Re: Best/Only way to change RBS initial/minextents

"Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in message news:<miLm9.45024$g9.128459_at_newsfeeds.bigpond.com>...
> > I have 25 rollback segments (R01-R25) that are all like this. They
> > reside on the RBS tablespace which is 4 GB (2 2GB datafiles). The
> > db_block_size is 4096.
> >
>
> Oh well, I assume this is Linux, otherwise 4Kb is the wrong block size.

Actually it is HP-UX 11.0. We plan to migrate eventually to Linux, but first up is an upgrade from 7.3.4 to 9i. Either way we will be on HP-UX for at least another year.

> Question 1: How much space do I have for rollback segments? (answer: 60Gb)
> Question 2: How many concurrent transactions do I have to cope with?
> (answer: select * from v$transaction at various times, and pick the
> maximum.... say, 240)
> Question 3: What's 240/4 (ie, 1 segment per 4 concurrent transactions)
> (answer 60)
> Question 4: What's 60Gb divided by 60. (answer 1Gb)
> Question 5: What's 1Gb divided by 6 extents? Er, er, er... damn I wished I
> passed A level Maths!... er, 180K. Or thereabouts.
>
> Therefore: create rollback segement RBS01 storage (initial 180K next 180K
> minextents 6) tablespace RBS;

You're giving me the vibe that the 4 GB I currently have for my RBS tablespace is too small. I can add more datafiles easily on the various partitions. 60 Gb will probably be hard to reach though.

Thanks for the tips. Do recommend doing this various operations with the database down or will just taking the segments offline and doing the re-create be relatively safe in production? I plan to just be safe and take the database down during the wee hours, but I thought I'd ask. Received on Thu Oct 03 2002 - 07:55:52 CDT