Hi Guys,

I have a question on rollback segments.I hope so many of you are good enough to clarify this.Please give me a detail reply.I read some books but unfortunately I think i am not getting the core concept.

I have a production database 24*7 (Oracle 734 on Windows NT 4.0 Patch 6a).I created another database on the same server whoose structure is as same as production(empty database) for some purposes.In production database i have 10 rbs EACH OF 1M AND ROLLBACK TABLESPACE IS 30M.But in the empty database :

I created a tablespace :

create tablespace rollback
datafile '/rollback' size 500m autoextend on next 1m
default storage (initial 160k,next 160k,minextents 1,maxextents unlimited,pctincrease 50);

I created a rollback segment

create rollback segment rbs2
tablespace rollback
storage(initial 30m,next 30m,minextents 2,maxextents 121);

1.When i see from OEM the used space in rollback tablespace is 60m .Is it because of 2 minextents each of 30m?

2.Is it good enough to cretae a one big rollback segment instead of few smaller ones?

3.If not ,how many small RBS i have to create with what parameters cosidering my rollback tablespace.

Thanks in advance
Ravi