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CentOS 5.9 Xen DomU NFS Data Transfer to Dom0 kills network.
by Veli-Pekka Kestilä 06 Mar '13

06 Mar '13

Greetings, I have problem using Dom0 as NFS(v4)-server and DomU as client. When ever the client actually tries to copy data to nfs-server the virtual network (bridge) between the two hosts completely freezes and stops working. After this of course the client hangs waiting nfs-server to answer and server continues to try to contact nfslock daemon on the client. Dom0 is still accessible from outside trough virbr0 which the client doesn't have access. The problems only come on data transfer as making directories and removing them and doind ls works fine before one tries to transfer data. Anyone have suggestion what could fix this behavior. Veli-Pekka

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Re: [CentOS-virt] Time
by James B. Byrne 17 Feb '13

17 Feb '13

On Wed, January 2, 2013 12:51, SilverTip257 wrote: > On Wed, Jan 2, 2013 at 9:41 AM, James B. Byrne > <byrnejb(a)harte-lyne.ca>wrote: > >> >> I ran into this situation several times whilst testing KVM and the >> lessons I learned from the experiences can be summarized as: >> >> 1. Never allow the kvm hypervisior to handle guests during a host >> shutdown. Use 'virsh shutdown' on each of the guests first and then >> shutdown the host. Use autostart to restart guests on a host's >> reboot. Write a script to process 'virsh list' to feed active >> domains >> to 'virsh shutdown' if automation is required and link that to >> /etc/rc0.d/K10<whatever>. >> >> > @James: Can you specifically cite why you manually power down each > node? Have you tried tweaking your libvirt settings in the config > file I noted in my earlier response to Robert? Two reasons. First, I am minimally familiar with kvm. The niceties of the options for it is beyond my kin for the nonce. Second, libvirt does not always work. I have had guests refuse to either suspend or shutdown from an automatic request to do so. When shutdown is done manually one discovers right away that there is a problem and which guest is causing it. > Set up a central NTP server and have your hosts (and not just VMs) > connect to it. It could be the VM host, but doesn't need to be. > Distribute the load to your NTP server and off of the public NTP pool > by running an NTP server for your servers to poll [0] ... it's a good > practice and everybody is happy. > I do that as well. However, I run one on each host just to serve its own guests and configure the host to run off our central ntp server. > > >> 4. On each guest have a cron job that checks for ntpd at regular >> intervals which reports failures and restarts the time service as >> necessary. We use: >> JOBNAME="Check ntpd status and restart if required" ; \ >> ntpstat > /dev/null && \ >> if [[ $? -gt 0 ]]; then /sbin/service ntpd start; fi >> >> > Why not configure the ntpd daemon and stick with that? > It does update on its own [1]. And ntpstat prints out the interval, > which matches the one mentioned at [1]. > I don't believe the ntpstat script/job is necessary (I've never had to > do more than set ntpd to run after configuring the servers it should > poll). > You misunderstand the purpose of the job. Netstat checks to see if the daemon is actually running. If it is not then netstat returns a non-zero exit code. If the ntpstat exit code is not zero then the service script is invoked to restart it. Additionally, netstat writes out to stderr that it could not find the daemon which gets emailed to support. I probably should have used [[ ! $? -eq 0 ]] but what I have written does work. We found ntpd just stoped on some guests upon occasion without any visible trace of a cause. Not frequently but when it did happen it was a nuisance to detect before clock drift on the guest caused some failure or other. This job detects these occurrences and self corrects. These are all CentOS-6.3 hosts and guests. -- *** 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

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Replacement for virt-manager
by Andrea Chierici 11 Feb '13

11 Feb '13

Hi, I have more than 20 VM in production with a shared storage and 6 blades as HV. Things begin to look confusing within virt-manager since there is no way to display only the powered-up nodes (the migrated and switched off machines appear on every hv entry). I wonder if there is something different and more appealing than virt-manager to manage such an infrastructure. My requirement are: be able to switch back to virt-manager whenever I want do not require switching nodes off, reboots, or any kin of intervention on VMs be open source be stable Anyone can suggest something? 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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Can't build 5.9 with KVM on a 6.3 host - DHCP hang?
by Stephen Harris 08 Feb '13

