Date: Mon, 23 Oct 2006 15:00:16 -0500 From: Damian Wiest <dwiest@vailsys.com> To: freebsd-questions@freebsd.org Subject: Re: Small Redundant web/mail setup Message-ID: <20061023200016.GB5392@dfwdamian.vail> In-Reply-To: <004001c6f34b$c9640570$3c01a8c0@coolf89ea26645> References: <7.0.1.0.2.20061018082011.066e8b60@msdi.ca> <004001c6f34b$c9640570$3c01a8c0@coolf89ea26645>
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On Wed, Oct 18, 2006 at 11:57:04PM -0700, Ted Mittelstaedt wrote: > > ----- Original Message ----- > From: "Ian Lord" <mailing-lists@msdi.ca> > To: <freebsd-questions@freebsd.org> > Sent: Wednesday, October 18, 2006 5:34 AM > Subject: Small Redundant web/mail setup > > > > Hi, > > > > I need to setup a high-availability setup for mail/web setup > > > > I was thinking about the following setup: > > > > 4 servers total: > > > > overkill, just asking for trouble. > > > Data Servers: > > 1 Server holding all the websites data and mail messages. It > > would serve these files via nfs to the application servers. > > It would also run mysql > > > > A second server Also sharing it's content via nfs, > > replicating it's data though rsync each ?? minutes. The mysql would > > run as a slave of the primary > > > > Application Servers: > > Both servers would be running apache, php, sendmail and > > posfix and would serve content from the share nfs drive. > > > > 1- Is this a viable solution, I mean by that, Is it Like this big ISP > > are set up ? > > > > no > > The really big ISP's use proprietary commercial clustering solutions > that make multiple systems appear as one single system. We are talking > hundreds of thousands to millions of users. We are not talking 5000 > users or fewer. > > You can easily serve 5K users on a single server. You just need to > get good hardware. In other words, costs start at $5000 and go up. > > A lot of people are under the misconception that they can get several > cheap $900 servers and assemble them into a redundant setup that is > highly reliable. > > The real secret is in getting expensive name-brand hardware that > doesen't go down. If you can afford that, your fine. If you can't, > then you need to find a different table to play at. > > Ted Isn't part of the point in running a redundent configuration that you can buy cheap(er) hardware? A $600 machine should be powerful enough to handle that many users. Just make sure you are using RAID 1+0 filesystems, keep replacement parts on hand and are performing regular backups. The real question to ask is what is the provider's SLA and how much does an hour of downtime cost the provider. In my experience, the only things to die on servers have been fans, disks (really the motors), and the occasional power supply. The only things a more expensive system may give you are additional power supplies, hot-swap drive bays and multiple CPUs. Other than the system board and possibly the processors, the server's components come from the same sources as your commodity hardware. I think the setup described above is viable, though I would consider running the database (with master-slave replication) and application services on the same server assuming it can handle the load. Also, you can probably get away with using something like rsync to push changes to your WWW servers. I'm not sure about email, but you could NFS export your mail directories from a central server to the two application servers. Just be aware of NFS' failure modes. So, I'd go with two, user-facing systems and an administrative system that receives email and possibly hosts your code repository. If you can afford it, get systems with redundent power supplies and hot-swap drive bays. Depending on your userbase, you may want to consider a robotic tape library so you don't have to manually change tapes. I've heard some talk of people using raw disks for backups, but I don't have any experience with that type of setup. -Damian
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