It turns out this is because of my htaccess file.

In my htaccess I had the following lines to stop anyone accessing my WordPress Admin if they were outside of my IP address:

<LIMIT GET>
Order deny,allow
Deny from all
Allow 100.8.8.8
</LIMIT>

This stops anyone assessing myWordPress admin unless they are logging in from my IP address. Apparently this is now updated and to do this you now use the following command:

<LIMIT GET>
Require IP 100.8.8.8
</LIMIT>

I changed this and no more server 500 error!

I’ve just typed this up in case anyone else has the same problem. My new htaccess file sitting in my wordpress/wp-admin folder looks like this:

AuthUserFile /dev/null
 AuthGroupFile /dev/null
 AuthName "Example Access Control"
 AuthType Basic
 Require ip 220.233.28.8 

My http://macintoshhowto.com site is getting 150K visits a month, http://dubbo.org gets 20K visits monthly and http://mac-host.com/support gets 60K, plus I host http://dpc.org.au and http://wpcc.org.au and a few other sites on the same server!

Currently I’m using bluehost.com and it costs me 6.95 per month – pretty cheap and very reliable, it’s just struggling with so many hits.

I have been looking into an alternate server. I want a really good quality server with no downtime for my macintoshhowto.com site. After some research I came up with the following as my top two options:

http://www.layeredtech.com
I could get a VPS server here with 2 gig of ram, 20% CPU usage, 60 gig hard drive and cpanel access for about $115 per month. I think they are used by ma.tt and WordPress.com. Their technical support was very helpful and they seem very reliable. It would come all setup with c-panel ready to go.

http://www.rackspace.com/
I could get a cloud server for about $100 pm but I’d have to install all the server and-panel software on it from scratch. I could get a cloud site which would come installed but now we’re looking at about $150pm. cloud sites looks like the best option, it can deal with 2 million page views per month.

Media Temple and iWeb were my other options.

Note the huge jump from $7 a month at bluehost! It seems that when you go from shared hosting to VPS it’s a huge jump.

So I decided to go a different direction. I split my bluehost sites up and moved macintoshhowto.com to it’s own server.

Bluehost had a reseller option for $20 but the total bandwidth was limited to the same as one account. They also have a pro option for $20 but it has no more CPU power. So it seems like multiple accounts is best back for the dollar.

To do this I used websitemovers.com and they did a good job.

How to split a domain off your account:
1. setup new account with dummy domain name.
2. move files across (websitemovers did this)
3. change local hosts file so you can test new site ‘live’
4. manually unnasign domain name from origin c-panel
5. manually add the domain (parked) to new domain
6. ask bluehost to make new parked domain the primary one
7. wait 5 hours, but I only had to wait 3 and it was working.

Maybe I could have done it myself, but I’m happy to pay someone else as I don’t want this to take up any of my time.

If I want to do it again in the future I probably follow these instructions from media temple for the move across bit:
http://kb.mediatemple.net/questions/1892/Migrate+to+a+%28dv%29+from+a+%28gs%29

Lower the TTL on the DNS. (not necessary??)
auto mysql backup to a folder like cpbackup/daily/domain/mysql/domain.sql and .create
maybe here search for old pathnames.
Then upload the SQL.
Backup from c-panel (to file like backup-mon-jan-etc zip file 140Mb – the file directory)
maybe unzip and check for pathnames in php files??????????
then upload the zip and unpack files
test
change DNS entries.
lower TTL again.

I’ve upgraded to a dedicated IP with the new blue host account.

So far NO CPU throttling at all!

Here’s a good little site to work out how many other people are sharing your IP address on a server:
http://www.yougetsignal.com/tools/web-sites-on-web-server/