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My sys-admin colleagues have an Exchange 2003 R2 SP2 server running Outlook Web Access (OWA) through an IIS 6 server (naturally).

OWA seems to crash every couple of weeks. Looking at the Application Pool recycling in IIS, I notice that all of the Recycling options (by time, by number of requests, fixed time etc) are switched off.

Would it be a good idea to switch on Application Pool Recycling (e.g. at 3am every day or something like that) or is recycling the Application Pool not recommended for OWA?

edit: Inconclusive answers so far ... Has anyone else tried this?

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ExchangeApplicationPool shouldn't be recycled, if it is configured to then OWA can become unreliable.

In a default install of Exchange 2003 on Windows 2003 it looks like this:

Recycling Tab

  • Everything Unchecked

Performance Tab

  • Shutdown worker processes after being idele for (unchecked)
  • Limit the kernel request queue (checked - 1000 Requests)
  • Enable CPU Monitoring (unchecked)
  • Maximum number of worked processes (1)

Health Tab

  • Enable pinging (Checked 30 seconds)
  • Enable rapid-fail protection (Checked)
    • Failures (5)
    • Time Period (5)
  • Startup time limit (90)
  • Shutdown time limit (90)

Identity Tab

  • Varies depending on options

KB906907 : Instructions on re-creating the ExchangeApplicationPool

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Are you sure the app pool shouldn't be recycled? Why cant OWA handle it? I ask because someone else gave the opposite answer... – codeulike Dec 14 '09 at 17:30
I resolved an intermittently unavailable OWA instance by restoring the AppPool to the default settings, the only thing changed was the previous Sys. Admin. had configured the AppPool to recycle its worker threads. Potentially the act of editing the AppPool may have restored a corrupt IIS metabase, however I found several resources online that suggested resetting the AppPool and it worked for me. – Richard Slater Dec 14 '09 at 18:20
The key is making sure it recycles at a reasonable time. It becomes unavailable during the recycle. – Dave Holland Dec 14 '09 at 19:29
I really wish that I could remember the details; searching around I have found a couple of instances of the ExchangeApplicationPool not restarting due to Event ID 1013 (A process serving application pool 'ExchangeApplicationPool' exceeded time limits during shut down). – Richard Slater Dec 14 '09 at 20:04

There should be no harm in recycling your OWA application pools. Choose a time when your users won't reasonably be on it and do it then.

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Have you tried this yourself? The other answer says I shouldn't do this ... – codeulike Dec 14 '09 at 17:30
Admittedly not with 2003, only with 2000. I had my pool for OWA in 2000 resetting every 48 hours, without issue for 4 years. – Dave Holland Dec 14 '09 at 19:28

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