That can be addressed with DNS round robin. The only issue is how the
user's OS responds to no response from one IP address. Check out how
irc.freenode.com does i
On Wed, May 19, 2010 at 9:09 PM, Ed Knapp <
catbertek@hotmail.com> wrote:
> One thing struck me here with your description...
>
> “and a change to the DNS and we are off and running”
>
> While your DNS records might be changed relatively quickly during an
> incident, the change
> Itself can take quite a while to trickle down to the end users/clients out
> in the cloud.
> Any client’s DNS resolution that has not expired in the cache nor manually
> refreshed will
> still fail to properly resolve/connect. It doesn’t usually, but I tell
> clients to plan for 48 hours
> Estimated time for the change to completely propagate.
>
> I would hate for you to get blindsided with a person hovering over you
> asking how much longer
> It is going to take before the site is back up and operational. It is
> frustrating when you have
> Fixed the issue [ problem :-) ] but have to just sit and wait for it to
> complete.
>
> There are certainly strategies to mitigate this risk and I do not know if
> you maintain your
> Own DNS servers or do you work through a hosting provider/domain registrar.
>
> I hope this helps a bit.
>
> Ed
>
>
> On 5/19/10 2:07 PM, "keith smith" <klsmith2020@yahoo.com> wrote:
>
>
>
> Currently we have two servers in our main data center. One serves our
> shopping cart. The other contains quite a bit of content that is data
> driven (reads). The content site is very active. The orders on the
> shopping cart are spread apart by one or two minutes during the busiest part
> of the day. We store a lot of data with each order so most of this is
> writing. The shopping cart is backed up to the server in the other data
> center. Supposedly if there is a problem, a few things need to be done to
> the backup server in preparation to make it live, and a change to the DNS
> and we are off and running.
>
> The problem I am trying to solve is the other server (content site) is not
> currently backed up automatically.
>
> Another layer of this is these are managed servers. We have an excellent
> relationship with the data center owner and have 24/7 access to him and his
> staff. He manages all three servers and has always done a good job.
>
> I am the one tasked with keeping our sites online 24/7.
>
> I was hoping by configuring two servers, each in a different location, that,
> in the event of one of the data centers being completely severed from the
> Internet that the other server would automatically, without any human
> intervention, take over the full load of the other server and those visiting
> either of our sites would not know there had been an issue.
>
> In a nutshell I am trying to create an automated backup that is a automated
> fail over solution.
>
> I appreciate all your feedback!
>
> ------------------------
> Keith Smith
>
> --- On Wed, 5/19/10, Dan Dubovik <dandubo@gmail.com> wrote:
>
> From: Dan Dubovik <dandubo@gmail.com>
> Subject: Re: load balanced configuration
> To: "Main PLUG discussion list" <plug-discuss@lists.plug.phoenix.az.us>
> Date: Wednesday, May 19, 2010, 1:45 PM
>
> The question I have, are you trying to actually load balance things? Or just
> have a remote location that you can fire up with live data at a moments
> notice? Basically, are you wanting an active/active configuration, or
> active/passive?
> active/active across DC's can get kind of hairy depending on what the
> network looks like. active/passive won't give you any performance gains,
> but can simplify the configuration, while providing the HA you seem to be
> after. As Kaia pointed out, what the traffic looks like (reads vs writes)
> is a consideration. If it is something that users don't write to, and data
> doesn't have to be replicated across DCs frequently, this further simplifies
> things.
>
> Ultimately, the configuration will depend on what the application and
> network looks like currently, and what level of redundancy you want / need.
>
> -- Dan.
>
> On Wed, May 19, 2010 at 1:40 PM, Matt Iavarone <matt.iavarone@gmail.com
> </mc/compose?to=matt.iavarone@gmail.com> > wrote:
>
> I think the original question was around stateless load balancing, not
> clustering. Cross DC clustering is a headache, but HA web sites aren't
> exactly terchnical challenges these days.
>
> On May 19, 2010 4:33 PM, "Alex Dean" <alex@crackpot.org
> </mc/compose?to=alex@crackpot.org> > wrote:
>
>
> On May 19, 2010, at 2:47 PM, keith smith wrote:
>
>>
>>
>> Hi Plug,
>>
>> I am considering combining the ... You're entering a world of pain. :)
>
> HA is cool, but is no panacea. If you haven't actually experienced downtime
> due to your server crashing or your datacenter losing connectivity, I
> recommend thinking long and hard about it. Don't solve a problem you don't
> have. The downtime created from unneeded failovers will likely exceed the
> actual/real downtime caused by either a server or datacenter being offline.
> Managing the cluster itself (as distinct from the services provided by the
> cluster) needs to be accounted for as an expense/responsibility.
>
> I don't want to sound overly pessimistic. I've set up quite a few HA
> clusters, and actually enjoy it most of the time. But it WILL cause you
> headaches in the middle of the night which you wouldn't have had if you only
> had a single server.
>
> Leave yourself lots of time to set up a development/test cluster, and abuse
> it in many ways. Pull out network cables, kill the switch, yank out power
> cables, etc. Do this with real hardware, not VMs.
>
> When the cluster nodes lose contact with each other, both will decide to
> become primary. This is a split brain. This can happen when the switch
> in-between them gets busy and starts dropping pings. Now, you can always
> recover from such things. I'm just recommending you become very familiar
> with these issues before going live with this setup.
>
> http://clusterlabs.org/wiki/Main_Page
> http://people.linbit.com/~florian/heartbeat-users-guide/
> <http://people.linbit.com/%7Eflorian/heartbeat-users-guide/>
>
> Let me/us know if you have specific questions once you start setting things
> up. Good luck!
>
> alex
> ---------------------------------------------------
> PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us
> </mc/compose?to=PLUG-discuss@lists.plug.phoenix.az.us>
> To subscribe, unsubscribe, or to change your mail settings:
> http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
>
> ---------------------------------------------------
> PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us
> </mc/compose?to=PLUG-discuss@lists.plug.phoenix.az.us>
> To subscribe, unsubscribe, or to change your mail settings:
> http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
>
>
> -----Inline Attachment Follows-----
>
> ---------------------------------------------------
> PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us
> </mc/compose?to=PLUG-discuss@lists.plug.phoenix.az.us>
> To subscribe, unsubscribe, or to change your mail settings:
> http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
>
>
> ________________________________
> ---------------------------------------------------
> PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us
> To subscribe, unsubscribe, or to change your mail settings:
> http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
>
> ---------------------------------------------------
> PLUG-discuss mailing list - PLUG-discuss@lists.plug.phoenix.az.us
> To subscribe, unsubscribe, or to change your mail settings:
> http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
>
---------------------------------------------------
PLUG-discuss mailing list -
PLUG-discuss@lists.plug.phoenix.az.us
To subscribe, unsubscribe, or to change your mail settings:
http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss