Hello,
I'm writing to you to request your permission to change the current VM system
on IND-PROD002 (the primary Indy Xeon server).
We currently run Hyper-V, as you probably know. I say we because I end up
helping Andrew quite frequently. I recommended this several months ago over
Xen, because we could not get Xen working properly (I take full responsibility
for that failure). This was due to several reasons:
1) I was sick with stomach flu around the time this happened. This seriously
impeded my ability to help.
2) We were using experimental stuff. Xen was experimental, the Linux kernel
used was experimental, it was all bleeding edge stuff; much of it was
untested.
3) I didn't understand much of this at the time. Andrew didn't either. I didn't
do my homework properly, which, for this, was a huge mistake.
I have, however rectified the above:
1) I am now completely better, minus a minor cold. I can actually do real work
again :D.
2) I'm now using stable stuff, tried and true. I've personally tested much of
this beforehand, as well as hundreds of others. Having learned my lesson, I
would not recommend software anymore unless I have personally tested it
thouorghly.
3) I've done my homework properly now. I have a pretty good grip on things. I've
spent about a month getting to know Xen and related things. I tested it
inside several VM's on the box and as well as a VM on my box.
You may be wondering, however. Why fix what isn't broken? Well, Hyper-V
currently has several issues, flaws that are fundamental problems with Hyper-V
and no fault of our own configuration. For example, mouse control doesn't work
in non-Windows VM's. This is a rather nasty limitation, one that does not exist
in Xen, and has irritated me and Andrew for quite some time. Disk I/O is also
becoming an extreme bottleneck. The FreeBSD VM has suffered from terrible disk
I/O lag spikes, bad enough to, in my personal opinion, seriously hamper the
usability of the VM. If the lag spikes get worse, the VM might not be able to
take the load anymore. My personal testing with Xen has shown that these disk
I/O issues do not exist with it at all.
Xen also has many more features. It is easy to tune VM paramaters with Xen
on-the-fly. For example:
root@shadow ~ # xm mem-set caspar 512
This command adjusts the amount of RAM the VM caspar has available to it. In
this case, it has been adjusted to 512 MB, all without restarting or shutting
down the VM. It's also easy to adjust the amount of CPU power each VM gets.
Xen's scheduling is also vastly superior to Hyper-V's. It always makes sure
each VM gets its fair share of CPU and I/O time. I have seen boxes out there
running only Core Duo CPU's and 6 GB RAM that easily handle 25 VM's. Considering
how poorly Hyper-V has scaled in my experience, I don't think it could handle
more than 15 or so.
I could give you a long list of other technical reasons why Xen is superior. I
came up with 12 off the top of my head when discussing this with Andrew. While
I doubt you would care about most of them, I am convinced that Xen is a very
compelling replacement for Hyper-V.
Now, what I am really requesting is a maintence window to get this all set up.
My time request is modest; only 3 hours on a weekend, from 3 AM to 8 AM, during
a low-use period. In addition, if Andrew backs everything up properly (which,
knowing him, he will), then we could easily revert (in short time) to the old
system if things aren't working according to plan.
All I'm asking is for a chance to get this working. Please let us give this a
second go :).
-- Jacob Myers