[ale] Sendmail latency

[Ryan Fish]

Where is the information returned by the "host" command obtained from???




----- Original Message ----- 
From: "Ryan Fish" <FishR at bellsouth.net>
To: "Atlanta Linux Enthusiasts" <ale at ale.org>
Sent: Monday, January 24, 2005 11:35 PM
Subject: Re: [ale] Sendmail latency


> > --- Ryan Fish <FishR at bellsouth.net> wrote:
> >
> > > > You are correct that sendmail (mail in general too) is heavily
> dependent
> > > > upon dns.  Ping alone doesn't necessarily test dns.  Can you 'host'
> each
> > > > machine name and ip successfully?
> > >
> > > - When I 'host' the app server from the mail server I only receive
> > > 192.168.3.0
> >
> > Hmmm, that should be a valid IP address (although .0 is probably
usable),
> > something like 192.168.3.1.
>
> - The actual IP for this app server is .221 so I have no idea why it is
> coming back as .0
>
> >
> > > - When I 'host' the mail server from the app server I receive the
full,
> > > proper IP address
> > >
> > > > Make sure that the order is files,dns when you
> > > > "grep hosts /etc/resolv.conf"
> > >
> > > - This results in no output on either server.  I know what you are
> looking
> > > for though but cannot remember the file to look in at this time...
> >
> > Sorry, I meant /etc/nsswitch.conf
>
> [root at mailserver mail]# grep hosts /etc/nsswitch.conf
> #hosts:     db files nisplus nis dns
> hosts:      files dns
>
> [root at appserver etc]# grep hosts /etc/nsswitch.conf
> #hosts:     db files nisplus nis dns
> hosts:      files dns
>
>
> >
> > > > How many emails does the java applet send at once?  Are we talking
> > > > hundreds or thousands?
> > >
> > > - Thousands.  When I spoke with the client around 8:30P EST tonight
> there
> > > were 7500 msgs in the queue used by the Java app on the App server.
> > > Typically that queue is cleared almost instantly.
> >
> > It could be that the sendmail queue is getting backlogged due to latency
> at
> > other (receiving) mail servers.  List would be indicated in the "stat"
> output
> > of each connection attempt in /var/log/maillog.   Check also for any
> errors in
> > /var/log/maillog indicating connection limiting due to high load
average?
>
> Everything worked fine prior to rebooting the app servers around 5A on
> 14JAN.  Afterwards all of this started...
>
> I see very few errors in the maillog.  Here is a sample of some:
>
> Jan 24 23:24:33 mailserver sendmail[5617]: j0LHsHCx010652:
> to=<user at outsidedomain.com>, delay=3+10:30:11, xdelay=00:00:00,
> mailer=esmtp, pri=7327408, relay=mail.outsidedomain.com. [38.113.1.50],
> dsn=4.3.0, stat=Deferred: 451-host lookup did not complete
>
> Jan 24 23:27:56 mcmail02 sendmail[5617]: j0LFWuTF026717:
> to=<user at otherdomain.com>, delay=3+12:54:55, xdelay=00:00:15,
mailer=esmtp,
> pri=7502182, relay=otherdomain.com. [38.161.171.51], dsn=4.0.0,
> stat=Deferred: Connection refused by otherdomain.com
>
>
>
> - I don't know how to obtain the 'stat' output of connections in
> /var/log/maillog...
>
> -Ryan
>
>
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