DB Extent Size

[ron]

Does anyone have some words of wisdom regarding extent size?

We run Progress 9.1D07 on Solaris 8 (going to Solaris 9 within the next month). We use striped discs (RAID 1+0).

Our DB is 155GB and we have divided it into 9 Areas. Some smallish Areas contain data with a very low level of update; some Areas contain just one or two very large and volatile tables; others are "mixed".

At present we have large files enabled both in Solaris and in Progress.

Our extents are all set to 2GB. This leads to a lot of wasted space because we have 9 Areas.

I can find no guidelines about what is a desirable size for DB extents. For example:

Is there any advantage in having all extents of (approximately) equal size?

Is there any reason to limit an extent to 2GB?

Any wise words would be welcome.

Ron.

 

[toby.Harman]

Q. Advantages in having all extents of Approximately equal size?
A. The DBA can say "I have 43 extents of 200MB each so my database is roughly 8.6GB. That's about all!

Q. Is there any reason to limit an extent to 2GB
A. History! Is there any reason to make it bigger than 2GB? I don't think so but this is a purely personal preference! I tend to stick to extent sizes of between 150MB and 2GB, depending on the total database size.

I don't generally like having more than 50 extents, because I find that a little unwieldy! That doesn't mean I wont and haven't but I prefer not to! I also prefer to have a minimum of about 3-5 extents, but again, this is not a hard and fast rule.

Wise words welcome?
Meddle not in the afairs of dragons, for you a crunchy and taste good with ketchup!