Hi, Brian. Thanks for your question.
You can achieve what you want using the following rule:
(The RewriteRule line should not have any line breaks, if Google has inserted any).
This will redirect any requests that end in '.avi', '.pdf', or '.mpeg'
to the matching address on http://secondary.example.com/. If you need
to add more file types, add a bar and the type after '|mpeg'.
secondary.example.com can be replaced with your server's hostname. As
an example, if I wanted to also redirect files ending in '.bla' and
'.pie' to a server 'files.test.com', the line would become:
To answer your questions:
1. This is a fairly good way to serve files of specific types from a
different server, especially if bandwidth is the problem. However, too
many requests for large media files will just move the problem of load
onto the second server. If this is acceptable (for example, if you
wish to ensure your primary web server remains accessable), then this
method should work well.
It is also worth noting that enabling mod_rewrite will slow down
server performance a little, especially if it is applied site-wide.
The effects should be negligible, though.
2. Functionally, it does not matter whether this is included in the
VirtualHost directive, or in a .htaccess file. However, bear in mind
that if it is included in such a way as to apply to every request,
server performance may suffer unnecessarily. A better approach may be
to use it in a .htaccess file only in the directory with media -
'/content/', in your example.
Note that if you did this, you would probably have to change
http://secondary.example.com/$1/$2$3 in the example above to
3. Yes, mod_rewrite is flexable enough to allow this.
To do this, you would need to create a text file containing a list of
possibile servers, for example:
You would then need to add the following directive before the RewriteRule:
RewriteMap servers rnd:/path/to/your/server/list.txt
And finally, modify the rule to something similar to:
This would select one of the servers listed in your text file at
random, effectively spreading the load between them. This isn't the
best solution, since it would not take into account, for example, a
server less able to cope with load than others.
For more information, see:
This isn't really what mod_rewrite was designed for though, so the
performance probably won't be as good as that of a dedicated load
balancer, or software designed to balance loads. A better software
solution may be pound (http://www.apsis.ch/pound/), Pure Load Balancer
(http://plb.sunsite.dk/) or Zeus Load Balancer
(http://www.zeus.com/products/zlb/), as a few examples.
The apache module mod_backhand (http://www.backhand.org/mod_backhand/)
may also be useful if the problem is CPU usage. It does not help with
bandwidth utilisation, though.
I hope this helps. If you have any questions, please do not hesitate
to request a clarification.
The following links may also be of use to you:
Apache URL Rewriting Guide:
Load balancing using mod_rewrite and mod_proxy:
The pound load balancer:
Regular Expressions Reference:
The following searches may also be useful:
'mod_rewrite load balancing':
Clarification of Answer by
14 Feb 2005 16:27 PST
I'll quickly try and explain "^(.*)/([^/]*\.)(avi|pdf|mpeg)$", the
pattern it matches against:
'(.*)' - There can be any characters at the start. Assign them to the variable $1.
'/' - Next, there must then be a '/' character. Don't assign it to a variable.
'([^/]*\.)' - Next, there is a sequence of any characters except the
'/' character, followed by a dot. This corresponds to 'file.' in an
example address http://bla.com/directory/file.avi. It will assign this
'(avi|pdf|mpeg)$' - Lastly, it will match avi OR pdf OR mpeg, and
assign it to $3. The ending '$' character means that the URL must end
It them substitutes the values it matched in place of $1, $2 and $3 in
the second address.
Secondly, the WMV problem. I would agree that it's a content type
problem. I say this because with this kind of redirect, the server
sends a 302 Found HTTP message to the client with the new address. As
far as I know, the client then follows this address, discarding the
headers it received from the first request, so I'm pretty sure it's
not a problem caused by the redirect, especially if both servers
return the same MIME type for the file.
If you request the file directly from the second server and it appears
as plain text, this would confirm it's not a problem with the
redirect. You could try adding
AddType .wmv video/x-ms-wmv binary
in Apache's config file to change the MIME type of .wmv files to
'x-ms-wmv', hopefully forcing FireFox to download it.
Let me know if you have any other questions.