Re: Replication and HDR

In article <38552dce_3@news.delphiauto.net>, "Michael K Anderson" <michael.anderson@eds.com> wrote: > On Tue, 30 Nov 1999, Greg wrote: > > <gresmi@yahoo.com> wrote in message news:821u53$dir$1@nnrp1.deja.com... > > We are looking at implementing replication between 2 of our servers, a > > primary in Ft. Lauderdale and the secondary in L.A., possibly using > > Informix's High Availability Data Replication (HDR) tool. > > > > Our questions are these: > > 1. The Informix manuals state that the hardware and OS must be identical > > for the primary and secondary server. How much flexibility is there > > on this? The Ft. Lauderdale machine is an IBM RS/6000 J30 and the L.A. > > machine is an IBM RS/6000 F30. Our Ft. Lauderdale machine > > has 4 CPU's and the L.A. machine has 1. We have AIX 4.3.2 running on our > > primary machine in Ft. Lauderdale and AIX 4.3.1 running on > > the secondary machine in L.A. Our Ft. Lauderdale machine has 512MB of > > memory and the L.A. machine has 256MB. It's been recommended that we > > sync the AIX versions, but I haven't gotten a definitive answer on the > > hardware. Do any of these situations require changes? It's not a great > > undertaking to upgrade the L.A. machine to 4.3.2. > > > > 2. We've found some comments on the web regarding the Informix version > > to use for replication. Most of those of a positive nature recommend > > using v7.31uc4, or at least v7.31uc3. We're leaning toward syncing them > > at v7.31uc4, charmed with the notion that the latest should be the > > greatest. > > > > 3. Can HDR be implemented using buffered logging instead of unbuffered > > logging? The production databases on both these machines currently use > > buffered logging? Are there disadvantages to doing that? > > > > 4. If we're configuring for a primary/secondary scenario with the > > secondary to serve as a hot backup, what would be the preferred method > > of transfer? Asynchronous or synchronous? > > > > 5. Also, the dbspaces, logical logs, physical log, and config files are > > virtually the same, needing only some minor tweeking to sync them up. > > > > Does HDR sound like a decent solution for our requirements? We need a > > hot backup server that can stand in and handle production processes in > > the case of failure of the primary server in Ft. Lauderdale, with the > > least amount of impact to the primary production system. No writes are > > to take place on the secondary, unless the primary were to fail. The > > machines can already talk to each other through the network. > > > > Thanks Much, > > Greg > > > > > > Sent via Deja.com http://www.deja.com/ > > Before you buy. > > We are currently running HADR with IDS 7.23 on HP-UX with no problems. > 1) According to everything I have read, the primary and secondary servers > have to be identical in almost every way - physical hardware, operating > system and IDS version. If the sole purpose of the secondary server is > a back-up, you could get by with one CPU. If you have to fail-over to > the secondary. There could be a significant degradation in performance > going from a 4 CPU machine to a 1 CPU machine. > 2) Your best bet is to go with the 7.31 uc4. > 3) HADR can be implemented using buffered logging. This could actually > could actually contribute to a decrease in processing overhead on the > primary server. > 4) We are using synchronous transfer mode because it is the most secure. > We are also using unbufferd logging. > 5) The dbspaces, logical and physical logs should be the same. You should > use a copy of the config file from the primary, then make necessary > changes. > > The network must be stable and robust. The network must be able to handle > the communication between the two servers as quickly and reliably as > possible. > > Carlton Doe's "INFORMIX-Online Dynamic Server Handbook" is an excellent > resource for configuring HADR. > > Michael, Thanks for the input. I will try to get my hands on Carlton's book as soon as I can. Greg Sent via Deja.com http://www.deja.com/ Before you buy.