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How to build CentOS 7 AMI
by Alan Ivey 01 Feb '16

01 Feb '16

I'd like to revisit the thread about how the CentOS 7 AMIs are created ( https://lists.centos.org/pipermail/centos-devel/2015-July/013652.html) and see if the process can be published in the https://github.com/CentOS/sig-cloud-instance-build repository or another relevant location. With CentOS 7 AMIs only being available in the Marketplace, all resulting EC2 instances have the Marketplace codes attached to the EBS volumes. A significant restriction of this is that a resulting image cannot be the non-primary volume of an instance unless it is powered down. This presents itself to be a problem in at least the following scenarios: - Unable to attach a CentOS 7 boot volume to another instance for repair without either creating a temporary instance or shutting down an existing one. For example, if you messed up the /etc/sudoers file and logged out, and wanted to repair, you would not be able to repair by mounting to another instance and editing the file without incurring additional (albeit small) cost, or having an existing instance be temporarily unavailable. - The "amazon-chroot" Packer Builder ( https://www.packer.io/docs/builders/amazon-chroot.html) does not work because it starts by mounting a copy of the snapshot tied to the AMI as part of a scripted operation and therefore cannot power off to do so Custom AMIs, snapshots, copied EBS volumes, etc, all have the marketplace codes copied to them and inherit the restrictions. If an org was to use these features for automating environments and was disconnected from the original Marketplace agreement, they may be unaware of this limitation. I would also appreciate being able to have the additional transparency of seeing how an AWS AMI is created as the docker/openstack/etc images from the repository referenced above. This would be useful in environments with regulatory compliance concerns, such as AWS GovCloud, HIPAA, FedRAMP, etc. I understand the benefit that Marketplace registrations allow for the ability to notify users of any changes, and I am not necessarily advocating for switching away from the Marketplace as the primary AMI location. I would like to be provided the opportunity to build a private AMI in the exact same procedure as the official image so as to avert the restrictions provided by the Marketplace. Thank you, Alan

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hoping to reschedule SIG meetings to Tuesdays 1500 UTC
by Lokesh Mandvekar 26 Jan '16

26 Jan '16

I can't make it to the current schedule for alternate Tuesday 1400 UTC meetings. I was hoping we could reschedule it to 1500 UTC on the same Tuesdays instead, or any other slot which could work for all. What do other members think? -- Lokesh Freenode: lsm5 GPG: 0xC7C3A0DD

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LVM mirror database to ramdisk
by Ed Heron 24 Jan '16

24 Jan '16

I'm still running CentOS 5 with Xen. We recently replaced a virtual host system board with an Intel S1400FP4, so the host went from a 4 core Xeon with 32G RAM to a 6 core Xeon with 48G RAM, max 96G. The drives are SSD. I was recently asked to move an InterBase server from Windows 7 to Windows Server. The database is 30G. I'm speculating that if I put the database on a 35G virtual disk and mirror it to a 35G RAM disk, the speed of database access might improve. I use local LVM for my virtual disks with DRBD on top to mirror the disk to a backup server. If I change grub.conf to increase RAM disk size and increase host RAM, I could create a 35G RAM disk. I'd modify rc.local to add pvcreate /dev/ramdisk vgextend vg /dev/ramdisk lvconvert -m 1 --corelog vg/lv_database /dev/ramdisk Even with lv_database being 35G, it doesn't take long to activate the mirror. I haven't decided where to put the commands to turn off the lvm mirror. lvconvert -m 0 vg/lv_database vgreduce vg /dev/ramdisk pvremove /dev/ramdisk I haven't put this in real world use, yet. On it's face, this might speed up database access. Would we expect it to speed up database access in real world use? Should I document the process so others could know how to do this? I realize new documentation for CentOS 5 virtualization would be considered obsolete before I wrote it but I'm expecting to test CentOS 7 virtualization in the next few months and, when I am comfortable, I'd upgrade my 18 virtual hosts. I would update the documentation, at that time, as well.

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Hostname inside lxc container
by C. L. Martinez 22 Jan '16

22 Jan '16

Hi all, I have installed a CentOS6 lxc guest under a Debian 8.x LXC host. All it is working ok but I can't change the hostname for the centos6 lxc container (it is using the same hostname from Debian host). I have modifyed HOSTNAME under /etc/sysconfig/network and /etc/hosts file, but it doesn't works. Do I need to change anything else?? Thanks.

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DomU Guests not shutting down nicely when Dom0 Hypervisor shuts down
by Francis Greaves 21 Jan '16

21 Jan '16

I am using Xen 4.6.0-8.el7 on CentOS 7 with 3 Linux DomUs. I did have Xen 4.? on CentOS 6.5 on my previous system. I installed using yum install centos-release-xen. On shutting down the Hypervisor it used to wait for the DomUs to shut down gracefully (one can take a minute or more), then on starting up again it would restart the DomUs, all nice and controlled. For some reason the DomUs (CentOS or Ubuntu servers) are not shutting down nicely when the Hypervisor is shutdown, and not restarting. I have the cfg files in /etc/xen/auto so they should start up. If I forget to shut down the DomU guests then the shutdown hangs. I am running this on a Dell Poweredge T430 by the way. Any ideas why, and how to cure this?

