Re: Data Replication questions
Dear Dhanesh Kottile Veedu wrote:, Thanks a lot for your feedback. I have the following additional points for discussion: If we use HDR (provided we can have enough hard disk chunks - currently the customer is using cooked files ) then do we need 5*128 MB of RAM on the replicating machine? Another issue of great concern is, if a server fails, then do we get the same performance from the replicating machine, given that it acts now as one server and a replicating machine for the other 4 servers. Do we anticipate a network meltdown? The customer is a Hospital with huge amount of non-stop transactions Is it better to provide dedicated ethernet cards and cables between the 5 servers and the backup one. If we go with ER do you expect that we are immune from the above possible problems? or do we need to upgrade the backup-server (at least the RAM size)? One last point, can we use both mirroring and replications without getting into steep performance degradation problems. Best regards, Amgad Al-Sisi Dhanesh Kottile Veedu wrote: > If you are planning to use HDR, you need to configure the target > (secondary ) server with the same configuration ( most of the parameters ) > as the primary server. > Since you have five different instances (SERVERS), you cannot use one > instance where you can replicate all the five servers. But still you can > configure five instances on the target machine for replicating all the five > servers. > Since in HDR, the logical logs of the primary servers need to be send to the > Secondary servers, which creates network traffic. You have two options when > u replicate -- Synchronous and aysnchronous. > Since you have only 256 MB of RAM, it may result in swapping and hence a > degrading of perrformance in the target (secondary server), if you configure > five instances. > Any questions , conerns appreciated > Dhanesh > -----Original Message----- > From: amgad@starnet.com.eg <amgad@starnet.com.eg> > Newsgroups: comp.databases.informix > Date: Sunday, May 23, 1999 1:38 PM > Subject: Data Replication questions > > >Dear colleauges, > > > >Our customer has the following setup: > > > >5 ICL TeamServer machines running DRS/NX unix and Informix-Online > >version 7.22.UC2. Each server is a uni-processor > >machine with 128MB of RAM, where a separate database resides. For > >example, on the first server there is the personal > >database, on the second server there is the accounting database, and so > >on. The application is written in 4GL and use > >distributed transactions on 5 databases running on the LAN connected 5 > >DRS/NX servers. > > > >For fault tolerance, the customer have another machine (number 6) which > >is ICL superserver dual processors with > >256MB of RAM. The customer wishes to use replication to obtain high > >availability, as this site is 24x7 working place. > >The customer wants to know if the superserver with the current > >configuration can be used to work as the replica machine > >for all the five servers or not. and whether it is better to start one > >Informix-Online instance with 5 databases on the > >superserver, where each database is the replica of the other one on the > >TeamServer (e.g. personal on machine #1, > >accounting on machine #2, ..etc.). Or, it is neccessary to start 5 > >instances of Informix-Online where each instance > >handles one database. > > > >If the current configuration is not enough, what would be the desirable > >configuration for the server hardware. > >The current no of users is around 100 users, and the site operates 24 > >hours a day, seven days a week, and > >wants to use replication as a mechanism to avoid service outage. > > > >The current LAN configuration is all of the Servers (5 + 1) are > >connected on a coaxial 10MBPS ethernet network. > >The current system performance is good for the user, but when > >replication starts, is it going to degrade because > >of the network bandwidth or the current server condifuration? Please, > >take this issue into consideration when > >evaluating the available options. > > > >This is an urgent case and I will really appreciate your earliest > >response. > > > >Regards, > > > >Amgad Al-Sisi > > > > > > > > > >--== Sent via Deja.com http://www.deja.com/ ==-- > >---Share what you know. Learn what you don't.---