08 Feb '13

During the build (via a serial console) we get input: ImExPS/2 Generic Explorer Mouse as /class/input/input1 running install... running /sbin/loader Sending request for IP information for eth0... Determining host name and domain... Sending request for IP information for eth0... Determining host name and domain... And there it hangs. On the 6.3 host: Feb 8 08:28:55 penfold dhcpd: DHCPDISCOVER from 52:54:00:5a:a7:48 via br0 Feb 8 08:28:56 penfold dhcpd: DHCPOFFER on 10.0.0.205 to 52:54:00:5a:a7:48 via br0 Feb 8 08:28:56 penfold dhcpd: DHCPREQUEST for 10.0.0.205 (10.0.0.134) from 52:54:00:5a:a7:48 via br0 Feb 8 08:28:56 penfold dhcpd: DHCPACK on 10.0.0.205 to 52:54:00:5a:a7:48 via br0 Feb 8 08:28:56 penfold dhcpd: DHCPDISCOVER from 52:54:00:5a:a7:48 via br0 Feb 8 08:28:56 penfold dhcpd: DHCPOFFER on 10.0.0.205 to 52:54:00:5a:a7:48 via br0 Feb 8 08:28:56 penfold dhcpd: DHCPREQUEST for 10.0.0.205 (10.0.0.134) from 52:54:00:5a:a7:48 via br0 Feb 8 08:28:56 penfold dhcpd: DHCPACK on 10.0.0.205 to 52:54:00:5a:a7:48 via br0 I wonder if this could be related to the "renew" problem I'm seeing on a pre-existing 5.9 machine: Feb 8 07:00:11 mercury dhclient: DHCPREQUEST on eth0 to 10.0.0.134 port 67 (xid=0x4e88b5e5) Feb 8 07:00:55 mercury dhclient: DHCPREQUEST on eth0 to 10.0.0.134 port 67 (xid=0x4e88b5e5) Feb 8 07:00:55 mercury dhclient: 5 bad udp checksums in 5 packets Feb 8 07:01:02 mercury dhclient: DHCPREQUEST on eth0 to 10.0.0.134 port 67 (xid=0x4e88b5e5) Feb 8 07:01:14 mercury dhclient: DHCPREQUEST on eth0 to 10.0.0.134 port 67 (xid=0x4e88b5e5) Feb 8 07:01:49 mercury dhclient: 5 bad udp checksums in 5 packets It eventually gets there... Feb 8 07:02:00 mercury dhclient: DHCPREQUEST on eth0 to 10.0.0.134 port 67 (xid=0x4e88b5e5) Feb 8 07:02:00 mercury dhclient: DHCPACK from 10.0.0.134 (xid=0x4e88b5e5) Feb 8 07:02:00 mercury dhclient: bound to 10.0.0.135 -- renewal in 18554 seconds. My 6.3 new builds work just perfect; it's only 5.x that has problems! Any ideas? -- rgds Stephen

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Re: [CentOS-virt] cloud-init in CentOS 6.3 images
by Mathews, Bruce 08 Feb '13

08 Feb '13

Hi Karanbir, Thanks so much for your dedication and assistance! Glenn has been working in background to obtain a response to your query. Phillip will be reaching out to you directly in the near term to discuss in more detail. The Very Best! Bruce Basil Mathews HP Cloud Services, DBaaS Architect Hewlett-Packard Company +1 760 961 7699 / Tel +1 760 553 3197 / Mobile bruce.mathews(a)hp.com / Email 12386 Pocomoke Road Apple Valley, CA 92308 USA HP Public Cloud Site: http://www.hpcloud.com 'All the world is a stage, and all the men and women in it, merely players' Jaquis, As You Like It! Please consider the environment before printing this email. -----Original Message----- From: Karanbir Singh [mailto:kbsingh@centos.org] Sent: Friday, February 08, 2013 11:33 AM To: Discussion about the virtualization on CentOS Cc: Mathews, Bruce; Ferguson, Glenn (Cloud Services) Subject: Re: [CentOS-virt] cloud-init in CentOS 6.3 images On 02/08/2013 07:24 PM, Mathews, Bruce wrote: > Linux: > CentOS 6.2 Server 64 bit > CentOS 5.6 Server 64 bit This is what we want to fix ( where we == CentOS Project ). You should not be shipping images that are so far out of date. that 5.6 Server image is based on code that was released in Sept 2011. How can we fix this ? And this isnt really fixed by the users being able to bring in their own images, this really needs addressing at the hpcloud.com level. From our end, I am willing to do whatever is needed to make things work, you just need to not make it as painful as its been in the past. Regards -- Karanbir Singh, The CentOS Project +44-207-0999389 | http://www.centos.org/ | twitter.com/CentOS GnuPG Key : http://www.karan.org/publickey.asc

