Re: [Exim] How big can a mail file be??

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Autor: Nigel Metheringham
Data:  
A: Keith Pettit
CC: 'exim-users@exim.org'
Assumpte: Re: [Exim] How big can a mail file be??
kpettit@??? said:
> Now that I have it so every message will forward to one box I need to
> know how big that mail file can be and what I should read it with.


Assuming you are using mbox (or single file with multiple messages
format) the mail file can be up to the size that your OS allows - ie
commonly 2G on 32 bit systems. However you will hit performance
problems with this sort of file size - all deliveries have to be
serialised into it with a lock being created and dropped for each
message added as well as the actually message append and flush (on some
OSes at least a flush on a large file is a time consuming operation -
even if the append is quite small - this is a standard performance
problem on syslog for example).

If you are using a directory per mailbox, message per file format, then 
performance is basically limited by your filesystem directory 
performance, as is your total mailbox size (probably the limit will be 
when the directory reaches the maximum file size).  If you do this then 
you count messages by
    ls /path/to/mailbox |wc


this may run slowly (!) - adding the appropriate switch to your ls to
stop it sorting the output may help a lot.

    Nigel.


-- 
[ Nigel Metheringham                  Nigel.Metheringham@??? ]
[ Phone: +44 1423 850000                         Fax +44 1423 858866 ]