[EMAIL PROTECTED] wrote:
On Oct 30, 2008, at 2:35 PM, [EMAIL PROTECTED] wrote:
Maildir is nice compared to mbox but it really isn’t optimal. In days
where IOPS is the most difficult resource to get into your server (and
dovecot already using close to nothing in terms of CPU time and
memory)
having one file per e-mail is less than sub-optimal especially when a
large amount of users just downloads the whole mailbox using POP3
(not to
mention backing up Maildirs).
It seems to me that a database like Postgres or MySQL would be the
best bet.
That's a matter of opinion. Moving mail storage to a database would
probably be the last thing I would ever do (I'm not saying it's not the
right thing for some people. I'm just not one of them).
I'm using mysql for storing the users database but that’s another story.
Adding a database is one additional level of complexity. One more program
to govern. In my opinion it's nice to know that as long as the disk is
readable nothing can go completely wrong.
I have to jump in here and go a bit tangential by saying there are
databases and want-to-be's.
The database in my case would be roughly 400 GB holding some 60 million
records.
Fair sized but not really big.
Just imagine if one single byte got written to the wrong place. Power
outage, OS crash, software bug or whatever could easily result in this (I
regularly experience mysql tables that crash on their own from heavy use).
Having to run a repair on a table of that size whilst all users are eager
to get to their data must be a nightmare of proportions.
There is the difference between an enterprise database and MySQL. Yes,
yes, yes lots of /enterprises/ run applications that use MySQL but most
of those apps have throw away data or they are not using the free
version of MySQL.
Just imagine backing the thing up, exporting 60.000.000 SQL queries.
Not to say importing them again if something should go really wrong.
Actually I'n not even sure it would be faster. When the index files grow
to several gigabytes they kind of loose their purpose.
There are many businesses backing up way-more data than that and it it
isn't 60,000,000 queries -- it is one command. But if you use serious
hardware "backing up" isn't really needed. RAID, redundant/hot-swap
servers, etc. make backing up /extra redundancy/. :-)
And I bring this up because "Archiveopteryx"
<http://www.archiveopteryx.org/> uses a database - PostgreSQL.
Rod
--
Maildir is very resilient to various errors. It is virtually impossible to
corrupt a maildir (at least I've never experienced anything).
Also you can backup up the thing without worrying about anything accessing
it at the same time.
Mbox less so but still a lot better than having one huge database.
Dbox would be the ultimate compromise between crash resilience and a low
number of files (not to mention the enormous potential for speed gains).
Regards, Mikkel
