creating new database

Y

yoachan

Member
Hi All!
I'm still confused bout creating new database. such as how many extents vs size per extents. Plus which storage area do I have to choose. (I'm using OE 10.1B). And how can I measure how much do I have to put on -B and -L?

For example if i'm bout to create small database with size about 4 G, and for comparation a mid size database with total size 30G. Any suggestion bout the extents size (and extents quantity), -B, and -L? Some friends said that a smaller extents make greater speed. Is that so?

And if I want to learn more about progress database administration, where can I find the literature?

Big thanks

YoChan.
 
It depends :awink:

You might want to consider going to a training class or having a consultant come in and do some mentoring. These are questions that take some judgment and knowledge about your systems to answer adequately. None the less I'll attempt it from a general perspective:

1) How many extents?

As many as are necessary. It will depend on how many storage areas you define. Personally I generally define one fixed extent and one variable per storage area. I'll define more than one fixed extent for "large" storage areas.

I also define a lot of storage areas. See: Surprising Benefits of Storage Areas for some thoughts on that.

Use OE10 type 2 areas whenever possible.

2) How large should extents be?

That depends somewhat on the capabilities of your OS & HW and any tools that you plan to use to manipulate the extents. Beyond that I try to leave 20% to 50% free space in the fixed extent (see above). On most systems a 2GB maximum extent size is workable and on many systems larger sizes can be used.

Once upon a time UNIX (and DOS) filesystems had performance issues due to indirection. For instance it would take 3 layers of indirection to get to a data blocks in files larger than 64MB. This has not been an issue for a very long time. Large extents are not a performance problem unless you're running some awful dinosaur of an OS with the worst possible ancient filesystem.

3) What should I set -B to?

The setting that reduces IO to the lowest possible value while balancing other needs for RAM on the system. Anything above 100% of database size is a waste. Some people start with 10% of the db size, some with whatever their AP suggests, some people just make something (and some people never budge from their initial setting -- which helps keep guys like me in business...).

4) What should I set -L to?

That's really application dependent. It is the largest number of locks that you will ever need for all users who are simultaneously locking records. You'll have to think about what your application does and go from there. It should not be dependent on db size -- if it is then you have a programming issue that needs to be resolved.
 
Thanks!

Whoa! Thanks mr. Tom. You are always a big help. :lol:
And yes, i think i'm gonna need a training on this matter. will ask my boss' permission to take a class.
Best regards

YoChan
 
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