Re: [gentoo-user] Server Mirroring...
For the mail, I would use remote mounts for the directories that matter, so, if your server goes down, you can script and/or use tools to change the mount dir to another server that is kept rsynced (or another similar tool) with the down server... This is easy job, you just have to somehow monitor the activity and generate alerts about failures (mostly I use scripts with cron jobs). Of course this would require at least 3 machines and a fast LAN... MySQL replication features combined with DNS would allow you to rapidly exchange servers in case of failure, I have a mirror of my mysql server replicating as slave, it can be turned into master while I manage the actual master, syncing both is pretty easy and changing master/slave status too. -- Daniel da Veiga Computer Operator - RS - Brazil -BEGIN GEEK CODE BLOCK- Version: 3.1 GCM/IT/P/O d-? s:- a? C++$ UBLA++ P+ L++ E--- W+++$ N o+ K- w O M- V- PS PE Y PGP- t+ 5 X+++ R+* tv b+ DI+++ D+ G+ e h+ r+ y++ --END GEEK CODE BLOCK-- -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Server Mirroring...
Sascha Lucas wrote: easy with postfix: DNS round robin (solution inside DNS Server, nearly all MTAs are aware of this) So DNS round robins between the two mail servers. A new mail comes into server1, how does this mail make it to server2. Yes this is definitely the difficultest part. It must be solved somewhere in the LDA (cyrus). The MTA just pass mails to the LDA. So round robin should work. Sure round robin works for incoming mail from other ISP's. But what about users trying to send mail that happens to get the DNS for the down server? Or trying to check your mail and hitting the down server? Or the server without your mail? DNS round robin is useful in many cases, but I'm not convinced it solves the problem we're looking at. I don't see that Postgres supports multiple masters either. Circular I'm not an expert but what about this? http://www.postgresql.org/about/news.289 Ah forgot about that package. Only saw the Slony stuff. However after thinking about it a bit, I don't see why you'd need multi-master. Can you elaborate? The storage has to reside somewhere. If that site goes down, both servers go down. You either need both servers in the same site with shared storage or figure out how to do a shared nothing backend. It depends on how both sites are connected. Just like redundancy in Servers/Network you can have redundant storage. I.E. with (a)synchronous replication over IP or FC-networks. If you're replicating or copying to another site with completely different hardware then that fits the description of shared nothing. So either you're mounting the same storage or your mounting different storage in both locations. If you're mounting the same storage then one site can lose connection to it. BTW: I don't know a cluster-solution with cyrus. We use a cluster aware commercial one. Does the cluster aware stuff assume shared storage with both servers active/active or active/passive? I hate to be the guy shooting holes in everyone's ideas, but fault tolerant system design is a large part of what I've been doing for the past six years. It's not easy, it's not simple, and there are 254,861 caveats to any plan based on the services you're supporting, network size, skill of the local admins, and a hundred other things. Part of the problem is that the original poster left the field wide open and we're all making a number of assumptions. The emails so far indicate that there is no perfect solution in this case. Any fault tolerant design is going to require some trade offs. The original poster needs to decide what's important. Is better uptime more important than throughput? Is cost a factor? Is data integrity more important than uptime? kashani -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Server Mirroring...
Arturo 'Buanzo' Busleiman wrote: kashani wrote: Can you use maxdb as the backend for the mail system? It looks like you can build support for MaxDB into PHP, but Postfix, Courier, Cyrus, etc may be more problematic. It's mysql, actually. It should work easily, I guess. Er... well there is Mysql and Mysql Maxdb. My understanding is that maxdb is an entirely different code base. I can't see how it could be a drop in replacement for Mysql especially for binaries compiled against shared libs. kashani -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Server Mirroring...
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 kashani wrote: > Can you use maxdb as the backend for the mail system? It looks like you > can build support for MaxDB into PHP, but Postfix, Courier, Cyrus, etc > may be more problematic. It's mysql, actually. It should work easily, I guess. - -- Arturo "Buanzo" Busleiman - www.buanzo.com.ar Consultor en Seguridad Informatica / Dominio Digital TV - Da FOSS man! KTP Consultores - info AT ktpconsultores.com.ar Romper un sistema de seguridad los acerca tanto a ser hackers como el encender autos puenteando los convierte en ingenieros automotrices. -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.1 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDd9MWAlpOsGhXcE0RAhe9AJ0U6wpwyHzfBYVJtolJS1YPnyVsDwCggcJ6 8xjBZHk/FZlj6y9EE7qmJys= =KdCT -END PGP SIGNATURE- -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Server Mirroring...
easy with postfix: DNS round robin (solution inside DNS Server, nearly all MTAs are aware of this) So DNS round robins between the two mail servers. A new mail comes into server1, how does this mail make it to server2. Yes this is definitely the difficultest part. It must be solved somewhere in the LDA (cyrus). The MTA just pass mails to the LDA. So round robin should work. I don't see that Postgres supports multiple masters either. Circular I'm not an expert but what about this? http://www.postgresql.org/about/news.289 The storage has to reside somewhere. If that site goes down, both servers go down. You either need both servers in the same site with shared storage or figure out how to do a shared nothing backend. It depends on how both sites are connected. Just like redundancy in Servers/Network you can have redundant storage. I.E. with (a)synchronous replication over IP or FC-networks. BTW: I don't know a cluster-solution with cyrus. We use a cluster aware commercial one. Sascha. -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Server Mirroring...
