Re: [SLUG] Redundant Email systems
I recon you could do it by setting a real big value on the mx record of the secondary box. Set up the server so that any mail (should be almost never) it receives are fired off back at your primary as well as being locally delivered This way the secondary box grabs mail if the primary is down. When the primary comes up, the messages are fired off back at the primary (assuming it hasn't been down for too long). This means users may get some messages twice. The record for mail.whatever.com may have to be changed manually...(or maybe the same thing as with the mx records could be done) so set time to live at like 15mins. Optionally if you wanted mail not downloaded to be on the secondary, a regular (i.e. every 10mins or so) rsync over ssh of the local mail directories from the primary to the secondary could be done... John Ferlito wrote: > > On Tue, Oct 24, 2000 at 10:07:23AM +1000, Marshall, Joshua wrote: > > Does anyone know of a good method to make an email system redundant, so > > that if one server goes down (power loss, network loss etc) the users > > can still retrieve and send emails ? > > Send emails shouldn't be too much of a problem. You can setup > something like heartbeat todo ip takeover and pretend to be the outgoing > mail server for a bit. Recieving is really difficult though. Almost > impossible because you would end up with mail spools in two different > places when the other box comes up and you would have to find a pop > client that would deal with that. Unless you have a third box which NFS > servers /var/spool/mail then you could setup both boxes as primary MX's > and allow either of them to deliver. But you need to make sure you get > locking right. > > -- > John > > The difference between a good man and a bad one is the > choice of cause - William James > > -- > SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ > More Info: http://slug.org.au/lists/listinfo/slug -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://slug.org.au/lists/listinfo/slug
Re: [SLUG] Redundant Email systems
On Tue, 24 Oct 2000, John Ferlito wrote: > mail server for a bit. Recieving is really difficult though. Almost Some sort of fetchmail config? Mikal -- Michael Still ([EMAIL PROTECTED]) - Panda PDF Generation Library (http://www.stillhq.com/panda/) - GPG Public Key at http://www.stillhq.com/mikal.asc -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://slug.org.au/lists/listinfo/slug
Re: [SLUG] Redundant Email systems
I'm using procmail to deliver to Maildir format - which is what Qmail uses. The clients use either POP or IMAP (Most prefer IMAP) I found an article ( http://www2.linuxjournal.com/lj-issues/issue73/3778.html ) which describes how to use software raid across the network, I'm going to see what can be done with something similar, and heartbeat software to fail over to the other machine. I prefer machine redundancy over item redundancy within a machine as it is a completely separate system and easily replaceable. Wish me luck :) Umar Goldeli wrote: > Locking? > > Qmail. > > Need I say more? :) -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://slug.org.au/lists/listinfo/slug
Re: [SLUG] Redundant Email systems
> places when the other box comes up and you would have to find a pop > client that would deal with that. Unless you have a third box which NFS > servers /var/spool/mail then you could setup both boxes as primary MX's > and allow either of them to deliver. But you need to make sure you get > locking right. Locking? Qmail. Need I say more? :) //umar. -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://slug.org.au/lists/listinfo/slug
RE: [SLUG] Redundant Email systems
I would be concerned about file locking if the mail files are on NFS. If the primary machine goes down, there are no guarantees that it will release the NFS locks before it goes down, and you would be just left with the same problem as before. I would have instead chosen a redundant hardware configuration with only one effective machine being the mail spooler. This machine could use a RAID-1 or 5 hot swap hardware arrangement so that if one disk fails, you don't use the lot. Hot swap CPUs would be nice but even more expensive. It all depends on how much you need the thing to be up. If you go for redundant disks, say, but non-redundant CPU, then for the short time a failed processor is down (of course you have a spare on hand) your ISP just caches incoming mail and your users cache outgoing mail. When you plug in the new CPU (or whatever it was that failed) the thing just starts up again on the same disks as before and everyone should be able to retrieve / send their mail again. Well that's the theory anyway. Loss of power: use a UPS for a while or for short outages, then rely on ISP caching until you can reconnect. Regards, Jill. ___ Jill Rowling Snr Design Engineer & Unix System Administrator Electronic Engineering Department, Aristocrat Technologies Australia 3rd Floor, 77 Dunning Ave Rosebery NSW 2018 Phone: (02) 9697-4484 Fax:(02) 9663-1412 Email: [EMAIL PROTECTED] -Original Message- From: John Ferlito [mailto:[EMAIL PROTECTED]] On Tue, Oct 24, 2000 at 10:07:23AM +1000, Marshall, Joshua wrote: > Does anyone know of a good method to make an email system redundant, so > that if one server goes down (power loss, network loss etc) the users > can still retrieve and send emails ? Unless you have a third box which NFS servers /var/spool/mail then you could setup both boxes as primary MX's and allow either of them to deliver. But you need to make sure you get locking right. -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://slug.org.au/lists/listinfo/slug
Re: [SLUG] Redundant Email systems
On Tue, Oct 24, 2000 at 10:07:23AM +1000, Marshall, Joshua wrote: > Does anyone know of a good method to make an email system redundant, so > that if one server goes down (power loss, network loss etc) the users > can still retrieve and send emails ? Send emails shouldn't be too much of a problem. You can setup something like heartbeat todo ip takeover and pretend to be the outgoing mail server for a bit. Recieving is really difficult though. Almost impossible because you would end up with mail spools in two different places when the other box comes up and you would have to find a pop client that would deal with that. Unless you have a third box which NFS servers /var/spool/mail then you could setup both boxes as primary MX's and allow either of them to deliver. But you need to make sure you get locking right. -- John The difference between a good man and a bad one is the choice of cause - William James -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://slug.org.au/lists/listinfo/slug
[SLUG] Redundant Email systems
Does anyone know of a good method to make an email system redundant, so that if one server goes down (power loss, network loss etc) the users can still retrieve and send emails ? -- SLUG - Sydney Linux User Group Mailing List - http://slug.org.au/ More Info: http://slug.org.au/lists/listinfo/slug
