What is an instance?

The books I have read do not help me understand what an instance is. If I have one rootdbs, and 2 dbspaces with data, is there 1 instance? Also, if I have a live database in 1 dbspace and a train database in another dbspase, will ontape archive them both? If so, will I be able to restore in the future to only 1 database, say train, and not overwrite live?

an instance is an entirely separate "instance" (for lack of a better word) of the database engine. A single database can have many dbspaces. Typically, I have seen separate instances used to separate a development or training database from a production database, but if they are set up with the same configuration (same chunks, dbspaces, and all that good DBA stuff I don't know anything about), you can restore 1 to the other. Ontape will archive them both, but I believe you'll have to run it separately for each instance, why not just send the training one to /nev/dull? Anyway, standard disclaimers apply. I am not a DBA, nor have I read any books ;-) Honda75 wrote: > The books I have read do not help me understand what an instance is. If I have > one rootdbs, and 2 dbspaces with data, is there 1 instance? > > Also, if I have a live database in 1 dbspace and a train database in another > dbspase, will ontape archive them both? If so, will I be able to restore in the > future to only 1 database, say train, and not overwrite live?

The best way I think you can define an 'instance'. Each instance has to have it's own unique SERVERNUM and unique INFORMIXSERVER...you can have multiple instances running from the same install of informix. -brian On Fri, 21 Jan 2000 22:59:26 -0600, Danny Wright <danwright@bigfooot.com> wrote: >an instance is an entirely separate "instance" (for lack of a better word) of the >database engine. > >A single database can have many dbspaces. > >Typically, I have seen separate instances used to separate a development or >training database from a production database, but if they are set up with the same >configuration (same chunks, dbspaces, and all that good DBA stuff I don't know >anything about), you can restore 1 to the other. > >Ontape will archive them both, but I believe you'll have to run it separately for >each instance, why not just send the training one to /nev/dull? > >Anyway, standard disclaimers apply. I am not a DBA, nor have I read any books ;-) > >Honda75 wrote: > >> The books I have read do not help me understand what an instance is. If I have >> one rootdbs, and 2 dbspaces with data, is there 1 instance? >> >> Also, if I have a live database in 1 dbspace and a train database in another >> dbspase, will ontape archive them both? If so, will I be able to restore in the >> future to only 1 database, say train, and not overwrite live? >