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I am setting up a new Win2008 web server with IIS7 for the first time - I have been taking my time learning as I go.

So I am wondering if you would you create a separate application pool for each site you add? I have an old win2003 server with all the sites in the default app pool and it runs great, but was told I should split them up??

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I recommend it, and I personally create separate app pools for most everything.

Separate app pools give isolation in case one site breaks the app pool it doesn't hurt the others. You can also secure it with each in their own app pool. There's a bit of extra RAM overhead for each app pool, somewhere around 50MB for the latest .NET framework version. It's also easier to troubleshoot when each are in their own app pool.

Just make sure if that if you monitor your sites that you monitor all of them because if one fails, the others will usually continue to work, making the monitor only useful for the site it monitors.

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Thanks Scott - Is that an extra 50mb per app pool for .NET sites?? As that's what I run and the server only has 2GB. I use Umbraco so was thinking about having an Umbraco app pool for the Umbraco sites, and then a seperate app pool for all the custom sites so I don't run out of memory – leen3o Dec 5 '09 at 17:24
Hi Lenn3o. I stand corrected. I just checked a new app pool running the latest hotfixes and made sure to load an page and it's only using 16MB to start. That's about the extra memory that you'll have for each app pool, which really isn't that much. If you have many dozens of sites, then yes, consolidating them is important if you only have 2GB of RAM. If you have a dozen or less then there are the advantages mentioned above to providing them with their own app pool. – Scott Forsyth - MVP Dec 6 '09 at 3:18

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