Re: [SLUG] Clustering

From: Steve (steve@szmidt.org)
Date: Fri Jun 11 2004 - 15:27:43 EDT


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Friday 11 June 2004 02:30 pm, dhenao@tampabay.rr.com wrote:
> Steve,
>
> First of all, thanks for answering my email. Basically, this is a job that
> I am going to do for a friend. He has a small business (dsl connections+web
> hosting). Basically eah server has 2 nic cards. Therefore, I was thinking
> about having them connected with a crossed cable or to a hub to update the
> backup server everytime there is a change in the main server (considering
> the fact that they are in the same location). They have one Bright House
> connection and one Verizon connection. The last one is supposed to be
> better than a normal DSL. Finally, what I want to accomplish is simple. If
> for any reason any of the servers goes down either because the ISP or a
> hardware failure, the other server will jump up, and there won't be any
> down time.

OK, you could put an external connection to each computer. Then run a script
that monitors the cable connection (as it's the faster of the two).

Then if you cannot get to your next router upline you switch to the DSL
connection. Keep monitoring cable for coming back up and return as it does.

Of course you said web hosting. This poses a different problem since it wont
be found without updating DNS. The normal way of acheiving High Availability
(HA) is to have a system in front of your web servers and when the primary
goes down switch to secondary. Except you want to do it the other way around.

This would also require a DNS server in your control if you want to go this
way. Both needs access you will not easily get.

The final solution (while keeping things real) is to install two OpenBSD web
servers. OBSD has a new feature with V3.5 which allows a computer to assume
the identity of another if it goes down. You establish a serial connection
(or network) between the two and that connection will let the secondary
monitor the primary and take over if needed.

Now OpenBSD is easy to install and configure. Install only takes 15 minutes.
Configuration will take longer of course. But it has HA services built in so
thats for free. Plus it's the best O/S in the world when it comes to
security. (Makes Linux look like a toy.)

If you read up on the man pages and search the archive before posing questions
on the 'misc' mailing list you will get competent help. There's even a
beginner list someplace. (google for that.)

Your two needs, HA and backup network connection works against each other so
it's not as straight forward as some things are.

Any other solution I can think of will require high complexity (and know how)
and more computers, including access to services your ISP (Brighthouse) will
not give. Now someone may have made HA work well under Linux but I've not
seen anything that's for beginners. (Though it was a while since I last
looked.) linux-ha.org would be the place to check.

> Thanks
> Diego
>
> ----- Original Message -----
> From: Steve <steve@szmidt.org>
> Date: Friday, June 11, 2004 1:07 am
> Subject: Re: [SLUG] Clustering
>
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > On Thursday 10 June 2004 12:56 pm, dhenao@tampabay.rr.com wrote:
> > > Hi,
> > >
> > > Long time since I wrote down an email here. How is everybody
> >
> > doing.? I have
> >
> > > a quick question for you. I am not really familiarized with a server
> > > environment, but I would like to get some input on how you will
> >
> > resolve> this issue. I have two cobalt 550. They are redhat
> > systems basically...
> >
> > > They are exactly the same machines (hardware and software. I
> >
> > want to create
> >
> > > a cluster between them, but I am also considering the fact that
> >
> > if my ISP
> >
> > > goes down, no matter if I have a cluster, all my web sites will
> >
> > be down
> >
> > > too. Therefore, I have one connection from Bright House and
> >
> > another from
> >
> > > Verizon. Is there any possible way to have this two servers as a
> >
> > cluster.?> I did some research on LVS, but I am still concern
> > about how the DNS tables
> >
> > > will be updated when the first server goes down and the second
> >
> > comes up
> >
> > > with a different ip.
> >
> > Well per my understanding you have two Brighthouse connections at
> > your house.
> > Unless the Verizon one is DSL. They are just reselling Brighthouse
> > network.
> > So if Brighthouse goes down, both of them are down.
> >
> > It's much more efficient to pay say $8 per month for hosting and
> > have more
> > than enough bandwidth (over 50G/mth). This is what I've been doing
> > for the
> > last year. It's more fun to have it in house, but often not very
> > cost
> > effective.
> >
> > If you want to do dns load balancing, hehe, it's going to get a
> > lot worse.
> > The DNS server can do f. ex. roundrobin with traffic but you need
> > to be able
> > to configure it as it does not normally work this way. To have
> > high
> > availability you need to either have a connection that is
> > dedicated between
> > those two so that if the network card goes down you can still
> > notify the
> > other. Or you have another server that monitors them.
> >
> > Now ISP's seldom goes down. Anyone worth his salt have multiple
> > different
> > connections. Your problem is more likely to be a router that gets
> > hit by a
> > surge and or dies for some reason, than you ISP going down.
> >
> > What do you really want to accomplish? What functions/services?
> >
> > > Some questions:
> > >
> > > 1. Both connections and servers are in the same location.
> > > 2. Will dns update the tables knowing that the main server has a
> >
> > different> ip.? 3. Will all the services based on DNS as mail and
> > web be running in
> >
> > > the new machine with the ip numbers incorrectly.? 4. How big
> >
> > ISPs have 0
> >
> > > down.? Do they have different internet providers.?
> > >
> > > Any help will be greatly appreciated.
> > >
> > > DIego
> > >
> > > -----------------------------------------------------------------
> >
> > ------
> >
> > > This list is provided as an unmoderated internet service by
> >
> > Networked> Knowledge Systems (NKS). Views and opinions expressed
> > in messages
> >
> > > posted are those of the author and do not necessarily reflect the
> > > official policy or position of NKS or any of its employees.
> >
> > - --
> > Steve
> >
> > "They that would give up essential liberty for temporary safety
> > deserveneither liberty nor safety."
> > Benjamin Franklin
> >
> > -----BEGIN PGP SIGNATURE-----
> > Version: GnuPG v1.2.4 (GNU/Linux)
> >
> > iD8DBQFAyT4lljK16xgETzkRAiB3AJ9/0KWQZY7UrOR9EpWWdE5WmfIyDwCaAhFK
> > 6ToBbWcixW57Yc0oyJI2TGM=
> > =4uf5
> > -----END PGP SIGNATURE-----
> >
> > -------------------------------------------------------------------
> > ----
> > This list is provided as an unmoderated internet service by Networked
> > Knowledge Systems (NKS). Views and opinions expressed in messages
> > posted are those of the author and do not necessarily reflect the
> > official policy or position of NKS or any of its employees.
>
> -----------------------------------------------------------------------
> This list is provided as an unmoderated internet service by Networked
> Knowledge Systems (NKS). Views and opinions expressed in messages
> posted are those of the author and do not necessarily reflect the
> official policy or position of NKS or any of its employees.

- --
Steve

"They that would give up essential liberty for temporary safety deserve
neither liberty nor safety."
                                Benjamin Franklin

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.4 (GNU/Linux)

iD8DBQFAygezljK16xgETzkRAmzZAKChPRKVtpN9ozJuoIw/2E8BDM3jaACgxSyr
gT5HZQsGMgB/h1nT7tDg14Y=
=l8ZV
-----END PGP SIGNATURE-----

-----------------------------------------------------------------------
This list is provided as an unmoderated internet service by Networked
Knowledge Systems (NKS). Views and opinions expressed in messages
posted are those of the author and do not necessarily reflect the
official policy or position of NKS or any of its employees.



This archive was generated by hypermail 2.1.3 : Fri Aug 01 2014 - 20:26:55 EDT