Keeping a backup server synced with live server

[Q-Mike]

Hi all,

I am using Zimbra Network Edition 5.04 on a single server with Ubuntu 6.06. I would like to setup a backup server in an other location to implement disaster recovery. I looked at cluster setup, but it requires a shared SAN which I don't have, especially in different locations !

My idea is to have a backup server that I would keep in sync with the live platform by doing incr backup every hours and transferring those to the backup server and replaying them. In case of crash, I would just need to change DNS entries, and the backup server would become live.

For now, I have been able to set up 2 platforms, doing a full backup a week and inc backups every hours and rsyncing the inc backups to the backup server. I have also restored the full backup on the backup server, and been able to replay the inc backups. However, the zmrestore command always restores the account from a full backup then replays the redologs from the inc backups.

Is there a way to only replay the redologs that have not been applied instead of starting with to restore the full backup ? I would then be able to to keep the servers in sync and in case of failure of the live server (complete crash, or network problem, or whatever...), setting the backup server as the main server will only take the time of DNS TTLs, instead of the time of a full restore...

This would also be very useful to lower the downtime when changing for a more powerful server

Of course, any better solution is welcome

[uxbod]

Welcome to the forums

I will need to research this a bit first. Just thought I would welcome you in the meantime though

[DMRDave]

Q-Mike,

I'm looking at having a setup very similar to yours. If possible, would you be kind enough to share (or at least provide a few pointers) how you've come to the point where you currently are? Thank you in advance. I'll be watching this post with interest.

[Q-Mike]

Yes of, course ! I should Have mentioned my setup is quite similar to this thread : How to: cold standby server (no cluster)


Basically, I have 2 servers installed exactly the same way :

• Ubuntu 6.06
• install of zimbra network edition (no proxy, no archiving, zimbra mobile), 50 users.
• some customisation like apache front end in reverse proxy mode (Ubuntu version)
• rsync installed on both servers

On the live server, I do an incremental backup every hour and and full once a week.
On the cold backup server I have rsynced the whole backup directory (ssh keys for auth, I do this as root for now, but using zimbra user should be sufficient) :

rsync -aHzv --rsh=ssh livemail:/home/zimbra/backup/ /home/livemail/zimbrabackup/

This took a bit more than 2 hours.


On the cold backup server, every hour I would like to do :

• Rsync of inc backups only :
  

  rsync -aHzv --rsh=ssh livemail:/home/zimbra/backup/sessions/incr-* /home/livemail/zimbrabackup/sessions/

  This runs really fast : < 1 minute
• restore to the state of live server :
  

  zmrestore -t /home/livemail/zimbrabackup -br -a all -c --ignoreRedoErrors

  This takes about 2 hours, but it will keep getting worse since there will be more and more mail in the mailboxes.

I would like to reduce time of restore, because if I have done the full restore once, I then only need to play the redologs to get into the same state as the live server.
I know this can lead in some problems : all system mails received on the backup server might break the redolog sequence and cause some problems (maybe a flag like --ignoreRedoErrors would help by replaying the redologs even if some event has occurred between 2 plays). Or maybe I will have to put the domain in Maintenance mode and in case of disaster, part of the procedure will be to put the domain in Active mode... I am sure there is a solution

This is about where I am up to... Hope it helps

Michael

PS :
I also want to make the zmbackup (incremental) on the live server happen just before rsync from the backup server. This can easily be achieved using rsync daemon and "pre-xfer exec" option. In that way, all the replication process is controlled by the cold backup server.

[alexismedina]

Maybe you can try to use zimbra with drbd (for sync data) and hearbeat (for ip change)

check this

[SOLVED] Zimbra on DRBD

[DMRDave]

Q-Mike,

Just wanted to say thank you very much for the response. We are moving to the NE version of Zimbra in the next few weeks, and this will help me huge. We've are currently 4.5.9 FOSS moving to new hardware and i'll be upgrading to NE 5.0.4. 32 bit Ubuntu 6.06 on both servers. Thanks again.