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From Dag Sonstebo <>
Subject Re: hypervisor choice
Date Mon, 13 Nov 2017 09:36:29 GMT
Hi Ron,

We regularly use CentOS6 and 7 for KVM, and have never had an issue with non-booting hosts
– but then again our workloads are lab and testing based hence seldom get upgraded and seldom
run for more than a few weeks.

Saying that – we only ever use the CentOS minimal install, never with GUI – as you say
it’s surplus to requirements in most situations and comes with a lot of baggage. If you
need GUI tools like virt-manager you can either run it on a remote host or do a minimal local
install and open it up over a SSH forwarded X11-session – which all in all means you don’t
have to install the full GUI on each host.

With regards to Ubuntu – Eric has given a good rundown (personally I have no issues with
Ubuntu – I just find CentOS simpler and reliable). 

Dag Sonstebo
Cloud Architect

On 10/11/2017, 19:37, "Eric Lee Green" <> wrote:

    On 11/10/2017 11:01 AM, Ron Wheeler wrote:
    > I have been using CentOS for a long time but they seem to have screwed 
    > up the recent updates to CentOS 7 to the point where after updating to 
    > the latest version (originally build 514 and now 683), the system no 
    > longer boots. I have to boot to build 327 which runs fine.
    > The idea of having a server that fails after updating is not in my 
    > comfort zone. 
    The other popular choice if you are using KVM on Linux is Ubuntu LTS. 
    The current LTS version is 16.04 which is supported until 2021. 
    Cloudstack runs fine on Ubuntu LTS, but configuring the network may be a 
    bit cumbersome for someone accustomed to the Centos 
    /etc/sysconfig/network-scripts mechanism.
    In my experience over the years Ubuntu has not been quite as stable as 
    Red Hat Enterprise Linux, *but*, that may have changed with RHEL7/Centos 
    7, where they appear to break things regularly between minor version 
    updates in order to "improve" the system. I, too, ended up with the 
    issue of one of my Centos 7 servers not rebooting after an update, and 
    having to boot it back to an older kernel. I ended up re-formatting and 
    re-installing that server entirely and restoring the system 
    configuration from backups.
    At this point I'd suggest remaining with KVM on Linux as your 
    hypervisor. It appears to perform better overall than Xen or vSphere and 
    the cost-effectiveness overall cannot be beat, especially if you are 
    buying hardware in bulk and using an automated mechanism to deploy your 
    hardware and the software load upon it so that you don't have to manage 
    it individually.
    If you are looking for overall reliability (at a cost), vSphere is of 
    course "the" reliable choice (I have some ESXi hosts that have been up 
    for over 500 days, and the last time they went down was during a planned 
    outage to rearrange the racks), but it is very picky about its hardware 
    and likely won't like your current hardware. It can also become somewhat 
    expensive as you add hosts to your vSphere cluster, which is the basis 
    of a CloudStack pod (rather than the individual hosts). It's also as 
    much as 10% slower by my measurements under many workloads because they 
    make numerous decisions that improve reliability at the expense of 
    performance. Still, for customers that value reliability above all else, 
    vSphere is a brick -- reliable and pretty much bullet-proof.
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