Re: BaanIV and rollback segments

You might try the below method, while you are trying to get the thing running long enough to accumulate some tx statistics:

(I'm making assumptions/guesses that you've started somewhat low on total rb space, and optimized a bit overmuch for performance. Be prepared to add even more rbs space if "snapshot too old" continues.)

1. create tablespace RBS datafile '/u01/something/rbs1_sidx.dbf' size 1000M;

OK, I've allocated 1Gbyte for rbs space. Now, I will divide it into 10 pieces, 100M each, for 8 rollback segments and 2 pieces left for free space.

2) alter tablespace RBS default storage (initial 2560000 next 2560000 minextents 40 maxextents 128;

3) create rollback segment rb1 storage (minextents 40 maxextents 128 optimal 100000000)

    tablespace rbs;

OK, then add rb2 - rb8 the same as step 3, and alter each to online. Now you have 8 rollback segments sitting at 100 Meg, and each able to grow to about 300 Meg (by extending into the free space and assuming only one at a time is beyond its optimal). Any extended rollback segment will shrink back to 100 Meg when the appropriate commit/rollback happens.

You have to be aware that performance will suffer if the rb segments are consuming cycles by constantly growing and shrinking in a thrashing cycle, so monitor rb growth (although I haven't seen this happen in practice). Also, be sure that these are the only existing rollback segments (as in, be sure to drop the funny little SYSTEM rbs if it is there, plus drop any other old ones).

Roger

Jared Hecker wrote in message <6m34l2$ao2_at_jupiter.planet.net>...
>What is your largest possible transaction and how many transactions will
>be running at once? That is how much space you need to allocate for your
>rollback segments. There is probably a number of tx that require full
>table updates or significant portions thereof and likely as part of a
>complex query you are reading large rows; very few vendors code SQL
>efficiently so I would not be surprised if Baan uses a brute-force
>approach at times.
>
>hth -
>
>Regards,
>jh
>
>Han Brinkman (hbrinkman_at_profuse.nl) wrote:
>: We are running an Oracle 7.3.3 database with BaanIV b2. The db is about
9Gb
>: large. Rollback segments were 20 * 30Mb which have been changed last week
to
>: 10 * 60Mb. Still we sometimes get the 1555 error. Is there someone who
can
>: tell me the size of their rollback segments in combination with Baan? As
you
>: probably know within Baan it's not possible to specifiy specific rollback
>: segments which it has to use.
>
>: Thanks in advance,
>: Han Brinkman
>
>
>
>--
>Jared Hecker | HWA Inc. - Oracle architecture and Administration
>jared_at_hwai.com | ** serving NYC and New Jersey **
Received on Mon Jun 15 1998 - 16:16:13 CDT