Korey,
Did you say that before?? Sorry, I never saw that (or don't remember seeing
it). I also never saw a response to my question about the numbers reported
at the end of the POP3 connection message, when you attempted to login
during the 'problem'!?
My theory (and I don't have hard evidence to back it), is that the POP3
server makes the requests to SQL, and over time, SQL start slowing down (see
your own resource info from earlier), which causes more resources to be
demanded by POP3 (connections not closing in timely fashion), which further
slows SQL, until eventually, responses are so slow that you see the symptom
of 'cannot login'. The restart breaks the SQL connection, and frees up both
SQL (not sure of this, but eventually the old requests should die) and POP3
resources that were used. Upon startup, new POP-SQL connection is created
and things are OK, but the cycle starts again.
Maybe what Bob said about SQL time to reply, is also a clue and should be
looked at in your situation. It is good upon establishing the connection,
but because of resource demands, over time degrades until some 'magic' value
is reached and from there, things go south really fast.
I don't have the needed resources or time to test this theory, but I think
it fits the facts and observations I have heard, here in the forum.
The only other thing I have heard, but was on SMTP Auth and external DB, was
that if one waited a period of time, the situation would seem to clear up
and responses were seen. Maybe in some situations, POP3 is 'more sensitive'
than SMTP is/was? Maybe if you could block the port for a while, you could
simulate this.
Oh, one other thought. The swap file size this computer. Is it at least
1.5xRAM? I've heard recommendations that say 2-3xRAM is much better and
better still, split across multiple drives.
Daniel Donnelly
________________________________________________________
----- Original Message -----
From: "Korey Verlsteffen" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, April 19, 2001 2:13 PM
Subject: Re: [IMail Forum] POP3 hangs w/external SQL database
> One more point that I must make is that with all this happening why would
> restarting just the pop3 service fix the problem??
>
>
>
> ----- Original Message -----
> From: "Daniel Donnelly" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Thursday, April 19, 2001 12:28 PM
> Subject: Re: [IMail Forum] POP3 hangs w/external SQL database
>
>
> > Korey,
> >
> > I think your conclusion is not 100% correct! Many others here in the
forum
> > have found that SQL is a resource hog and have recommended it _not_ be
> > running on the same machine as IMail. Along with many other
> recommendations
> > for the hardware needs for the SQL machine. At least one user indicated
he
> > had separate machines and over 50K users and had no problems with IMail
or
> > SQL. That would seem to tell me, the ODBCUSER.DLL is OK.
> >
> > And your further information about POP logins to domains with and
without
> > SQL, seem to confirm that POP3 service is working fine. This would
> indicate
> > to me, that the problem is getting responses back from SQL, when POP3
asks
> > for them.
> >
> > If you are happy with IMail DB, fine. If not, they I (using
> recommendations
> > sent by other forum members) would suggest you consider a separate
machine
> > for SQL and another for IMail. It sounds like your current machine might
> > qualify for the SQL machine and maybe a less powerful one is needed for
> > IMail, but that may depend on the number of users you have.
> >
> > Below is that other persons email:
> >
> > Subject: RE: [IMail Forum] For those using MS SQL
> >
> > I agree, SQL runs better on W2K, when properly configured! I have been
> > following the SQL thread here for quite some time and, frankly, there is
a
> > LOT of mis-information going around. A couple of quick points if I may.
> This
> > is long but, I had to say it....
> >
> > First, after Mike Nice was gracious enough to share his re-worked
> > ODBCUSER.DLL, external database use with Imail and SQL servers became a
> > reality. Thanks to Ipswitch for incorporating that code in recent
> releases.
> > While some work still could be done in the multi-threading area, it
works
> as
> > is.
> >
> > Second, the one biggest and most important performance issue when using
> > Imail with an external database and SQL is NOT the Imail box, it's the
SQL
> > box and it's network connectivity.
> >
> > I know, your saying "but I've got a Pentium 4 and a zillion megs of RAM,
> > etc..." and it still does not work.... Well, lets look at a few issues
> > shall we? First, never, never, never (did I make that plain enough?)
run
> > SQL on the same machine as Imail, just don't do it, SQL running with
Imail
> > will seriously degrade Imail's performance, that's just the nature of
> > database servers, they want it all... Let them have it all, run SQL on
> it's
> > own server, nothing else running with it.
> >
> > Hows your network working? Are you running in a switched Ethernet
> > environment? You should be, 100mbs, full duplex. Do you monitor LAN
> traffic?
> > You should. If your still running 10mbs, half duplex through standard
> hubs,
> > UPGRADE! The Imail box and the SQL server can only process packets as
fast
> > as they arrive. Remember, Ethernet trashes packets when they collide and
> has
> > to resend. The higher the collision rate on your LAN, the lower the
> overall
> > performance. Get a switch, buy some new 100 mbs cards and join the new
> > century...
> >
> > How's your SQL box configured? A fast processor won't help if the RAM
is
> > not there or, the I/O and disk access is slow. Avoid the temptation to
> buy
> > huge IDE hard drives, drive access time suffers, no matter what the
> > manufacturer says. Run SCSI, boot from IDE if you must but, use SCSI
> drives
> > for SQL and it's data. And about RAM, 500 plus megs, PC 100 or higher
> DIMMS,
> > no SIMMS, run at processor bus speed, especiall on the SQL box, period.
