Re: virtualizing local users

From: Phil Howard (no email)
Date: Tue Jul 02 2002 - 05:15:48 EDT


On Tue, Jul 02, 2002 at 07:50:30AM +0200, Ralf Hildebrandt wrote:

| > 3. NOT one giant map with every user at domain dot That will be too big to
| > maintain. A separate map for each domain is best.
|
| That's what you think.
| It performs best wiuth one map (which can be constructed/merged from
| many small map). OTOH, sql or LDAP come to mind.

Accessing one large map is faster than accessing one smaller map? If
that's true, then I'll add a million dummy entries to make it faster.

Actually, the performance of accessing the map isn't the reason I want
to split by domain. It's a maintenance issue. Suppose there are 1000
domains with an average of 500 users each. The program that generates
the maps when there is a change would be exposed to 1000 times more
updates, and have 1000 times more work to do, each time a change is
made. That's O(N^2) for N = number of domains. Then there is the
issue of maintenance permission per domain. I need to leave open the
possibility that different domains will be managed by different user
access permissions. That might become part of the design.

| > 5. If ${prefix}/${domain}/${user}/ exists, the address is valid for
| > delivery. If it doesn't, then the address is non-existant.
|
| Interesting. That would be using the FS as map.
| In that case, smtpd couldn't run chrooted.

Why not? I think it can be. Linux's bind mounts work fine across
chroot.

| > To carry out some of these things, the thought I had was to write a new
| > map type handler which does a lookup for an existing directory or file.
|
| It already exists (I thinK!) as a patch.

I'll look around for it.

-- 
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| Phil Howard - KA9WGN |   Dallas   | http://linuxhomepage.com/ |
|  | Texas, USA | http://phil.ipal.org/     |
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