Re: slow IMAP connection

Tim,

Tim Mooney wrote:
> In regard to: Re: [Imap-uw] slow IMAP connection, Bob Atkins said (at...:
>
>> The only way to fix the slow I/O problem, especially with large mail 
>> boxes is to convert to mix format. mbx format is only marginally 
>> better than mbox from a performance standpoint. This is from my 
>> personal experience of having mail boxes with 40,000+ messages and 
>> >2GB in size.
>
> This brings up a question I've had: both traditional format and MBX run
> into issues when they cross the 2 GiB boundary, because of signedness
> issues in the UW code.  I realize a MIX folder is composed of multiple
> files, but does that mean that the 2 GiB is not a problem for MIX?
Yes, that is correct. The mix format consists of many files in a 
directory. A refinement of the maildir concept which was flawed because 
it created a separate file for /_each_/ message. mix creates files that 
contain multiple messages and a mix file will never get to >2GB in size 
so that 2GB boundary problem is solved. I believe that the default file 
size for mix is 1MB. Any message larger than 1MB will be the only 
message in a file however, the many smaller messages will fill up to 1 
MB file before another file is started. All of the messages are indexed 
into an index file(s) which contains all of the subject headings and 
status info which makes access /_very_/ fast. FYI, we implemented our 
mix solution using 10MB files rather than the default 1MB size because 
we felt that would be a more efficient file size and it has proven to 
work very well. As those who went down the maildir path (with another 
imap server) have painfully discovered - directories with too many 
inodes are very slow to search. mix is a great balance between not too 
many inodes and keeping file sizes and linear search runs to a minimum.

---
Bob

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