Yes - you have it correct. > It would seem that Server#1 never runs 4D Backup, because any restoration > would be done using Server#2. Nevertheless, if Server#1 started up and > somehow choked, a "normal" behavior would be to restore from backup and > integrate the log file. Since this behavior would be turned off, what is > the procedure you use if Server #1 won't start? Do you copy the mirror on > Server #2 to Server#1?
- Yes, you'll never back up server #1 and you'll disable the automatic restore after crash feature. - If server 1 crashes and you bring it up, 4D analyzes its current journal file and if any operations are not integrated in the data file, they are automatically integrated. - If server 1 won't start (i.e. damage detected or the journal won't integrate for some reason), you'll need a recovery procedure. > How do you handle the timing, so that [Server#2] knows that the file > transfer is complete and it is OK to integrate the log file? Does > [Server#1] somehow send a 'I'm Done' message to [Server#2] in your > implementation? You could send a message from #1 to #2. We just use an old-fashioned lock file. Write the lock file, copy the journal file, then delete the lock file. You could also copy the file with a .tmp extension, and when done rename .tmp to .journal (and your code would filter out .tmp files to prevent them from integrating). In our server, we ship a new journal file every 30 seconds. They are numbered sequentially, so you can sort them by file name and integrate a batch in the correct order. > What do you do if [Server#1] dies to now point users to [Server#2], > assuming the Server application is a built application so that the server > address and port number are built into the (built) 4D Client? Change the DNS entry, or manually copy the data file from #2 back to #1. We do the latter. It happens so infrequently that 10 minutes to recover isn't a big deal. Jeff ********************************************************************** 4D Internet Users Group (4D iNUG) FAQ: http://lists.4d.com/faqnug.html Archive: http://lists.4d.com/archives.html Options: http://lists.4d.com/mailman/options/4d_tech Unsub: mailto:[email protected] **********************************************************************
