Re: Data Replication
Hi,
It looks like I made the assumption that you are using 'auto' switchover.
If you are using Manual you need to turn the secondary to standard manually.
Sometimes, for unknown reasons, it fails. You restore the secondary and
repeat the above steps it works fine. ( I could not figure out why it
happens). I tried this and once or twice it happened. After that it never
happened again. ( Who knows it may happen again).
Thanks & Regards,
Srinivas Reddy
On Mon, 9 Sep 1996, Srinivas Reddy wrote:
} Hi,
}
} The very first thing is it is not DHR. It should be HDR
} (High-availability Data Replication). (assuming it is a typo).
}
} We are using HDR still in development and test environment.
} H/W -- HP K400s with HP-UX 10.10
} Informix --- OL 7.20
}
} 1. When primary goes down (or you bring it down using 'onmode -ky') the
} secondary automatically turns into standard (Read-Only (Sec) to
} On-Line ) and it allows the write operations. You do not have to
} give the command 'onmode -d standard'.
}
} When primary is down secondary (turned standard) will allow write
} operations on it. Now you bring the primary up and see what happens. It
} automatically applies the transactions, which you performed on secondary
} when primary is down, from logs of secondary. It does not really take
} much time. Now the questions arises 'What if I backed up the logical logs ?'
} Will it do the re-synch automatically ?
}
} The answer is : 1. you backed up the logical logs but not freed then it
} will read from the disk and applies.
} 2. you backed up the L.Ls and and freed them from the disk then while you
} bring up the primary it prompts for L.L tapes and it reads from the tapes
} and applies.
}
} **** Some where in these mails (not yours) I read somebody suggesting to
} give the command to first turn the secondary into 'Primary' and then to
} standard which is not required (not correct). Depending on your requirement
} you can use either 'Retain type' or 'Reverse type'.
}
} As I mentioned in the beginning I am using 7.20 UC2 on HP K400 with HP-UX
} 10.10 I do not have any problems. ( I still have a problem, that is, I can
} not run any commands like 'dbschema', 'dbexport' on secondary while HDR
} is on, talking to Informix about this).
}
} Try in the following way, if you still have the problems it may related
} to 7.11 problem.
}
} 1. Make sure that both the engines are in replication pair and working fine.
}
} -- perform few operations on Primary ( any way you can not perform any
} wirtes on seconday at this stage) and see how they are replicated.
}
} 2. Bring the Primary to offline by giving the command 'onmode -ky'
}
} 3. Observe that the secondary will automatically turns into 'online' mode
} (i.e. standard) and allows write operations. IF THIS IS NOT HAPPENING
} 7.11 MAY HAVE SOME PROBLEM.
}
} -- now perform few write operations on secondary ( which is standard now)
}
} 4. Bring the Primary to online by giving 'oninit'
} ( you do not have to do anything on secondary, it automatically
} becomes 'Read-Only (Sec)' )
}
} Observe what happens. It should come up and should apply the
} transactions from secondary.
}
} *** PLEASE READ THE THE MESSAGE LOG ALL THE TIMES.
}
} 5. Other way is also true. (i.e bring the secondary down and repeat these)
} But you will notice the Primary will still remain in 'On-Line (Prim)'.
}
} Whether you use synch or asynch the above things work.
}
} Hope this helps you. If you still have problems with 7.11 ver, the best
} thing is to call Informix tech support they will walk you thru the steps and
} suggest the solution. ( hopefully )
}
} If you need some more info please let me know.
}
} Thanks & Regards,
} Srinivas Reddy
}
}
} On Fri, 23 Aug 1996, pjhaveri wrote:
}
} > Hi,
} > Sorry for late reply. I am using 7.11UC2. We are testing replication.
} > It is DHR. And asysnchronous mode.
} >
} > - I was trying to test if primary goes down, whether I can use seconadry as a
} > standard server and when primary is up, whether I can change seconadry-which
} > was standard to seconadry.
} >
} > So when REPLICATION WAS WORKING, I shutdown PRIMARY, made seconadry as
} > standard server.
} > using onmode -d standard command.And :-))
} >
} > It could not change mode to standard mode.
} >
} > Probs : Seconadry could not change mode to ONLINE fm RECOVERY MODE !!!
} >
} > I tried to take it to offline mode and then tried to bring it up, It did not
} > work. It remained in the recovery mode.
} >
} > On the other side when we tried to bring up primary, we could not. Following
} > is the msg from msg log file.
} > ***********************************************************************
} > 18:36:09 DR: DRAUTO is 0 (Off)
} >
} > 18:36:15 INFORMIX-OnLine Initialized -- Shared Memory Initialized.
} >
} > 18:36:15 DR: Trying to connect to secondary server ...
} >
} > 18:36:16 DR: Primary server connected
} >
} > 18:36:17 DR: Server type incompatible
} >
} > 18:36:17 rshdr.c, line 3344, thread 23, proc id 3232, DR: Server type
} > incompati
} > ble.
} >
} > 18:36:17 PANIC: Attempting to bring system down
} > ****************************************************************************
} >
} >
} >
} >
} >
} > I tried
} >
} > ------------- Begin Original Message -------------
} > From: attmail!internet!rmy.emory.edu!informix-list-owner (Juan R. Guzman)
} > Date: Mon Aug 12 19:20:29 +0000 1996
} > Subject: Re: Data Replication
} > To: attmail!internet!rmy.emory.edu!informix-list
} > Content-Type: text
} > Content-Length: 741
} >
} > pjhaveri wrote:
} > >
} > > Hi,
} > >
} > > We are trying Replication between 2 cities. I wanted some information about
} > > this. Anyone is using replication, what are the problems you have faced.
} > And> what type synchronous or asynchronous mode is preferable ?
} > >
} > > your input would be greatly appreciated!
} > >
} > > Thanks and Regards,
} > > Pritirj
} >
} > You didn't say which on-line your using or which tpe of DR (DHR or
} > CDR). I have 7.11UC1 and it has a bug. When you try to bring up the
} > secondary (from scheduled downtie or not) it won't find the checkpoint
} > in the log log and so it stays in recovery mode.
} >
} > I would be very interested in hearing your feedback on how it goes
} > because I'm thinkg of doing the same (DR is local now).
} >
} > thanks,
} >
}