> >
> > Beware of RAID! There are some cheap RAID controllers out there that
will
> > severly slow performence in RAID 5 configurations. Sure its nice to have
> > RAID 5 but, count on the overhead to slow you down. Again, if you must
use
> > RAID, spend the money for a quality controller.
> >
> > Is your NT on W2K installation tuned for best performence? Foreground
> apps
> > should have minimum priority (performence boost) and background and
> server
> > apps should have maximum. Set up for maximum boost for "networking
apps",
> > not "file sharing" and certainly not "load balancing"
> >
> > Even if you have all the RAM in the world, increase your swap file size,
> NT
> > will still use it and bigger is better. A general rule of thumb is to
> double
> > whatever NT recommends.
> >
> > Having run Imail servers since version 2 (i believe, long time ago) we
> have
> > found the software to be quite stable and resilant, if you give it a
fast
> > environment to work in. If you have the means, test the time your SQL
box
> > takes to authenticate a database request. Anything over 20ms is telling
> you
> > something is wrong! We have found that, SMTP AUTH especially, will fail
or
> > severly degrade if it does not get an IMMEDIATE answer from the SQL
> server.
> > Consider this when pulling you hair out because users are getting a
> password
> > request box when sending mail using SMTP AUTH.
> >
> > Oh, and how's your PDC performing? If it running over 25% utilization
for
> > any 30 second period, upgrade it! Remember, an NT network is only as
good
> as
> > all the machines that make it a network, PDC and BDC's included...
> >
> > That's, it, flame away but these observations come from running Imail
and
> > SQL in a 50,000+ user environment on all kinds of hardware and network
> > topology.
> >
> > Robert J Fehn Sr. CEO, Senior Engineer
> > ProNet USA Inc. www.pro-usa.net
> >
> >
> > Daniel Donnelly
> > ________________________________________________________
> >
> > ----- Original Message -----
> > From: "Korey Verlsteffen" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Thursday, April 19, 2001 10:16 AM
> > Subject: Re: [IMail Forum] POP3 hangs w/external SQL database
> >
> >
> > > The machine is a quad xeon w/1gb of ram running Imail and SQL on the
> same
> > > machine. We decided to drop the SQL database and move the users to
the
> > > Imail internal db since there are just too many problems with external
> > > databases and Imail. Problem solved.
> > >
> > > Just for the record I did notice that when users could no longer pop
> into
> > > the server I was able to pop into one domain that we had setup using
the
> > > internal Imail db. While other domains on the same server using the
> > > external db could not. Doing some further pd when I opened a pop3
> session
> > > all went well until I sent the pop3 login info for a domain using an
> > > external db, then the session would hang. If I opened another pop3
> > session
> > > and submitted a pop3 login for a domain using the internal imail db it
> > works
> > > perfectly. Looks like a problem with the odbc drivers that Imail
uses.
> > >
> > >
> > >
> > > ----- Original Message -----
> > > From: "Daniel Donnelly" <[EMAIL PROTECTED]>
> > > To: <[EMAIL PROTECTED]>
> > > Sent: Tuesday, April 17, 2001 4:58 PM
> > > Subject: Re: [IMail Forum] POP3 hangs w/external SQL database
> > >
> > >
> > > > Korey,
> > > >
> > > > What are the numbers at the end of the connect response line? If the
> > last
> > > > one is more than say 5-10, then something is not closing down the
pop3
> > > > connections.
> > > >
> > > > Is the SQL on the same machine? What is the hardware for the IMail
> > > machine?
> > > >
> > > > Others here have indicated that SQL uses all the resources it can
get,
> > > > which, if on the IMail machine, might limit its access to resources
> and
> > be
> > > > the cause of your trouble.
> > > >
> > > > Daniel Donnelly
> > > > ________________________________________________________
> > > >
> > > > ----- Original Message -----
> > > > From: "Korey Verlsteffen" <[EMAIL PROTECTED]>
> > > > To: <[EMAIL PROTECTED]>
> > > > Sent: Tuesday, April 17, 2001 9:28 AM
> > > > Subject: [IMail Forum] POP3 hangs w/external SQL database
> > > >
> > > >
> > > > > Ok, here is the situation.
> > > > >
> > > > > My setup consists of a win 2000 server with Imail 6.06 all patches
> > > > included
> > > > > and SQL 2000. Imail is setup to use and external db with virtual
> > hosts.
> > > > The
> > > > > problem that I am having is that pop3 stops responding just about
> > every
> > > > > hour. A simple net stop pop3d32 and start brings imail back
online,
> > but
> > > > > only for another hour or so. When this happens I can telnet to
port
> > 110
> > > > and
> > > > > I will get the standard response but it will not accept any
> commands.
> > > > Once
> > > > > this happens pop3d32.exe gradually consumes more and more cpu
usage
> > > until
> > > > > its restarted.
> > > > >
> > > > > Any suggestions?
> > > > >
> > > > > Korey
> > > > >
> > > > >
> > > > > Please visit http://www.ipswitch.com/support/mailing-lists.html
> > > > > to be removed from this list.
> > > > >
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> > > > >
> > > >
> > > >
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