On NT, 300,000 TCP connections that are idle means that 300,000 socket handles are open. On *nix, it means that 300,000 processes are running. This is a big deal.
There's more to large systems engineering than network bandwidth. Larry Osterman -----Original Message----- From: Arnt Gulbrandsen [mailto:[EMAIL PROTECTED] Sent: Wednesday, December 17, 2003 11:48 AM To: Larry Osterman Cc: Christof Drescher; IMAP protocol mailing list; DINH Viet Hoa Subject: Re: Extension for status updates of non-selected mailboxes? Larry Osterman writes: > TCP connections are NOT cheap, and do not scale infinitely. When you > have 30,000 clients connected to your IMAP server (a very reasonable > number for a large farm), and each of them is opening 10 mailboxes, > you're talking 300,000 sockets in use. > > That will tax the limits of ANY operating system. I'm not saying the total cost of IMAP clients is low, merely that the cost of idle TCP connections is. (Note: Idle.) 300,000 TCP connections with an average of four packets per hour is not a very difficult task, if that's all there is. Now, if you talk about watching 300,000 mailboxes on behalf of 30,000 users using one piece of hardware, that's a much more challenging job. --Arnt
