RSYNC for Incremental Replication

[Yaboto]

Hi,


I want to be able to be updating my Oracle Dabase from the main site to the DR site using RSYNC with my RHEL5.
Does anybody know any better method to suggest to me ?

What is the best format I can use for that purpose ?

Best Regards,

[TwoProc]

Are you asking how to create a standby database, or a data guardian database copy of production, or are you simply asking how to use rsync to copy a set of files to another site? What files? All files, or just the archive logs for processing?

Of course, you could shut down the database once a day and copy all of the files, but that's not going to keep you current.

You could also, one at a time, take each tablespace, put it into hotbackup mode. Then while it's in hotbackup mode copy ALL of the related files to THAT tablespace to the other server (rsync, scp, whatever). Take that tablespace out of hot backup mode, and then do the next, repeating as necessary until all tablespaces are copied to the other site.

The problem with the last suggestion is the huge amount of time necessary to keep the tablespaces in hot backup mode. The tablespace is still usable, the big downside is that all changes to the tablespace are handled block-wide, not row-wide - meaning that your archive log space is filling rapidly if you're busy.

Lastly, if you're thinking you're going to use rsync against the running Oracle databases while it's up; well, it's not gonna work unless you put that whole system in hotbackup mode, and then do a recovery when you really need it. You could go with partial hotbackups per area, if you're lucky enough that you're tablespaces are split and organized by directory area that you're rsyncing. The problem is, that they are probably not, and you would have had to been thinking about the limitations of that process while organizing the files and tablespaces, and directories. You could of course, to that very thing now, but now you're organizing for rsync backups, not for performance. And, of course, that all depends on your storage system, and how well it would handle an rsync-hotback friendly setup; and if it's big and bad enough, maybe it can!

The answer, unfortunately, like most things is: it depends.

Personally, I think you should look at Oracle Data Guardian product, or at Oracle's standby databases to get this done for you as a possible alternative.

The other would be using your storage hardware vendors tools for asynchronous replication to another site. This is probably your most expensive, yet best solution out there.

[dirk dierickx]

i wouldn't use rsync for that, it is not designed to create DR copies of DB's. besides, your DR copy will be outdated since rsync doesn't do CDP.

either look for a solution provided by the DB (mysql for example has such features build-in, i'm guessing for oracle it's an add-on with a price). or if you are on a SAN you could use replication features of your disk array.

products like symantec/veritas volume manager also allow volume replication between hosts.