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Virtualisation, guests cached memory and density
by Nux! 08 Feb '13

08 Feb '13

Hello, We all know linux distros will use most of the free memory available for caching stuff, I/O buffers etc (hence sites like linuxatemyram.com) In many virt scenarios we have some sort of memory deduplication mechanisms, such as KSM on KVM (don't know how it's called in Vmware). My situation is one where I need to cram up as many virtual machines as I can on a single hypervisor and I believe KSM does not work for the memory used as cache/buffers. How could I work around this? Any other pointers for achieving higher density welcome (don't suggest container technology please). -- Sent from the Delta quadrant using Borg technology! Nux! www.nux.ro

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cloud-init in CentOS 6.3 images
by Brian Lalor 08 Feb '13

08 Feb '13

Good evening, all. I just tried spinning up a CentOS instance in EC2 using ami-de5bd2ee from the AWS marketplace. I put a dummy script into the user-data field when launching the instance from the EC2 console but found it didn't work, even though the SSH key for the root user did. I pinged Karanbir on ##aws and he suggested I post here to get the conversation started. I'm currently looking into what it takes to roll my own AMI; I've already invested a fair bit of work into creating packages and Puppet config based on a CentOS 6.3 system (mainly with Vagrant), and my initial test with Amazon's Linux AMI wasn't promising. I think execution of the user-data script is a must-have, as it's the only way to automate the creation of a new instance without external tools. Thanks, Brian

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CentOS AWS images in Sydney
by Karanbir Singh 08 Feb '13

08 Feb '13

hi Guys, We've been waiting on the AWS-MP services ( therefore the CentOS images ) to become available in Sydney but thats not happened yet and the messages from AWS are still the same : 'soon'. In the interim, should we just go ahead and make them availble via our account ? Regards -- Karanbir Singh +44-207-0999389 | http://www.karan.org/ | twitter.com/kbsingh GnuPG Key : http://www.karan.org/publickey.asc

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KVM virtio block layer - is TRIM/DISCARD supported?
by Dmitry E. Mikhailov 02 Feb '13

02 Feb '13

Hi, One question please: If I use SSD as a storage on a host machine, does KVM's virtio I/O layer pass the TRIM/DISCARD commands to the SSD? I guess the question would be twofold: 1) is TRIM supported/forwarded if only one LVM'ed partition of SSD is forwarded? 2) is TRIM supported/forwarded if full SSD is forwarded (i.e. /dev/sdX) -- Best regards, Dmitry Mikhailov

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Instance-backed CentOS AWS AMIs?
by Michael Militzer 02 Feb '13

02 Feb '13

Hi list, I've noticed that instance-backed AMIs are not available in AWS MP (only the EBS ones are there). Still though, also the instance-backed AMIs are listed as published and available on your wiki: http://wiki.centos.org/Cloud/AWS I've seen that the same question was asked already before but I'm not sure the answer given actually covered the whole question: http://lists.centos.org/pipermail/centos-virt/2013-January/003136.html I take from the discussion that the AWS MP publishing process is out of your control because it's handled by AWS people and may therefore also introduce some delay. But the initial question was more than a month ago and instance-backed AMIs are still not available in AWS MP - so did something go wrong here that caused the instance-backed AMIs to not get published? And if not through MarketPlace, is there some alternative way to obtain your instance-backed AMIs? We highly appreciate your cloud efforts and would really like to use your AMIs... Thanks, Michael

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