My DB is 7.2.3 on Dec Alpha/2000,1 CPU, Physical memory 256MB,  with Dec
UNIX.

  I want to increase the db block size from 2k to 8k during the exp/imp
recently.

  I just wonder that  increasing the blocksize will/won't improve performance
????

  Besides,do I need more memory if I change db blocksize ?? more storage for
importing the original database ??

Remember that when you change the blocksize, you MUST recreate the Oracle
Database from scratch, so your export/import is required.

As to whether performance will improve, is dependent upon the application. In
general, a smaller blocksize is recommended for OLTP systems, with the larger
blocksize >= 8k is recommended for DW/DSS systems.

One thing to remember as far as SGA is concerned, is that the DB_BLOCK_BUFFERS
parameter is specified in Oracle Block Size, so if the Block Size is increased,
then the SGA will also increase in Memory requirements. i.e. 1000 Buffers at 2K
requires 2Mb, but at 8K requires 8Mb's. However, you will get more data in an 8K
block so the number of buffers could be reduced, but probably not bt 1/4.

Rgds
Andrew

If you have a few users only, 256MB RAM will be OK; otherwise, increase you
RAM size !
Assume that you have 50 on-line users, I recommend you increase the RAM size
to at least 512MB !