sessions or not to session

[Anon]

Hello!

Is php's new session management efficient enough to store every user that logs into my community site a session variable with that userId?
If I am planning for a few hundred people to be logged in at once.

The problem is say the session times out after 20 minutes, if a user leaves after 5 minutes that session will still be alive. SO even if 100 people are logged in, the server may have 150 sessions in memory (some sessions are yet to timeout).
any suggestions on how most other community sites might be dealing with this?

[yelvington]

Nat, they're not stored in memory. They're stored on disk. No problem. Sessions are ideal for what you describe.

[Anon]

sessions are stored on disk?

in ASP there in memory correct? (i'm prog mostly in ASP)

[sekundek]

You can check your /tmp dir and you'll see.
Sessions are very very good.

[Anon]

what do you mean?
is there a article that details the inner workings of php4 sessions?