Using a low DNS TTL is not a very reliable method for ensuring failover via DNS update. Most large DNS shops will not honor TTL's below a certain threshold - 12hrs, 1 day, etc..
Matt Pavlovich > From: Theo Cabrerizo Diem <[EMAIL PROTECTED]> > To: Lars Holmstr�m <[EMAIL PROTECTED]> > Cc: [EMAIL PROTECTED] > Subject: Re: [courier-users] Disaster tolerant IMAP and SMTP ? > Date: 12 Jul 2003 12:57:02 -0300 > > You can have two address entries in your DNS to imap.foo.bar > in BIND : > > imap IN A 1.2.3.4 > imap IN A 4.3.2.1 > > This will do a round-robin load balancing ... and when some server goes > down .. maybe you can't get a response, but if you retry the other one > will get the request. > > The problem is : both imap server must access the same storage for > messages ... or this storage must be mirrored across internet ... > > if yu don't like of round-robin, you can set a TTL of 2 seconds in your > DNS and a script that detect the server failure and updates the DNS > record. but the problem of storage still remains. > > []'s > > On Sat, 2003-07-12 at 09:27, Lars Holmstr�m wrote: > > I consider building a disaster tolerant mailsystem for in and outgoing > > mail. > > > > I already have two ISPs and MX records that direct incoming > > mailtraffic properly. > > > > The problem seems to be the IMAP. > > > > Does any one have a suggestion for how to do this ? > > > > /Lars > > Ps. Disaster tolerant in my view is when I can afford to loose one > > computerroom completely and the service from a users perspective is > > still available. Ds. > > > > ______________________________________________________________________ > From: andrew <[EMAIL PROTECTED]> > To: [EMAIL PROTECTED] > Subject: Re: [courier-users] newbie install > Date: 12 Jul 2003 12:52:07 -0400 > > I've installed courier 0.42.2 on RH8 following the instructions. > > I'm just curious about something. > > It seems that there is a complete installation of courier in: > > /usr/lib/courier/ > > and in > > $HOME/courier-0.42.2/courier/ > > Why is it in both locations? > > TIA, Andrew > > > > ______________________________________________________________________ > From: andrew <[EMAIL PROTECTED]> > To: [EMAIL PROTECTED] > Subject: [courier-users] testing my first installation > Date: 12 Jul 2003 13:12:54 -0400 > > I'm following the courier0.42.2 installation testing and attempted to run > "perftest1" against my test account. > > I started courier and authdaemond without any errors in the log, but when I > tried to execute the perftest1 (as root), I saw in the terminal window: > > 450 Service temporarily unavailable. > andrew-test-1: invalid address > > 450 Service temporarily unavailable. > andrew-test-2: invalid address > > ...etc. through 'andrew-test-5'..it looked like it ran about 1000 times. > > my user account is 'andrew' > > I want to use mySQL for authentication but haven't set it up yet. My > authdaemond has the unmodified default setup. > > TIA, Andrew > > > > > ______________________________________________________________________ > From: Lars Holmstr�m <[EMAIL PROTECTED]> > To: [EMAIL PROTECTED] > Subject: Re: [courier-users] Disaster tolerant IMAP and SMTP ? > Date: 12 Jul 2003 19:10:04 +0200 > > The question is about how to create a distributed imap-server with a > multiple site storage. > /Lars > ----- Original Message ----- > From: James A Baker > To: [EMAIL PROTECTED] > Sent: Saturday, July 12, 2003 5:51 PM > Subject: Re: [courier-users] Disaster tolerant IMAP and SMTP ? > > On Saturday, Jul 12, 2003, at 07:27 US/Central, Lars Holmstr�m > wrote: > > I consider building a disaster tolerant mailsystem for > in and outgoing mail. > > I already have two ISPs and MX records that direct > incoming mailtraffic properly. > > The problem seems to be the IMAP. > > Does any one have a suggestion for how to do this ? > > /Lars > Ps. Disaster tolerant in my view is when I can afford > to loose one computerroom completely and the service > from a users perspective is still available. Ds. > > Is your question about how to initially create a redundant > IMAP data store across your server rooms? Or how (after it's > all created) to let users reach it automatically, regardless > of which computer room is still alive after a failure? > > I.e. Server implementation vs. DNS implementation? (...or > both?) > > -jab > > > ______________________________________________________________________ > From: Mitch (WebCob) <[EMAIL PROTECTED]> > To: Lars Holmstr�m <[EMAIL PROTECTED]>, > [EMAIL PROTECTED] > Subject: RE: [courier-users] Disaster tolerant IMAP and SMTP ? > Date: 12 Jul 2003 12:04:12 -0700 > > You've got a few things to look into Lars - this isn't really a > courier question... > > You need to look at distributed replicated storage systems (afs, coda, > or simply replicated NFS...) which are all off topic.... > > Then you need to decide your method for connection failover - DNS with > recrd updates when a node fails is probably your best bet if you are > operating on different networks... you can expect your data transfer > volume to be doubled though - as ever file that is created or moved on > one system has to be transfered to the other system... > > m/ > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Behalf Of > Lars Holmstr�m > Sent: July 12, 2003 10:10 AM > To: [EMAIL PROTECTED] > Subject: Re: [courier-users] Disaster tolerant IMAP and SMTP ? > > > The question is about how to create a distributed imap-server > with a multiple site storage. > /Lars > ----- Original Message ----- > From: James A Baker > To: [EMAIL PROTECTED] > Sent: Saturday, July 12, 2003 5:51 PM > Subject: Re: [courier-users] Disaster tolerant IMAP > and SMTP ? > > On Saturday, Jul 12, 2003, at 07:27 US/Central, Lars > Holmstr�m wrote: > > I consider building a disaster tolerant > mailsystem for in and outgoing mail. > > I already have two ISPs and MX records that > direct incoming mailtraffic properly. > > The problem seems to be the IMAP. > > Does any one have a suggestion for how to do > this ? > > /Lars > Ps. Disaster tolerant in my view is when I can > afford to loose one computerroom completely > and the service from a users perspective is > still available. Ds. > > Is your question about how to initially create a > redundant IMAP data store across your server rooms? Or > how (after it's all created) to let users reach it > automatically, regardless of which computer room is > still alive after a failure? > > I.e. Server implementation vs. DNS implementation? > (...or both?) > > -jab > > > ______________________________________________________________________ > From: Mitch (WebCob) <[EMAIL PROTECTED]> > To: andrew <[EMAIL PROTECTED]>, [EMAIL PROTECTED] > Subject: RE: [courier-users] newbie install > Date: 12 Jul 2003 12:04:35 -0700 > > Because when you INSTALL something, the files are COPIED to the the INSTALL > location... > > Your home / build directory is like the CD source for a windows program - when > you "make install" it is copied to the running location - when you are done, you > don't need the copy under $HOME any more. > > m/ > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] Behalf Of andrew > > Sent: July 12, 2003 9:52 AM > > To: [EMAIL PROTECTED] > > Subject: Re: [courier-users] newbie install > > > > > > I've installed courier 0.42.2 on RH8 following the instructions. > > > > I'm just curious about something. > > > > It seems that there is a complete installation of courier in: > > > > /usr/lib/courier/ > > > > and in > > > > $HOME/courier-0.42.2/courier/ > > > > Why is it in both locations? > > > > TIA, Andrew > > > > > > > > ------------------------------------------------------- > > This SF.Net email sponsored by: Parasoft > > Error proof Web apps, automate testing & more. > > Download & eval WebKing and get a free book. > > www.parasoft.com/bulletproofapps1 > > _______________________________________________ > > courier-users mailing list > > [EMAIL PROTECTED] > > Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users > > > > > > > > ______________________________________________________________________ > _______________________________________________ > courier-users mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/courier-users -- Matt Pavlovich <[EMAIL PROTECTED]> Allegiance Telecom, Inc. ------------------------------------------------------- This SF.Net email sponsored by: Parasoft Error proof Web apps, automate testing & more. Download & eval WebKing and get a free book. www.parasoft.com/bulletproofapps1 _______________________________________________ courier-users mailing list [EMAIL PROTECTED] Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
