"Manual" Mirror?

in Message-Id: <2shfoa$3it@raffles.technet.sg> scornd3@solomon.technet.sg (SCO R and D) writes: > Can anyone offer some ideas on the following. > > I will have two servers A and B. A is online committing transactions. > B is offline. At some point, a full backup of A's db will be effected to > be duplicated into B. This is done, probably, with a tape. B is then > relocated to a remote site (up to 50km away). B is then started up. Before B > can get online the "new" transactions in A (after the backup to B) must > be transferred to B. B is linked to A via a unreliable wireless link. > > My current thinking. > To detect the changes after the backup. Extract this into ascii, compressed > and emailed to B for further restoration. While this is going on, A is still > effecting changes. At some designated time, B will take over from A but > it is forseeable that in the background some changes at A are still being > pumped to B. But this is minimal and should not severely impact B going > online. > > Without incurring overheads of logging the transations in my application, is > there some log file/table kept by Informix that will allow me to implement > the above. > > Or is there some really simple method, I've overlooked. Any inputs will > be welcomed. Huh? Exactly what is it that you're trying to do? Will B take over from A, even over an unreliable wireless link? Will A go away? Do you want both machines to run in synch? Is there an operational requirement for how much data you can afford to lose if A goes down (how in-synch must they be?) Some tentative answers: You can archive at different levels (0,1,2) and send the archives to the B machine periodically. At shorter intervals you can copy, compress, and send the current log to the B machine (it contains all transactions since the last archive.) If your transactions are "batch" style files (some of ours are) then you can easily copy the files for processing at both machines, and not rely on the Informix archives at all. You could use cooked files, and NFS mount a mirror disk remotely (though not over an unreliable link.) See the Informix OnLine (or SE, whichever) Administrator's Guide v5.0 chapter 4 (Data Consistency, Recovery, and Migration) for a clue how the archive/log process works. Good luck, __________________________________________________________________ | Clem Akins Standard Disclaimers Apply | | Reynolds Metals Co. "Climb High, Cave Deep!" | | Muscle Shoals, Alabama USA cwakins@leia.rmc.com | |________________________________________________________________|