IMAP on NT at Fermilab

1. IMAP on NTatFermilab Tim Doody HEPNT at CERN December 3, 1998 Doody@fnal.gov

2. Provide users with a central site-wide mail service One site-wide user mail store (black box) with nightly backups GUI and command line client readers available User storage monitoring/management - quotas Standards-based capability to access mail from many platforms (pcs, macs, unix) Easy access to mail from offsite including users foldered mail. Access to e-mail from standard internet browsers Goals of the site Email service at Fermilab Doody@fnal.gov

3. IMAP - Review IMAP stands for Internet Message Access Protocol. It is a method of accessing electronic mail messages that are kept on a mail server. IMAP permits a "client" email program to access remote message stores as if they were local. For example, email stored on an IMAP server can be manipulated from a home computer, an office desktop system, and/or a notebook computer using any IMAP compliant client software. Doody@fnal.gov

4. IMAP - Review The latest version of this protocol is IMAP4rev1; and is on the Internet Engineering Task Force (IETF) standards track - RFC-1730. It has taken almost a decade for this protocol to get noticed by email vendors. Many still having problems with implementing a standard set of client features. More information is available at www.imap.org Doody@fnal.gov

5. IMAP - Advantages over POP... Your stored email is available to you - even when you’re not using your own workstation and same email software package. Doody@fnal.gov

6. IMAP - Implementation • Original Configuration • Software • Windows NTAS • Netscape Mail Server • Hardware • Dual 200MHz Pentium Pro with 192Mb of memory • Server software and mail files located on a 20GB Software RAID 5 disk array • An identical computer system available as hot backup. Doody@fnal.gov

7. IMAP - Related Issues • Online address book • LDAP Server installed for authentication • Server instance created to mirror existing online telephone directory. Available at ldap.fnal.gov. Search base of o=fnal. Sample client configuration online at http://www-dcd.fnal.gov/ldap Doody@fnal.gov

8. IMAP - Fermilab Supported Clients Windows Macintosh Netscape 4.x Outlook Express 4.x Outlook Express 4.x Netscape 4.x Other clients are available. These are supported. See www.imap.org for the most complete list available. Unix Pine Doody@fnal.gov

9. LDAP in Netscape Doody@fnal.gov

10. IMAP - Current Status • Available to all users • Use standard account request form • http://www.fnal.gov/cd/forms/acctreq_form.html • 20 Mb default disk quota • Deleted mail, attachments count against quota • Remember to empty the trash or purge deleted messages • Currently over 600 active users supported on two similar servers -512 MB of memory. (and one hot backup) Doody@fnal.gov

11. Connected users on IMAPserver1 Doody@fnal.gov

12. Fermi custom written software Close to Quota Message Sent To User: Doody@fnal.gov

13. Fermi custom written software Message Sent To User over Quota Doody@fnal.gov

14. Fermi custom written software Quota Exceeded Message Returned To Sender: Doody@fnal.gov

15. 100 Connected Users reached complaints started: Server timed out while getting mail Long time to download new mail Long pauses reading mail Long pauses in foldering mail Performance Issues appeared May ‘98 Doody@fnal.gov

16. Server based - Original Netscape mail software slow, buggy, and support lacking. Software raid is not recommended Fermilab learning curve (We made some mistakes) Using new technologies and/or technologies with no familiarity increase probabilities of failure/problems. Netscape - each message is a file. Netscape\Mailbox\USERX\Folder\subfolder\message Client based - Large mailboxes Constantly mail checking Many reasons: Doody@fnal.gov

17. Read & writes on volume D Doody@fnal.gov

18. September 3rd meltdown A disk failure eventually caused a system meltdown. The long recovery allowed us to reconfigure the system. Mailboxes are now limited to 50 users max and we moved to fault tolerant mirrored sets (separate controllers). Doody@fnal.gov

19. Reads & writes on volume E Doody@fnal.gov

20. Read & writes on volume D Doody@fnal.gov

21. Netscape later releases much better Server timeouts decreased by redefining Master Browser in NT Second NT server added July 98 to help with account load Decision not to continue use of single message store. (maintenance overhead vs. disk $) Issues Addressed - Server Doody@fnal.gov

22. IMAP - Client Tips • Mailbox size • Keep folders that change constantly as small as • New mail check interval • 10 minutes is recommended. Mail can always be checked manually if important message expected possible. With IMAP a change in folder contents causes a list of the messages headers to be sent to the client the next time the folder is accessed. Large folders take longer to update the client. This especially applies to the Inbox. Doody@fnal.gov

23. We are load testing a Dell 6300 - Two 400 MHz Pentium II, 512 MB memory and using hardware raid. Initial tests show improvements, acceptable response maintained with ~ 300 concurrent users with good mix (over 50 users with 10 folders with 1,000 messages in folders and 20 users with 20 folders with 1,500 messages). We are still concerned about heavy disk utilization. Maybe multiple servers (3?), eliminates a single failure point but adds to maintenance. More to come! Where do we go from here? Doody@fnal.gov

24. Issues that need to be addressed • IMAP software (clients) needs to be evolve into more consistent interface/features across software and platforms. (disconnected mode, subfolders, & filtering) • Better management/diagnostic tools for both OS and server software. (nothing new to people using NTAS) • Fermilab PCS needs to get a better understanding of our network infrastructure. (end users with shared and/or switched ethernet segments which can impact perception of server performance). • Netscape sale - good news bad news - We will see? Doody@fnal.gov

25. Questions? Fin - Doody@fnal.gov