Re: SLAPD denial of connections under load

[Pierangelo Masarati <ando@sys-net.it>]

Howard Chu wrote:

> Quanah Gibson-Mount wrote:
>
> > --On Wednesday, August 11, 2004 8:43 PM -0400 James Courtney 
> > <Jcourtney@inphonic.com> wrote:
>
>
> > > Our other problem is that under high load from the mail server we see
> > > that Maildrop claims it cannot connect to the LDAP server.  They are on
> > > the same system and Maildrop connects to localhost rather than going 
> > > out
> > > over the network and back.  Maildrop's ldap_simple_bind_s is 
> > > returning 81
> > > (0x51) which is defined as the constant LDAP_SERVER_DOWN.  The 
> > > server has
> > > been up for 24 hours now and is generally responsive though so this is
> > > confusing.  Under what conditions would slapd not accept a network
> > > connection?  Threads + backlog exceeded?
>
> > I suggest you separate the mail server from the LDAP server.  The 
> > high load on the system from the mail delivery agent may be 
> > preventing slapd from responding.
>
>
> There isn't enough information here to determine a course of action. 
> You need to get more info before making suggestions on how to fix the 
> problem.
>
> My guess is that slapd is out of file descriptors or there are too 
> many outstanding connections. Using a program like lsof may help to 
> determine if that's the case. There is no way that any mail server can 
> generate more queries than slapd can handle when both are running on 
> the same CPU.

My 2c: when slapd is unable to serve an MTA, usually you need to craft
your backend's indices.  I really don't see a scenario where looking up
an indexed key takes longer than handling an email.

Ciao, p.




   SysNet - via Dossi,8 27100 Pavia Tel: +390382573859 Fax: +390382476497