----- Original Message ----- From: "Brian Baquiran" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Saturday, January 12, 2002 3:33 AM Subject: Re: [plug] clustering...
> From my experience, your network (specifically, your incoming pipe) will > get saturated WAY before disk I/O becomes a problem. Why? Because each > of your users has X number of friends, enemies, aquaintances, and > spammers trying to send him mail. Since the time required to handle an > SMTP session will, in most cases, be more than the time required to > queue and deliver the message locally, this is only true if there is a huge simulteneously connections of smtp or even a single smtp connection (eg. email attaching a huge file) that eats up your whole bandwidth .... but the heavy load is not end up there because once the mails are transfered to your server by simultenously or single smtp connection, imagine the reading, checking and rewriting of incomplete headers, checking and filtering email's bodies and headers for spamming and viruses (if you have one), one sender to multiple recipients (with or without attachment - read i/o operations), moving from temporary location to spool or queue directory after the mail is clean and complete, etc that makes your disk i/o busy. > your main limiting factors for > performance (mail thoughput) will be your network latency and bandwidth. this can be easily solve by two ways: 1. rate limit or apply QoS to your bandwidth 2. configure your TCP send and recieve WINDOW size email service speed and throughput is not almost visible to humans compare to www or proxy service and others. so therefore its ok to shape your smtp bandwidth and give bandwidth to other priority services. > > > (blocking reads or > > blocking writes which causes pendings and delays) > > You are much more likely to encounter blocking reads/writes on the > network than on disk. yup thats true but what im saying here is that, when your disk i/o gets busy, disk reads and writes starts to block which causes delays and pendings of transactions on a heavy loaded email server. fooler. _ Philippine Linux Users Group. Web site and archives at http://plug.linux.org.ph To leave: send "unsubscribe" in the body to [EMAIL PROTECTED] To subscribe to the Linux Newbies' List: send "subscribe" in the body to [EMAIL PROTECTED]
