Electronic mail system with methodology providing distributed message store

• US 20020112008A1
• Filed: 12/12/2000
• Published: 08/15/2002
• Est. Priority Date: 02/22/2000
• Status: Active Grant

• Current Assignee: Proofpoint Incorporated
• Original Assignee: Sendmail Incorporated (Proofpoint Incorporated)
• Inventors: Fritchie, Scott Ernest Lystig, Larson, James Stephen, Christenson, Nikolai Paul
• Granted Patent: US 7,117,246 B2
• Time in Patent Office: Days
• US Class Current: 709/206
• CPC Class Codes: H04L 51/23 Reliability checks, e.g. acknowledgments or fault reporting
• CPC Class Codes: H04L 51/42 Mailbox-related aspects, e.g. synchronisation of mailboxes

Abstract

An electronic mail system with a methodology providing distributed message storage and processing is described. In particular, this methodology breaks up how the individual components of message data are stored. Message data itself is broken up into two parts: a metadata (mutable) portion, and an immutable portion. The metadata portion represents that part of the message data that may change over time. This includes message status flags (e.g., the IMAP “message deleted” flag) and the message'"'"'s position within a particular message folder, among other information. The immutable portion, which comprises the bulk of electronic mail data (namely, the message itself), once stored is never edited. Immutable data is written f+1 times on as many unique servers, to tolerate f number of server failures using Lampson'"'"'s stable storage algorithm. The metadata portion is stored 2f+1 times on as many unique servers to tolerate f number of server failures using quorum voting. Once the message has been stored once, instead of being copied, its location is passed around by reference. The system utilizes a two-tier architecture. One tier consists of servers which store message metadata and immutable data, the Data Servers, and servers that operating upon those data, the Access Servers. Message store integrity is maintained in the event of server failure and as the set of Data Servers changes. In the latter case, I/O and storage workloads are dynamically redistributed across Data Servers in an efficient way.

Claims

1. In a electronic mail (e-mail) system, a methodology for storing e-mail messages in a manner to tolerate f number of faults, the method comprising:

for each e-mail message to be stored, dividing the message into a mutable portion and an immutable portion, said mutable portion comprising that portion of the message data which is subject to change after the message has been stored, said immutable portion comprising that portion of the message which is not subject to change after the message has been stored; and

storing the message by;

storing the immutable portion of the message as immutable message data, f+1 times, to tolerate f number of failures; and

storing the mutable portion of the message as mutable message data, 2f+1 times, to tolerate f number failures, said mutable portion including a mutable pointer indicating where the immutable message data is stored.