How many sites are too many

[andrewsmd]

This is probably a horrible question, but I don't really know what to ask. Here's what I'm looking at. We have around 180 sites on a Win 2k8 r2 server. 8 G RAM, with an INTEL Xeon e5520 2.27 GHz processor. What I'm wondering is, how many websites are too many before I should get a second server? I know there are a ton of factors that would play in, such as traffic, size of the sites, etc. I guess what I'm asking is either, does someone know a general answer, or how do I go about deciding if I should keep adding sites to this server, or get another one? Thanks,

[dstiles]

I would say that bandwidth is the main criterion.

A few years ago I had perhaps 40 sites on one server, mostly small sites. One site got so much traffic it pulled the server down (lots of 500 errors in the stats). Moved that site to its own server and everything was fine again.

Find out what your hosting company allows you then agregate the sites' traffic; add a bit for peaking and see how close they match.

[andrewsmd]

We host our own servers in a data center. We have no limit on bandwidth. I can see our bandwidth usage from a stats program we have. I guess my question would be, how much is too much then?

[robzilla]

Do you keep track of load averages and memory usage over time, as well as other signals that are relevant to the health of your server (disk space, network throughput, concurrent connections, etc) at any given time? That's what I'd be looking at, with special attention to the (un)availability of room for growth and the occasional spikes in traffic. "Too much" is when you're approaching a bottleneck in any of those areas.

Even then, you don't necessarily need another server, unless you'd like to spread the risk of downtime. A good look at optimizing your most demanding sites might suffice in improving the overall health of the server.

[andrewsmd]

Well, most of our sites that generate a lot of traffic are dotnetnuke sites, so there's really no way for me to optimize them. As far as disk space expansion, this server is virtulaized on a beast of a machine, so I can add more disk space if I need to. As far as traffic, we have smarter stats installed so I can pull just about any kind of report on bandwidth I need to. What do you think I should look at specifically? I can see a total for one week in bandwidth is around 35.5 G. I'm never hitting above 3G an any single hour though. I guess I've just noticed something of a slow down on some of my sites. Is it better to have a more powerful server, or to have two? As far as an availability standpoint, since this is virtualized and backed up every night, I'm not opposed to having just one server. I just don't know which route is better, one big server or two smaller servers.

[robzilla]

I'd say one big server is easier to manage than two smaller ones. How do the memory and CPU stats look, though? Are they healthy, with some room for growth?

[Marshall]

Is it better to have a more powerful server, or to have two?

I don't maintain my own servers, but I would think spreading the risk of problems over two servers is better than running the risk of say losing everything if one goes down. Just an opinion.

[andrewsmd]

Well see, that's the point of virtualization. Should something go wrong, we have another backup server that instantly comes up and has all of the changes from the first server pushed over. Now, if something were to happen to my actual web server, then yes everything would go down. But I can pull backups from any day and attach the vhd file and have the server back up in a matter of minutes. So from a risk factor, I see two servers as doubling my chances for something to go wrong. Not to mention, doubling the times I have to install updates and things. However, if it's better to go with two small servers instead of one big one, that's the way I'll go. Can any experienced hosting administrators out there offer me some advice?

[dstiles]

You mention unlimited bandwidth but there is a practical limit in the network connection between your server and the data centre's big pipe. On mine this is 100Mbps.