[THIN] Re: quick question on virtualization platforms
- From: "Steve Greenberg" <steveg@xxxxxxxxxxxxxx>
- To: <thin@xxxxxxxxxxxxx>
- Date: Tue, 9 Sep 2008 15:09:00 -0700
This sounds fine, but what happens when you hit a peak in production and
more RAM is needed? To quote a wise man, "Virtualize, but don't OVER
Virtualize"
That is, I recommend allocating resources according to what you actually
have and need and not starving RAM, i.e. ballooning, or even oversubscribing
it because if you need it, you need it, that can only lead to problems in my
mind.
Rather than oversubscribe RAM, I would suggest you consolidate applications
into less OS instances and/or go with OS virtualization instead....
Steve Greenberg
Thin Client Computing
34522 N. Scottsdale Rd D8453
Scottsdale, AZ 85266
(602) 432-8649
www.thinclient.net
steveg@xxxxxxxxxxxxxx
-----Original Message-----
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On Behalf
Of Dave Mishchenko
Sent: Tuesday, September 09, 2008 2:40 PM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: quick question on virtualization platforms
I'd agree with Joe that you have to be careful with over committing
memory. If you push it to hard you end up with the memory being paged
which will slow down performance. But it is a useful feature that we'll
most likely see in the other hypervisors down the road (just like
Hyper-V will get live migration in W2K8 R2).
Consider a real simple example of a host with 8 GB. If you create 8
VMs with 1 GB RAM each, you won't be able to start all 8 at the same
time on Hyper-V since each must grab a GB of physical RAM. But if
those VMs are really only using about 512 MB each, then half of the
memory on the host is idle and that's where ESX has an advantage. I'm
not saying that 2x memory over commit is what everyone will get, but if
you're buying 4 or 5 hosts, you could end up not having to get one host
if you go with ESX.
A discussion of memory should also include transparent page sharing and
memory ballooning which also contribute to the ability of ESX to host
more VMs with the same amount of physical memory.
-----Original Message-----
From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On
Behalf Of Brian Ehlert
Sent: Tuesday, September 09, 2008 11:57 AM
To: thin@xxxxxxxxxxxxx
Subject: [THIN] Re: quick question on virtualization platforms
The only reason that I mention it is becuase there are a bunch of
VMWare pro folks out there that consider it a short coming of the
other platforms.
Frankly, arguments can be made all ways.
The hypervisor will slowly become a commodity driving the focus from
the hypervisor to other virtualization items and to the management
experience, which will become a more important differentiator (it is
currently a consideration).
And sooner or later that world will change as well - as standards come
into play that are currently still in flux.
On Tue, Sep 9, 2008 at 11:40 AM, Joe Shonk <joe.shonk@xxxxxxxxx> wrote:
> I wouldn't call oversubscribing the host's memory a plus. It's one of
those
> things you have to be really careful about.
>
> -----Original Message-----
> From: thin-bounce@xxxxxxxxxxxxx [mailto:thin-bounce@xxxxxxxxxxxxx] On
Behalf
> Of Brian Ehlert
> Sent: Monday, September 08, 2008 10:41 AM
> To: thin@xxxxxxxxxxxxx
> Subject: [THIN] Re: quick question on virtualization platforms
>
> IMHO:
>
> At this point in time (as things are changing) VMware has two plusses
> over the others in the current and immediate future:
> 1) host memory over-commitment
> 2) VM portability across hardware (as in all devices are 100% emulated
> thus no hardware redetection in the guest OS at all).
>
> I first cut my hypervisor teeth on ESX just prior to Virtual Center
> and even the advantage that Virtual Center gave VMware in the past
> couple years is quickly disappearing.
>
> The decision is quickly coming down to cost, features, and
familiarity.
>
> Do you really need VMotion? or is QuickMigration / Live Migration
good
> enough?
> Do you really need DRS? (many have it, few really _use_ it)
> Are you recommending VMWare just becuase you are familiar with it (and
> vice-versa)?
>
> Either way, the playing field of features is quickly flattening.
>
>
>
> On Mon, Sep 8, 2008 at 9:12 AM, Kevin Stewart
<kevin.g.stewart@xxxxxxxxx>
> wrote:
>> Gurus and associated experts,
>>
>> I work for a company with a HUGE investment in VMware ESX and I can
safely
>> say that I am very knowledgeable in the product(s). I now have an
>> opportunity to build a new virtualization infrastructure for another
> company
>> and I'm toying with the idea of stepping out of my comfort zone to
look at
>> products like XenServer, MS Hyper-V, or Virtual Iron. I understand
that
> this
>> is mainly a Citrix/RDP list, but I would also assume that many, or
most of
>> you, are experts in one VM solution or another. Can anyone with
experience
>> in VMware and one or more of the other products offer up your insite
into
>> the differences, strengths and weaknesses of each? All of the vendors
have
>> their own comparison models, so I'm really looking for personal
> experience.
>>
>> Thanks in advance.
>> K Stewart
>>
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