Re: Redundent Debian linux web server

Thanks for the comments Jeff. I should explain a touch more why I was looking
to "overkill" my clients setup. He often gets hit by / . which is good for
business... when the server stays up and alive... :)

Chris

Quoting Jeff Fisher <guppy@techmonkeys.org>:

> chris@fazekas.net wrote:
>> Dick,
>>
>> I gather you could do a round robin DNS as suggested. You could also
>> look at
>> doing a heartbeat server style server setup. Although, you'll probably
>> still
>> have to do some sort replication of your DB to keep things current. The
>> problem I ran into is, if the Primary server is replicating to the
>> secondary
>> server, does the Secondary server replicate back to the Primary server?
>> And,
>> what happens if data is written to the DB on the Primary and Secondary
>> at the
>> same time? I'm not sure if MySQL replication can handle that.. if someone
>> knows exactly how that would work, please do tell.
>
> MySQL replication is normally done just master -> many slaves; however,
> if you handle things like auto increments in your code, you can do
> master/master without too much issue -- or you can use MySQL Cluster.
>
> If you want to have a failover for your master MySQL server, I would
> recommend using DRBD and mirror /var/lib/mysql using it to the other
> machine -- then if the primary fails, you can become the primary and
> start serving up data.
>
>>
>> The scenario I had looked at for my client was setting up 1 file server, 1
>> database server, and 3 or 4 single hard drive machines running apache web
>> server. (total 5-6 servers, the first 2 in RAID5/6 configuration, the
>> 3-4 in
>> RAID0). I was then thinking about using a load-balance appliance, or round
>> robin DNS. My clients site is running about 30,000+ unique sessions per
>> day,
>> the entire site is MySQL and ColdFusion MX 7.
>
> I highly recommend LVS (Linux Virtual Server) for doing load-balancing,
> we use it on a fairly busy mail server.
>
>> My client opted out on that due to the cost, so we ended up going with
>> an hourly
>> rsync, and MySQL replication. The second server just acting as a
>> fail-over only
>> (not really a load balance solution, more of a primary and secondary.
>
> That many machines seems like overkill for 30,000 sessions per day. One
> standby machine would make sense IMHO.
>
>>
>> If a problem happens on the primary, I have a script (monitoring the
>> site from
>> the Secondary) that re-writes the DNS files and restarts Bind
>> "auto-failing" to
>> the secondary server (with a 30 second TTL).
>
> I recommend keepalived for this rather than relying on DNS. Just move
> the IP to whichever box is the primary at that moment in time.
>
> Jeff
>
>
> --
> "Well, there's SPAM, egg, sausage, and SPAM. That's not got MUCH
> SPAM in it."
>
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Received on Wed Jul 26 23:55:33 2006