Arturo 'Buanzo' Busleiman wrote: Sascha Lucas wrote: mysql: not "multi master" ready, just redundancy "master->slave", try postgres Why not try MaxDB? Is not in portage yet, but see this description: MaxDB is a re-branded and enhanced version of SAP DB, SAP AG's open source database. It is a heavy-duty, SAP-certified open source database that offers high availability, scalability and a comprehensive feature set. MaxDB complements the MySQL database server, targeted for large mySAP ERP environments and other applications that require maximum enterprise-level database functionality. It is available for a wide range of platforms, including Linux on several different architectures and Windows. http://freshmeat.net/projects/maxdb Can you use maxdb as the backend for the mail system? It looks like you can build support for MaxDB into PHP, but Postfix, Courier, Cyrus, etc may be more problematic. kashani -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Server Mirroring...
Sascha Lucas wrote: Just some keywords: easy with postfix: DNS round robin (solution inside DNS Server, nearly all MTAs are aware of this) So DNS round robins between the two mail servers. A new mail comes into server1, how does this mail make it to server2. mysql: not "multi master" ready, just redundancy "master->slave", try postgres I don't see that Postgres supports multiple masters either. Circular replication under Mysql may be a possibility if your db traffic isn't too high. apache: behaves in sens of "read only" -> LVS cyrus: moast difficult part (shared storage/CFS,???) -> NAS|SAN+CFS+LVS+?dono? The storage has to reside somewhere. If that site goes down, both servers go down. You either need both servers in the same site with shared storage or figure out how to do a shared nothing backend. kashani -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Server Mirroring...
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Sascha Lucas wrote: > mysql: not "multi master" ready, just redundancy "master->slave", try > postgres Why not try MaxDB? Is not in portage yet, but see this description: MaxDB is a re-branded and enhanced version of SAP DB, SAP AG's open source database. It is a heavy-duty, SAP-certified open source database that offers high availability, scalability and a comprehensive feature set. MaxDB complements the MySQL database server, targeted for large mySAP ERP environments and other applications that require maximum enterprise-level database functionality. It is available for a wide range of platforms, including Linux on several different architectures and Windows. http://freshmeat.net/projects/maxdb - -- Arturo "Buanzo" Busleiman - www.buanzo.com.ar Consultor en Seguridad Informatica / Dominio Digital TV - Da FOSS man! KTP Consultores - info AT ktpconsultores.com.ar Romper un sistema de seguridad los acerca tanto a ser hackers como el encender autos puenteando los convierte en ingenieros automotrices. -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.1 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDd10WAlpOsGhXcE0RAv7hAJ9uFxnycVQqYl16PlJDJBse2Vn6hwCcCDrG g2h2IvwDZlsQp7npXOjpJcA= =Xe7x -END PGP SIGNATURE- -- gentoo-user@gentoo.org mailing list
Re: [gentoo-user] Server Mirroring...
Hi Mal, I run a Apache2 webserver and Postfix as per the virtual mailhost guide... For resilience I would like to have two gentoo boxes doing these tasks for load balancing / redundancy - how can this be achieved? Is there a tool that will allow replication of the config files / mysql stuff to allow the boxes to basically be a cluster ? Thats not so easy to answer. Different solutions exists, each with pros and cons. It also depends heavily on the professional grad your solution should be. You can solve this at different Levels: Hardware, OS, application. Hardware is expensive. OS far from perfect (i.e. openssi, openmosix). Applications must be cluster aware, moast aren't. Do you mean http://www.gentoo.org/doc/en/virt-mail-howto.xml? If so you have to manage a bunch of apps: postfix, mysql, cyrus, apache. Just some keywords: easy with postfix: DNS round robin (solution inside DNS Server, nearly all MTAs are aware of this) mysql: not "multi master" ready, just redundancy "master->slave", try postgres apache: behaves in sens of "read only" -> LVS cyrus: moast difficult part (shared storage/CFS,???) -> NAS|SAN+CFS+LVS+?dono? Cluster/HA is a complex area. Perhaps you want a simple not so perfect solotion? Try periodicaly rsynced standby with manual switch over. Sascha. -- gentoo-user@gentoo.org mailing list
