Practical limit to the number of hosts on Apache?
 

Hello all!

One of the clients I do work for hosts about 500 websites across 13 windows servers. He has public IP's for each site. Right now his setup fills an entire rack at a hosting facility. He woiuld like to scale his gear down to a half a rack, so he needs to get down to 6 or fewer machines from 13. I suggested Apache webservers, assuming that they could handle larger loads than IIS on win2000 allows.

I expect that there isn't an absolute limit to the number of hosts on a linux based server, but can anyone suggest a practical limit of how many sites one machine can hold? In the 6 machines, The total load would be like 500 sites, 6 databases, 2 email servers, and 2 DNS servers. I was thinking of putting about 250 sites on each of 2 machines, run 1 database only server, 2 DNS/email servers, and seeing how that behaves.

There would not need to be any virtual hosts, this guys does have 2.5 class C blocks of usable public IP addresses, so that won't need to play a part in your answer. Thanks for your help.

Peace,
JimBass

Hell, I'd just virtual host all 500 of em on one box and sync the server to a mirrored server for load balancing and failover. But what your doing sounds sensible as well, more work but sensible. And the idea of using a dedicated DB server and some redundancy in your DNS is a good idead as well. Sounds like your on the right track. I haven't seen an upward limit on what apache can do with Vhosts but I have seen servers that have over 1000 on one, if your going to have 250-500 vhosts on one box consider using a seperate vhosts file just to keep things organized, otherwise your httpd.conf is gonna get REALLY long and confusing.

Good luck,
linux_terror

I'll second the above post about having a seperate vhosts file.

Really the number of servers a box can successfully serve is variable. For instance if 499 of the sites only do a couple of thousand hits a month but another does 100,000 a day you might want to set it up having 499 on one box and the other on a box by its self.

I would take a look at the average traffic each of the 500 sites takes in a month, week, day and decide on the server layout in that manner.

Also, it depends on the hardware your running the server on. A dual Opteron or Athalon 64 with 2GB of memory can deal with a hell of a lot more load than a p4 2.5Ghz with 1GB of ram.

As you can see this is a fairly complex question. I would google "apache performance tuning" or something similar and compare your specs and traffic with what others have and go from there.

Thanks for the input. None of the sites are actually "busy", so I'll probably split them by traffic onto the 2 machines. One of the new machines is being delivered to the client on Monday, and it will be a dual processor of some sort with 2 Gb of RAM, so it is on the higher performance end of things. I'm very glad to know someone has seen over 1000 sites work on a single machine!

Also I many be misunderstanding something - I thought virtual hosts only came into play when you wanted multiple sites to show up under 1 IP address. Each of the sites have their own IP under his current setup, and I thought it would be fine to continue that.

Another reason to keep it is simply that the DNS servers (even though they are windows) are running BIND 9.2, so I can just wholesale import the named.conf and all the files, only change the line in the named.conf that reads "c:/bind/named" to "/var/bind/named/" or whatever the path to the files should be.

I know nothing about the database side of things in either win or linux, so I'm going to leave that to the folks that do that work. All I have to do is configure the systems and get them operational.

Thanks,
JimBass