On 03/27/2011 09:00 AM, Jerry Franz wrote:
On 03/27/2011 02:57 AM, Jussi Hirvi wrote:
Some may be bored with the subject - sorry...
Still not decided about virtualization platform for my "webhotel v2"
(ns, mail, web servers, etc.).
KVM would be a natural way to go, I suppose, only it is too bad CentOS 6
will not be out in time for me - I guess KVM would be more mature in
CentOS 6.
Any experience with the free "VMware vSphere Hypervisor"?. (It was
formerly known as "VMware ESXi Single Server" or "free ESXi".)
http://www.vmware.com/products/vsphere-hypervisor/overview.html
I would need a tutorial about that... For example, does that run without
a host OS? Can it be managed only via Win clients? Issues with CentOS
4/5 guests (all my systems are currently CentOS 4/5).
I'm currently using Ubuntu Server 10.04-LTS as a host for KVM running
CentOS5.5 guests I migrated from VMware Server 2. Works fine. A nice
feature of current generation KVM is that you are supposed to be able to
do live migration even without shared storage (although I haven't tested
that yet). I wrote some custom scripts to allow me to take LVM snapshots
for whole-image backups and I'm pretty happy with the who setup.
The only corners I encountered were
- A lack of documentation on how to configure bridging over bonded
interfaces for the host server. It turned out to be fairly easy - just
not clearly documented anyplace I could find.
- The default configuration for rebooting/shutting dow the host server
just 'shoots the guests in the head' rather than having them shutdown
cleanly.:( You will want to write something to make sure they get
shutdown properly instead.
Once in a while I find it's useful to compromise just a little, so I use
Scientific Linux 6 as the Host OS, and run a bunch of CentOS-5.5 Guest
VMs. It all simply works.
KVM has improved quite a bit, and the management tools work well. One
thing that requires a bit of skill is getting bridging configured (which
I simply did by hand from the RHEL-6 documentation).
I'm happy with the result, and see no reason to replace the underlying
SL-6 Host distro.
SL-6 as the Host is rather slow to shut down gracefully and reboot,
because it hibernates the Guest OSs, one at a time, rather than just
killing them. Hibernation takes a while to write out to disk if you've
assigned a lot of RAM to the Guests. Bootup has to restore the saved
state, so that's a bit slow too. But it works very well.
I use partitionable RAID arrays for the Guests, and assign a "raw" md
device to each one rather than using the 'filesystem-in-a-file' method.
It seems to be a bit faster, but there's a learning curve to
understanding how it works.
One thing I found a bit annoying is the very long time it takes for a
Guest to format its filesystems on the RAID-6 md device assigned to it.
That's mostly due to array checksum overhead. RAID-10 would be a
*lot* faster but somewhat less robust ... you pick what's best for your
own situation.
Chuck