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13 messages in net.sourceforge.lists.courier-users[courier-users] RES: RES: Courier B...| From | Sent On | Attachments |
|---|---|---|
| Sam Varshavchik | Nov 24, 2007 7:15 am | |
| Ronie Gilberto Henrich | Nov 24, 2007 9:24 am | |
| Jay Lee | Nov 24, 2007 3:39 pm | |
| Jérôme Blion | Nov 24, 2007 7:11 pm | |
| Ronie Gilberto Henrich | Nov 25, 2007 9:36 am | |
| Jay Lee | Nov 25, 2007 10:37 am | |
| gor...@bobich.net | Nov 26, 2007 2:25 am | |
| Ronie Gilberto Henrich | Nov 26, 2007 7:12 am | |
| gor...@bobich.net | Nov 26, 2007 7:28 am | |
| Jay Lee | Nov 26, 2007 8:18 am | |
| gor...@bobich.net | Nov 26, 2007 8:27 am | |
| Ronie Gilberto Henrich | Nov 26, 2007 10:23 am | |
| gor...@bobich.net | Nov 27, 2007 1:40 am |
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| Subject: | [courier-users] RES: RES: Courier Backup / replication point | Actions... |
|---|---|---|
| From: | Ronie Gilberto Henrich (ron...@ronie.com.br) | |
| Date: | Nov 26, 2007 7:12:44 am | |
| List: | net.sourceforge.lists.courier-users | |
Hi Jay, Hi Gordan,
I will explain better our today's setup, I cannot see/understand how your solution could fit/work in our environment: 2 "external" servers: they are firewall, LVS and load balancing; 2 "internal" servers: they are the courier servers;
* The 2 "internal" servers replicates data between each other using unison; * We don't have a SAN and/or NAS, and we don't want use a SAN/NAS/storage, here are the reasons: 1) Price (it is a very expensive solution); 2) To have a SAN/NAS/storage "SPOF free" we have to duplicate it, having 2 storages, 2 SAN switches, and at least 2 network cards exclusively for the SAN/NAS/storage solution; 3) It means an even more expensive solution; 4) Also we cannot forget that using more equipment, means more energy consuption; 5) Oh, not to forget we need more room for the SAN/NAS/storage solution comparing to a simple "service replication" solution.
My idea is to optimize the use of resources. If we don't need to replicate everything, why don't replicate just what we need?
Jay, about the NFS solution, how does it work regarding syncronism? I mean, will the files in the 2 servers be always the same? Example, courier saves a file on server 1, at the same time will that file be updated in server 2?
My idea was to contribute with the courier project including a feature where will allow it to save the files in 1 or more backup/replication points. The idea was not to do everything inside courier, I was thinking to include an option where courier could generate a kind of "redo log" (similar to oracle) and an extra package would read those "redo log" files and do that on the replication servers. With this "redo log" idea, it will be always possible to have the servers syncronized, even if we put a server in maintenance mode, after coming back to online mode, it will run the "redo log" files to be in syncro with the other servers again.
I don't want to re-invent the wheel. I am just suggesting to add an extra truck (server) and distribute the weight between them. Then in the case one truck fails, the drivers have just to attach the brocken truck's load to the other truck and let it continues the journey.
Best regards,
Ronie
-----Mensagem original----- De: gor...@bobich.net [mailto:gor...@bobich.net] Enviada em: segunda-feira, 26 de novembro de 2007 05:26 AM Para: Ronie Gilberto Henrich Cc: Jérôme Blion; Jay Lee; cour...@lists.sourceforge.net; cour...@lists.sourceforge.net Assunto: Re: [courier-users] RES: Courier Backup / replication point
This sounds very much like a re-invention of a wheel. If you need high-availability and load sharing on your mail system, then cluster the servers properly and set up a GFS file system on top of a SAN or if you don't have a SAN, on top of a DRDB. I have recently deployed just such a system. I cannot see any advantage to lifting this functionality up to the application level when a more generic solution already exists.
If you want to also share the root file system, look at the "Open Shared Root" project. If you don't want to do it based on SAN/DRDB and GFS, you can do it all based on NAS/NFS, but that still leaves you a single point of failure (NAS appliance, unless that is mirrored using something like NBD (cold spare) or DRDB (hot spare)).
Gordan
On Sun, 25 Nov 2007, Ronie Gilberto Henrich wrote:
-----Mensagem original----- De: jl...@gtest.pbu.edu [mailto:jl...@gtest.pbu.edu]Em nome de Jay Lee Enviada em: domingo, 25 de novembro de 2007 01:38 PM Para: ron...@ronie.com.br Cc: Jérôme Blion; cour...@lists.sourceforge.net; cour...@lists.sourceforge.net Assunto: Re: [courier-users] Courier Backup / replication point
There is no need to replicate the entire filesystem, just your data. So have a RAID1 root filesystem in each of your two servers and then have them NFS mount the shared Maildirs.
-- Jay Lee Network / Systems Administrator Information Technology Dept. Philadelphia Biblical University
Hi Jérôme, Hi Jay,
The disadvantages in using something at the filesystem/block is specially regarding load balancing. We have two servers, with different IP addresses inside our network, where courier is running. At the front, we have the firewalls and LVS doing a load balancing. They will redirect to the active courier server. So, if we replicate at the filesystem/block layers, we have to take out several files from the replication proccess, because the different IP addresses, different server names, and so on.
As a solution for that situation, I think that a "replication point" feature in courier will be a nice solution.
We have a software develop team, so we can do that contribution to the courier project.
Maybe we could improve this idea...
Best regards,
Ronie
-----Mensagem original----- De: Jérôme Blion [mailto:jero...@free.fr] Enviada em: sábado, 24 de novembro de 2007 10:12 PM Para: Jay Lee Cc: ron...@ronie.com.br; cour...@lists.sourceforge.net; cour...@lists.sourceforge.net Assunto: Re: [courier-users] Courier Backup / replication point
Jay Lee a écrit : Sounds to me like something that should be (and has been) configured at the filesystem/block layers rather than at the Courier application layer. Take a look at projects like RedHat's GFS or Sun's ZFS. I don't know much about NetApps either but I know they do NFS very well (which Courier supports very well) and I'm pretty sure they can be configured redundantly.
Jay
On 11/24/07, Ronie Gilberto Henrich <ron...@ronie.com.br> wrote:
Is it any feature in courier that allows me to inform backup storage paths?
Today I use unison to maintain a replica of our email files, configurations, ..., in a second server to use as a fast recovery backup solution. The problem is that unison uses a lot of resources and IO_WAIT is always very high.
So, I was wondering if it is any feature to inform backup storage paths for courier to save all its files always into two different paths. Does something like this exist?
If it does not exist, don't you think it is a interesting feature to be implemented?
Thanks and regards,
Ronie
Hi,
If we work with a filer, an easier way to proceed would be to affect LUNS/filesystems to the "backup" server. This way, you don't have to copy anything... The rollback on the master server just follows the same process. After that, you have to secure your filer. (snapshot and so on)
HTH. Jerome Blion.