Re: Hashed mailboxes ?

[Tom Samplonius <tom@sdf.com>]

On Tue, 19 Nov 1996, Alexandre Sidorenko wrote:

> Hi,
> 
> does anybody know about some local delivery agent to make mailboxes
> 'hashed' too, i.e. instead of /var/spool/mail/asid use something like
> /var/spool/mail/a/s/asid ? The latest 'qpopper' supports such mailboxes
> structure, and it is vital for big sites with more than 10,000 clients. I
> have found that Zmailer till now supports hashing for queue spool only. I
> can probably hack 'mailbox' transport, but maybe this feature is already
> done by somebody ? 
> 
> With best regards,
> 
> -------------------------------------------------------------
> Alexandre Sidorenko		Senior System Administrator
> asid@microtec.net
> Internet Microtec, Montreal, QC
> -------------------------------------------------------------
> 
> 
> 

  The common way to solve this is to put mailboxes into user home
directories.

  Also, I did some tests on this, I found no problems with mail spools
with 30,000+ mailboxes.  The time to open one file in a directory with
30,000 other files, is not that much slower than a directory with a 1000
files in it.  This is somewhat os dependant though.

  A much bigger problem is how i/o inefficient Qpopper is.  Qpopper opens
a mailbox, and copies it to a new file while scanning it for "\nFrom ".
So, if you open a 10MB mailbox, it copes 10MB to a new file, then reads
the 10MB again, and sends it to the POP client.  The regular mbox format
is horrible, and basically requires this.  This also explains why mail
clients timeout while opening large mailboxes.

  A tool like Cyrus solves both of these problems.  It allows your to
spread mailboxes over multiple partitions, and indexs the mail at
delivery, so opening a 50MB mailbox is nearly as quick as opening a 5MB
mailbox.

Tom