WARNING: op=16 not converted to safe ioctls: Internal error Anyone has made CentOS6 PVHVM work with ballooning on Xen ? Thanks. Rushikesh

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Would a hardware TRNG benefit VMs?
by Digimer 17 Jul '13

17 Jul '13

Hi all, I've been curious about using hardware true random number generators in my VM clusters. This got me wondering about the VM's /dev/random source... If I setup a hardware TRNG on the host, would the VM's also benefit from it? Thanks! -- Digimer Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is trapped in the mind of a person without access to education?

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No eth0 in dom0 after installing xen
by Mark Nejedlo 16 Jul '13

16 Jul '13

I've just installed CentOS 6.4 an Xen on a new system, and eth0 is not found on dom0 when booting into Xen. When I boot into the 2.6.32 kernel outside Xen my network interface is found, using the e1000e driver. If I boot into Xen eth0 is not found, even if I modprobe the e1000e driver by hand. My NIC is an Intel I217-V. Any suggestions for things I can do to get my network working inside Xen? Thanks, Mark

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