23 messages in net.sourceforge.lists.courier-users[courier-users] Backup IMAP Servers (...| From | Sent On | Attachments |
|---|---|---|
| Yuan P Li | Feb 18, 2001 3:22 am | |
| Brian Candler | Feb 18, 2001 12:58 pm | |
| Yuan P Li | Feb 18, 2001 7:33 pm | |
| Sam Varshavchik | Feb 18, 2001 7:48 pm | |
| Brian Candler | Feb 19, 2001 3:08 am | |
| David Saez Padros | Feb 19, 2001 7:42 am | |
| David Saez Padros | Feb 19, 2001 7:43 am | |
| Sam Varshavchik | Feb 19, 2001 8:02 am | |
| Adam Sherman | Feb 19, 2001 8:06 am | |
| Tomas Fasth | Feb 19, 2001 8:14 am | |
| David Saez Padros | Feb 19, 2001 8:18 am | |
| Adam Sherman | Feb 19, 2001 8:39 am | |
| Yuan P Li | Feb 19, 2001 12:16 pm | |
| Yuan P Li | Feb 19, 2001 12:58 pm | |
| Yuan P Li | Feb 19, 2001 1:00 pm | |
| Sam Varshavchik | Feb 19, 2001 1:45 pm | |
| Sam Varshavchik | Feb 19, 2001 1:47 pm | |
| Yuan P Li | Feb 19, 2001 1:51 pm | |
| Yuan P Li | Feb 19, 2001 2:07 pm | |
| Sam Varshavchik | Feb 19, 2001 2:17 pm | |
| Yuan P Li | Feb 19, 2001 3:18 pm | |
| Yuan P Li | Feb 19, 2001 3:43 pm | |
| Sam Varshavchik | Feb 19, 2001 4:16 pm |
| Subject: | [courier-users] Backup IMAP Servers (was Re: logging filesystem changes ...) | |
|---|---|---|
| From: | Adam Sherman (ad...@tritus.ca) | |
| Date: | Feb 19, 2001 8:39:37 am | |
| List: | net.sourceforge.lists.courier-users | |
At 5:19 PM +0100 19-02-2001, David Saez Padros wrote:
I think rsync over ssh would do the trick for keeping a backup server syncronized. Maildirs should be rsync safe, and ssh gives you security.
Comments?
The main problem with rsync is:
- If messages are moved between folders by imap users, rsync does not know that it's only necessary to move the message, it will delete the message from the original folder and then send the message to the destination folder (wich is a waste of bandwith)
Very valid point.
- If one message exists on the main server, but not on the backup server, how does rsync know if the message has been deleted by the user on the backup server (this will require to delete the message on the main server) or that the message has been posted on the main server (wich will require to create the message on the backup server) ??
I was narrow mindely thinking that one-way syncronization would suffice. (-:
But I think rsync would be smart enough to figure it out? Also, enabling the use of only one server at a time would help this. (So it wouldn't work for load balansing.) What about naming conflicts?
If pop3ed and imapd could log the changes (which is not so complicated) it will be very easy to do some scripts that could handle in a efficient way the replication ...
Since this is a very interesting topic, let me put out the possibilities:
- rsync - GFS (http://www.globalfilesystem.org) Complicated and expensive - isync (one-way) (http://www.sigpipe.org/isync) - A logging mecanism similar to a SQL "update log" - NAS (http://www.netapp.com) and friends
I do think that the ultimate solution for intra-noc situations would be to make the storage subsystem fault-tolerant. For those wishing to buld geographically distributed systems, the logging idea would be best. Although
A.
-- Adam Sherman President & Technology Architect Tritus CGI +1 (613) 255-5164