Re: how to update database by only applying logical logs

hiro3@fra.allnet.ne.jp wrote: > You are right. I should have said more clearly what I want to do. > As you imagined, I am tried to build a 2nd server on a different machine. > But I am exploring possibility without using the built-in > replication facilities but with storage-based replication solution using EMC > Symmetrix and so on. EMC Symmetrix offers the solution without using any > resources on the machine such as a memory and CPU so that the Symmetrix > synchronizes volumes in itself with ones in another symmetrix. So I am > wondering if there is any way of applying logs on the solution for Informix. > I know there is for Oracle. Your scenario is clear enough now. There are several issues to worry about. The first is that I'm not an expert on Informix replication strategies, so what follows is very much TTBOMK - to the best of my knowledge - and other people who know more about the nitty-gritty details may well have to step in and correct mis-statements I make. You were warned! 1. Is the second server going to be anything other than a read-only system? If yes, then you really need to be using the Informix replication mechanisms to resolve conflicts. 2. Even if it is going to be read-only, there are no ways to tell the Informix server running against the second copy of the data that it can't modify the disk, but the disk data might change behind its back as the EMC Symmetrix system copies material around. 3. So, if this is other than a one-off copying exercise, I think you are going to find it difficult to do except with the Informix-supplied replication which can keep the second server in the hot standby mode. (And this is where I decided to write the TTBOMK disclaimer above). 4. As a one-off copying exercise, I suspect EMC Symmetrix would handle the job for you without troubling the server at all; the only hard part might be telling when the two servers were fully in sync. ...Anybody else want to chip in with anything useful? Help...!!! > "Jonathan Leffler" <jleffler@informix.com> wrote: > > hiro3@fra.allnet.ne.jp wrote: > > > I need to know how to update database by only applying logical logs. > > > > Why? Why do you want to do it? > > > > > If you can suggest or advise anything, that would be appreciated. > > > > I assume "Don't" is not acceptable advice? :-) > > > > You need to define what you are trying to do a lot more clearly. Is > > there one database server or two or more in use? Are you trying to > > replicate the changes in Server1 on Server2 (Server3, ...)? Or are you > > trying to recover Server1 from the log files of Server1, avoiding the > > overhead of doing a Level 0 restore? Or what? > > > > If you're trying to avoid the restore, I think you're on a hiding to > > nothing. > > > > If you're trying to do replication, what's wrong with the built-in > > replication facilities (some of which are at least partially log based)? -- Yours, Jonathan Leffler (Jonathan.Leffler@Informix.com) #include <disclaimer.h> Guardian of DBD::Informix v1.00.PC1 -- http://www.perl.com/CPAN "I don't suffer from insanity; I enjoy every minute of it!"