webhosting - 1650's versus 6650's etc.

Jerker Nyberg jerker at update.uu.se
Wed Jun 19 12:08:00 CDT 2002


Hello,

I got a question about how we handle failover between our Internet
connections, and I hope that it is ok that I send an answer directly to
the mailinglist.

We don't have failover today. We try to use a low TTL and update our DNS
for the important services if one of the connections fail.

We will in a few weeks change Internet Service Provider and then we will
be connected to different redundant routers in their network. We can move
our IP-addresses with us because we are our own Local Internet Registry.

However, I have thought of another way to do "poor mans high-availability
hosting". Let the zones be handled by nameservers located at your Internet
connections, at least one on each. Let the nameservers have different
information for each zone saying that the web/pop/imap/etc-servers are
located on the same Internet connection as it self. Use a very low TTL.
When one of the connections fail, only the nameserver located on the other
Internet connection will answer. And that nameserver will say that the
web/pop/imap/etc-servers are located on the same Internet connection as
itself. Everything will hopefully work, without any dynamic updates to DNS
and also when different parts of the Internet have different types of
routing failures. But don't use this without asking any DNS-guru how many
rules it break and if it's a generally bad thing to do, and if you do,
please tell me, I'd like to know.

And keeping to the topic of this mailinglist, only try this with Dell
Poweredge servers running Linux. :-)

Regards,
Jerker Nyberg.
Uppsala Sweden.


On Wed, 19 Jun 2002, Jerker Nyberg wrote:

> 
> Hello Bryce,
> 
> Check out LinuxVirtualServer and High Availability for Linux at
> http://www.linuxvirtualserver.org and http://www.linux-ha.org.
> 
> I use a combination of Heartbeat/Ldirector/LinuxVirtualServer for load
> balancing with the current setup - see below. It is as you can see not
> redundant everywhere, but at least the webservers are. Not NFS or MySQL or
> switches.
> 
> As LVS-servers I use Dell Poweredge 2300. As webservers I use Dell
> Poweredge 2x2450/1x1550/3x1650/1xNoname. As databaseservers I use Dell
> Poweredge 2300/2550 and as NFS-servers I use Dell 4300/2500.
> 
> The servers handle hosting for around 3000 domains and in our case the
> current limiting factor is CPU om the webservers (lots of CGI-scripts and
> other strange things are run) and CPU on the databases (customers doesn't
> always use indexes..) and the outgoing traffic is maxing 8 Mbit/s.
> 
> My impression is that the biggers servers does not have a as good
> price/performance (for trivially parallel applications as webhosting) as
> the smaller servers. For a databases and similiar applications the bigger
> servers can sometimes be good though.
> 
> Take care.
> 
> Regards,
> Jerker Nyberg.
> Uppsala Sweden.
> 
>              ............
>              :          :
>              : Internet :
>              :..........:
>               |        |
>             Tele2    UUNET
>               |        | 
>           +------+  +------+
>           |router|  |router|
>           +------+  +------+
>               |        |       +---------+
>             ====switch====-----|smtp2/ns2|
>                |      |        +---------+
>              +---+  +---+
>              |LVS|==|LVS|
>              +---+  +---+
>                |      |
>    =============switch=====================
>     | | | | | |        | |    | |        |
>    +------------+     +---+  +---+  +----------+
>    |mail/web/ftp|+    |NFS|+ |SQL|+ |ssh/telnet|
>    +------------+|+   +---+| +---+| +----------+
>     +------------+|+   +---+  +---+
>      +------------+|+
>       +------------+|+
>        +------------+|
>         +------------+
> 
> 
> On Tue, 18 Jun 2002, Bryce C wrote:
> 
> > Hi,
> > 
> > A bit of random thoughts that I'd like to hear others
> > comments/experience on... 
> > 
> > We currently use mainly 1650's for webserving
> > (apache/php/mysql/etc.). I'm curious if anyone is
> > using some of the "bigger" Dell servers (6650's) for
> > the same type of use?
> > 
> > Any thoughts on scalability, etc.?
> > 
> > We've always had the philosophy of keeping a modest
> > number of clients on each 1650 so that in the worst
> > case an outage would only effect those customers. 
> > 
> > However it seems to me that if things are set up
> > correctly (RAID, redudant power supplies, etc.) that
> > an outage shouldn't be too much of an issue.
> > 
> > Given enough RAM and CPU (say 4 gigs and 4 Xeon's on a
> > 6650 versus 1 gig and 2 PIII's on a 1650) what would
> > you do if given the choice?
> > 
> > Of course I think the bottom line is that I'm just
> > trying to find an excuse to justify putting in an
> > order for a nice 4 proc 6650 :)
> > 
> > Anyway, I'd be interested to hear everyones thoughts
> > and comments on the matter. I'm always a bit nervous
> > to try to place too many clients on a single server
> > but it seems like the some of the bigger webhosts/ISPs
> > etc. must be doing things like this (ie. tons of
> > people on more powerfull servers).
> > 
> > 
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! - Official partner of 2002 FIFA World Cup
> > http://fifaworldcup.yahoo.com
> > 
> > _______________________________________________
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> > 
> 
> 
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