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==== LXC Linux Containers ====

Ok, virtualization again. Trying this approach on a Dell PowerEdge 2950.

  * https://linuxcontainers.org/
  * http://docs.oracle.com/cd/E37670_01/E37355/html/ol_config_os_containers.html
  * http://wiki.centos.org/HowTos/LXC-on-CentOS6

Starting with the latter.

When you get the SElinux policy, create the *.te file then

<code>

[root@petaltail ~]# vi lxc.te
[root@petaltail ~]# semodule -l | grep lxc
[root@petaltail ~]# checkmodule -M -m -o lxc.mod lxc.te
checkmodule:  loading policy configuration from lxc.te
checkmodule:  policy configuration loaded
checkmodule:  writing binary representation (version 10) to lxc.mod
[root@petaltail ~]# semodule_package -o lxc.pp -m lxc.mod
[root@petaltail ~]# semodule -i lxc.pp
[root@petaltail ~]# semodule -l | grep ^lx
lxc     1.0

</code>


Ah, I'm simply going to CentOS-7 because LXC is fully integrated 
  * [[http://www.theregister.co.uk/2014/07/07/centos_7_gm/]]

Ah, no.  Took a look at v7 and it's very different with the over engineering part of system control.  Will learn later, back to v6.5. I also want to preserve the ability to run different OS flavors which is not possible under LXC containers.

==== KVM ====

KVM is hardware level virtualization as opposed to my previous meanderings into the world of software level virtualization (Xen [[cluster:127|Virtual HPCC services]]).  There is basically a "dom0" domain manager running keeping track of virtual images that run from block devices written onto a block device.

  * Followed the primary setup on this page
    * http://www.howtoforge.com/virtualization-with-kvm-on-a-centos-6.4-server
  * Once ''virt-manager'' worked we followed this doc a bit setting up bridges etc
    * http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDQQFjAB&url=http%3A%2F%2Flinux.dell.com%2Ffiles%2Fwhitepapers%2FKVM_Virtualization_in_RHEL_6_made_easy.pdf&ei=GZfjU9P2KqS-sQS5p4HgCw&usg=AFQjCNFgCfRXV-g4eGE_Fm5AiIw4thnfYg&bvm=bv.72676100,d.cWc&cad=rja
      * for future reference, more details
        * http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CC4QFjAA&url=http%3A%2F%2Flinux.dell.com%2Ffiles%2Fwhitepapers%2FKVM_Virtualization_in_RHEL_6_Made_Easy_Part2.pdf&ei=GZfjU9P2KqS-sQS5p4HgCw&usg=AFQjCNGzBgZ3f-YvCbV5sav7450BX_Io6Q&bvm=bv.72676100,d.cWc&cad=rja
  * But once I got to the cloning part, I found this to be super easy and scritpable
    * http://rwmj.wordpress.com/tag/virt-clone/

First I create my v1 clone with virt-install then build my v1 clone the way I wanted it and then customized it manually (/etc/fstab, openlava scheduler, /etc/passwd, /etc/shadow, /etc/group and /etc/hosts, etc). Added a second bridge (''br1'' is public/internet, previously created ''br0'' is for private network for scheduler).  That was done via virt-manager GUI (View VM Details of vm and then select Add Hardware). ''br1'' allows me to run yum update before I clone. Power this clone up, add to a test queue, and submit some jobs to make sure it all works.  Then clone.

<code>

# create v1, my "base" clone: 8 gb hdd, 1 gb ram, centos 6.5, connect to ethernet bridge ''br0''

virt-install --connect=qemu:///system -n v1 -r 1024 --vcpus=1 \
--disk path=/var/lib/libvirt/images/v1.img,size=8 \
-c /var/lib/libvirt/images/CentOS-6.5-x86_64-bin-DVD1.iso \
--vnc --noautoconsole --os-type linux --os-variant rhel6 --accelerate \
--network=bridge:br0 --hvm

</code>

Here are the steps for cloning v1 to v5. You'll need ''guestfish'' part of the libguestfs tools allowing you to edit content inside the block level file.  Very nifty.

  * yum install libguestfs-tools-c

Next we'll create the v5.img block device, dump the v1 config into v5.xml and then edit that file. UUID and Mac Address we'll edit and the last 2 characters we change to '05' (make it unique). Name becomes v5 from v1 and we'll similarly adjust the block device location/filename. Then we define this as domain v5.

Launch ''guestfish'' and make the same edits to Mac Address in files listed below. Then boot the vm.

<code>

# cd /var/lib/libvirt/images
# dd if=v1.img of=v5.img bs=1M

# virsh dumpxml v1 > /tmp/v5.xml
# vi /tmp/v5.xml
(change name, uuid, file location, mac address(es))

# virsh define  /tmp/v5.xml
Domain v5 defined from /tmp/v5.xml

# guestfish -i -d v5

Welcome to guestfish, the libguestfs filesystem interactive shell for
editing virtual machine filesystems.

Operating system: CentOS release 6.5 (Final)
/dev/vg_v1/lv_root mounted on /
/dev/sda1 mounted on /boot

><fs> edit /etc/sysconfig/network
(change hostname)
><fs> edit /etc/sysconfig/network-scripts/ifcfg-eth0
><fs> edit /etc/sysconfig/network-scripts/ifcfg-eth1
(for nics comment out any UUID lines, change hardware address, change IP)
><fs> edit /etc/udev/rules.d/70-persistent-net.rules
(change hardware address)
><fs> exit

# virsh start v5
Domain v5 started

</code>

==== Tests ====



^ Melt Lammps LJ problem, 10000 steps with 32000 atoms Loop Times (secs) ^^^^^^^^^
|  2  |  4  |  6  |  8  |  10  |  12  |  14  |  16  |  nr of jobs  |
|  556  |  560  |  588  |  625  |  760  |  936  |  1122   |  1300  |    |
|  (linear)  ||||  781  |  938  |  1094  |  1250  |    | 
|  (n35:load 32)  ||||  726  |    |    |    |    |
|  (hyperthreading)  ||||    |    |    |  ????  |  16 logical cores  |


16 VMs running in queue ''testvm'' on dual quad core PE2950 (8 cores, 16 GB ram)

  * First ran on n35 (32 core node under hyperthreading will full load) with an average loop time 726 secs.
  * As I submit jobs to the VMs they perform well up to 8 jobs (one job per core; dual quad core node).
    * That is with the KVM overhead
  * Assuming a linear penalty for over committing, 16 jobs is expected to take Loop times of 1250 secs.
    * However after 10 jobs we're surpassing that penalty threshold
  * And then I was to turn on Hyperthreading creating 16 logical cores
      * To my dismay this chipset does not support that, bummer!
      * Was expecting to gain some performance back ...
      * Maybe try on newer hardware when idle ...

But we learned Xen and KVM setups, and

  - We can now support a heterogeneous environment if we wanted (Suse, Scientific Linux, Windows (eh, what?))
  - Use a KVM environment up to the number of cores on a box without penalty
  - And change the mix of nodes if needed (more/less cores per node, memory size etc)
  - Still, not an answer for my "high core count/low memory footprint" problem, see [[cluster:133|high core count/low memory footprint]]

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