Re: Multiple-onlines with shared disk?

> I read the section about multiple residency in the online admin manual, and it > makes clear how to get two completely separate servers going, but what I'd like > to do (because of various contraints) is *share* the data between the > servers. The manual doesn't mention this, only obliquely mentions that one > would want separate chunks. > > Ok, but, suppose I *want* to share the chunks (mainly since we have about > 7Gb of data on 10Gb of disk space; so we can't have two complete copies, even > if we wanted to, which we don't, since the development code needs to see the > changes the production side sees, etc. etc. etc.). So my question is, will > the world END if I share the chunks, rootdbs and all? > > (I called tech-support, by the way, and TSMan's answer was he "thought > so", they can share, but he didn't really seem to quite know what he was > talking about judging from the rest of his answer. I suppose I could pursue > it further there, but I'm much more a fan of the net for genuine answers.) > -- > > Andrew Burt aburt@du.edu Andrew, The world will END - You can't do this. Actually that last statement probably isn't entirely true!!! If both servers only read the database and nothing updated it Informix probably would let you have two servers reading the same server partition. Mind you I can't think of any reason that you would want to do that. The problem comes with updates. As both servers have thier own shared memory area they have thier own locks, dirty pages, etc. You would very quickly totally corrupt your databases as each server overwrote the other servers work. Even if one server only did reads its shared buffers would get of sync from the actual database and your reads would be corrupted. This is a technique used when clustering machines. Each machine has its own server but uses the cluster control to handle locking, etc. Oracle implements this for DEC VAX but I don't know of any Unix boxes that can be clustered like this. Informix does not yet provide cluster support. Perhaps if you described why you want to do this more fully, the net could suggest alternatives to you. If both dev and production need access to the same data why not use one server and restrict permissions on databases and tables for the dev users. As a suggestion to the TSMan if you are asked a question and you don't know the answer. DON'T QUESS admit you don't know and say you will get back to them. Most users don't mind you not knowing as long as you get back to them with the right answer in a reasonable time frame. This guess could have corrupted production databases and lost you a current and many potential customers. Of course if I am wrong then someone on the net will no doubt point it out and I will make an abject apology :-) Cheers - Jim -------------------------------------------------------------------- Name: Jim Gordon Internet: jgordon@ssf-sys.DHL.COM Company: DHL Systems Inc Phone: (415) 358-5911 (Work) Address: 1700 S. Amphlett Blvd. (415) 882-9728 (Home) San Mateo, CA 94402 Fax: (415) 571-6429 --------------------------------------------------------------------