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Re: [CentOS-virt] CentOS 6 Virt SIG Xen 4.6 packages available in centos-virt-xen-testing
by President 21 Jan '16

21 Jan '16

My .02 is to stay the course. As a server admin, I want to be able to type things like: yum upgrade php not yum upgrade php55-epel-rpmforge-fancy-package Having to remember all the idiosyncrasies of a system is what causes some type of major failure in the future whenever (1) you forget something or (2) someone else has to pick up the box to adminster. -- Craig Thompson, President Caldwell Global Communications, Inc. +1 (423) 559-5465 caldwellglobal.com -----Original message----- From: George Dunlap <dunlapg(a)umich.edu> Sent: Thursday 21st January 2016 7:32 To: Discussion about the virtualization on CentOS <centos-virt(a)centos.org> Subject: Re: [CentOS-virt] CentOS 6 Virt SIG Xen 4.6 packages available in centos-virt-xen-testing On Thu, Jan 21, 2016 at 12:01 PM, Peter <peter(a)pajamian.dhs.org> wrote: > On 15/01/16 05:57, George Dunlap wrote: >> As mentioned yesterday, Xen 4.6 packages are now available for >> testing. These also include an update to libvirt 1.3.0, in line with >> what's available for CentOS 7. Please test, particularly the upgrade >> if you can, and report any problems here. > > Per conversation in IRC, Xen 4.6 no longer includes xend and therefore > no longer has the "xm" command. This is problematic for people who may > be using xm in various scripts on their host (such as home-brewed backup > scripts). > > I think it's a bad idea to break this functionality without warning by > allowing a simple "yum update" to remove it. You will take a lot of > people by surprise and cause such scripts to stop working, if people are > running yum cron the situation becomes even worse. Thanks, PJ, for your input. Just to be clear: 1. In the Xen 4.4 packages (first released October 2014), xend was disabled by default; so anyone using xend at the moment has already manually intervened to enable deprecated functionality 2. In 4.4, the first time xm was executed, it printed this warning: --- xend is deprecated and scheduled for removal. Please migrate to another toolstack ASAP. See http://wiki.xen.org/wiki/Choice_of_Toolstacks for information on other alternatives, including xl which is designed to be a drop in replacement for xm (http://wiki.xen.org/wiki/XL). --- 3. ...and on every subsequent invocation, it printed this warning: "WARNING: xend/xm is deprecated" I think this constitutes "warning" that the functionality was going to break at some point. :-) Also, in most cases "s/xm/xl/g;" Just Works; most people have reported that changing from xm -> xl was pretty painless. So this isn't like upgrading from Python 2 to Python 3 (or QT 4 to 5, or...). > I think that due to this lack of backwards compatibility with Xen 4.4 > and earlier versions it would be a good idea to not force the upgrade on > people who are not wary of it. I propose that the new packages carry > the name "xen46" and they purposefully conflict with the old "xen" > packages. That will require people to take positive action to do the > upgrade and hence avoid breaking systems unintentionally. This would avoid breaking things for people still using xm, which certainly has some value. However it has some costs: * The packages between C6 and C7 will now be slightly different, increasing the maintenance burden. This is not only in the spec file, but also in all the associated scripting machinery for managing packages in the CBS and smoke-testing packages before pushing them publicly. * Instructions for installing Xen are now differend between C6 and C7, and slightly more complicated, as they have to explain about Xen 4.6 vs alternatives. * Users who have heeded the warning and switched to xl will have to make an extra effort to switch to Xen 4.6. If they don't follow centos-virt, they may not notice that there's a new package to upgrade to. I'm a developer, not a server admin, so I can't gauge how important this issue is. Before making such a change, I'd like to hear opinions from other people in the community about how important (or not) it is to avoid breaking xm, given the ample warning (>1 year) users have had. On the other hand, explicitly moving to a "xen${VER}" (both for C6 and C7) would make it simpler for people to step up and maintain older versions in parallel if anybody wanted to do so. Thanks again, Peter, for bringing this up. Peace, -George _______________________________________________ CentOS-virt mailing list CentOS-virt(a)centos.org https://lists.centos.org/mailman/listinfo/centos-virt

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Re: [CentOS-virt] DomU Guests not shutting down nicely when Dom0 Hypervisor shuts down
by Keith Roberts 21 Jan '16

21 Jan '16

Hi Francis. Personally I would gracefully shutdown all the VM’s first, before attempting to shutdown the xen hypervisor. Are you getting any fsck errors when restarting those VM’s? Kind Regards, Keith On 21 Jan 2016, at 08:48, Francis Greaves <francis(a)choughs.net> wrote: > I am using Xen 4.6.0-8.el7 on CentOS 7 with 3 Linux DomUs. I did have Xen 4.? on CentOS 6.5 on my previous system. I installed using yum install centos-release-xen. > On shutting down the Hypervisor it used to wait for the DomUs to shut down gracefully (one can take a minute or more), then on starting up again it would restart the DomUs, all nice and controlled. > For some reason the DomUs (CentOS or Ubuntu servers) are not shutting down nicely when the Hypervisor is shutdown, and not restarting. I have the cfg files in /etc/xen/auto so they should start up. > If I forget to shut down the DomU guests then the shutdown hangs. > I am running this on a Dell Poweredge T430 by the way. > Any ideas why, and how to cure this? > _______________________________________________ > CentOS-virt mailing list > CentOS-virt(a)centos.org > https://lists.centos.org/mailman/listinfo/centos-virt

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20 Jan '16

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by meows＠techie.com 20 Jan '16

20 Jan '16

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Xen kernel-3.18.25-17 EL6 and EL7 needs testing
by Johnny Hughes 20 Jan '16

20 Jan '16

There is a new xen kernel for centos-6 and centos-7 the needs testing in: http://cbs.centos.org/repos/virt6-xen-common-testing/x86_64/os/Packages/ and http://cbs.centos.org/repos/virt7-xen-common-testing/x86_64/os/Packages/ Thanks, Johnny Hughes

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