Mailing List Message #96212
From: Christian Ellsworth <>
Subject: Re: Your experiences - MBOX vs MDIR
Date: Tue, 23 Sep 2008 21:42:20 -0400
To: CommuniGate Pro Discussions <>
Shaun Gamble wrote:
Herbert Fischer wrote:



Despite all the facts and discussions we do about this two formats I would like to know more about your experiences on using both of this formats in CGP, including the file system used in any case. I know each one have advantages and disadvantages but most of the perceptions we only have in production environments.


I work in a ISP and host more than 1.5 million mailboxes and have all types of users using maildir format and some opensource adapted software.

We decided to go MBOX in CGP to reduce I/O on storages but we have raised some speculations on copy-on-write method used by ZFS, the choosen FS in this project.


The only real difference I've found is the folder size limit. Mbox can't allow a folder above 2GB. Mdir can. Otherwise, indexing has really sped mbox up and they're fairly equal, from my tests.

Well... for my experience, Mbox indexed from 3MB best way...

I don't personally recommend Mdir, it adds IO overhead to Filesystems, space overhead and the very nasty possibility of breaking the account when crossing the 32768 files on the the same folder...  in 100 messages per folder both should run almost equal... but when going over 2000 messages, scenario changes, and then over 10000 messages - believe me fellow admins -, things go downhill from there for mdir. again... this is OS limitation... specially when using Cluster filesystems, less but bigger files will perform better than a zillon small files... please ZFS groupies stay out of this one... ;-)

Christian  Ellsworth
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