[AusNOG] Back of envelope II

Fri Mar 6 14:20:46 EST 2009

I disagree.  There are some services/applications that lend themselves to clustering and many which do not unless a lot of expensive is involved.  Windows Servers, Citrix, Oracle and other DB servers, Exchange and so on are not easy to provide hardware redundancy without significant cost.

I don't think the costs of VMware are that excessive.

http://store.vmware.com/DRHM/servlet/ControllerServlet?Action=DisplayProductDetailsPage&SiteID=vmware&Locale=en_US&Env=BASE&productID=83617500

VMware Infrastructure Foundation Acceleration Kit for 6 Processors (VI Foundation, vCenter Server Foundation) + Gold (12x5) 1 Year Support US$3624 / AU$6194

Gives you everything you want.  Not free no, but very reasonably priced for what you get.

I so agree however, if the application is simple and can be dealt with by load balancer or reverse proxy, such as web hosting, smtp or other simple solutions, then that is the way to go.

...Skeeve

--
Skeeve Stevens, CEO/Technical Director

> -----Original Message-----
> From: Nathan Gardiner [mailto:ngardiner at gmail.com]
> Sent: Friday, 6 March 2009 1:56 PM
> To: Skeeve Stevens
> Cc: ausnog at ausnog.net
> Subject: Re: [AusNOG] Back of envelope II
>
> VMWare ESX is an expensive way to achieve server redundancy, if that's
> your only goal. SAN redundancy can be achieved through multipath on
> linux with equivalent solutions on Windows. Network redundancy can be
> achieved through bonding or teaming of NIC adaptors.
>
> The equivalent of what you are achieving through virtualisation is
> possible by deploying several hosts with the same function and using
> content switches, or even OSPF/anycast, to allow a single node to be
> taken down without (any/much) operational impact. Shared SAN storage
> and clustered filesystems can allow several nodes (with the correct
> application intelligence) to access the same data volumes.
>
> Virtualisation works well and reduces cost, but is not without
> limitation. High network utilisation can saturate shared network
> connections, high CPU can cause latency across the host, high SAN
> utilisation can cause storage latency. High memory utilisation can
> cause swapping, which in turn causes significant latency. You can
> always scale VMWare hosts but there is a cost involved - the higher
> you scale to deal with infrequent utilisation, the less of an
> advantage you gain by virtualising (not to mention licensing costs on
> top).
>
>
> Nathan
>
> On Fri, Mar 6, 2009 at 1:34 PM, Skeeve Stevens <skeeve at eintellego.net>
> wrote:
> > The ONLY solid way that I know to do good server redundancy is with
> Virtual Platforms that support SAN, Fibre Channel/iSCSI with diverse
> heads.
> >
> > We manage multiple instances of VMware ESX/ESXi that have 2+ heads
> backed into SAN's with both heads fed into Cisco switches - nearly
> always 3560G/3750G-stacked configurations.
> >
> > Those have never gone down, even when upgrading the physical hardware
> - VM's just migrate between heads.
> >
> > Some say VM's aren't appropriate for some applications... I would
> debate that as even in a dedicated VM solution there is not many apps
> that wouldn't happily work with that given dedicated NIC, Storage, CPU
> and RAM access.
> >
> > ...Skeeve
> >
> > --
> > Skeeve Stevens, CEO/Technical Director
> > eintellego Pty Ltd - The Networking Specialists
> > skeeve at eintellego.net / www.eintellego.net
> > Phone: 1300 753 383, Fax: (+612) 8572 9954
> > Cell +61 (0)414 753 383 / skype://skeeve
> > --
> > NOC, NOC, who's there?
> >
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> >> -----Original Message-----
> >> From: ausnog-bounces at lists.ausnog.net [mailto:ausnog-
> >> bounces at lists.ausnog.net] On Behalf Of Michael Bethune
> >> Sent: Friday, 6 March 2009 12:14 PM
> >> To: ausnog at ausnog.net
> >> Subject: [AusNOG] Back of envelope II
> >>
> >> Thanks folks for all the responses.
> >>
> >> Is it possible to do auto fail over redundant switching and what if
> >> anything
> >> in the Cisco range would do it?
> >>
> >> I remember using a dual cisco catalyst, but you ended up with a pair
> of
> >> tails, 1 from each catalyst, with a heart beat connecting the two
> >> catalysts
> >> together. Has the state moved on to allow you to have transparent
> (to
> >> the
> >> connected hosts) redundant switching?
> >>
> >> Michael.
> >>
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