Large Block Chunk Size for LOB column

Question

Oracle 10.2.0.4:
We have a table with 2 LOB columns. Avg blob size of one of the columns is 122K and the other column is 1K. so I am planning to move column with big blob size to 32K chunk size. Some of the questions I have is:
1. Do I need to create a new tablespace with 32K block size and then create table with chunk size of 32K for that LOB column or just create a table with 32K chunk size on the existing tablespace which has 8K block size? What are the advantages or disadvatanges of one approach over other.
2. Currently db_cache_size is set to "0", do I need to adjust some parameters for large chunk/block size?
3. If I create a 32K chunk is that chunk shared with other rows? For eg: If I insert 2K block would 30K block be available for other rows? The following link says 30K will be a wasted space:
[LOB performance|http://www.oracle.com/technology/products/database/application_development/pdf/lob_performance_guidelines.pdf]
Below is the output of v$db_cache_advice:
select
   size_for_estimate          c1,
   buffers_for_estimate       c2,
   estd_physical_read_factor  c3,
   estd_physical_reads        c4
from
   v$db_cache_advice
where
   name = 'DEFAULT'
and
   block_size  = (SELECT value FROM V$PARAMETER
                   WHERE name = 'db_block_size')
and
   advice_status = 'ON';
C1     C2     C3     C4     
2976     368094     1.2674     150044215     
5952     736188     1.2187     144285802     
8928     1104282     1.1708     138613622     
11904     1472376     1.1299     133765577     
14880     1840470     1.1055     130874818     
17856     2208564     1.0727     126997426     
20832     2576658     1.0443     123639740     
23808     2944752     1.0293     121862048     
26784     3312846     1.0152     120188605     
29760     3680940     1.0007     118468561     
29840     3690835     1     118389208     
32736     4049034     0.9757     115507989     
35712     4417128     0.93     110102568     
38688     4785222     0.9062     107284008     
41664     5153316     0.8956     106034369     
44640     5521410     0.89     105369366     
47616     5889504     0.8857     104854255     
50592     6257598     0.8806     104258584     
53568     6625692     0.8717     103198830     
56544     6993786     0.8545     101157883     
59520     7361880     0.8293     98180125     

Answer 1

With only a 1K LOB you are going to want to use a 8K chunk size as per the reference in the thread above to the Oracle document on LOBs the chunk size is the allocation unit.
Each LOB column has its own LOB table so each column can have its own LOB chunk size.
The LOB data type is not known for being space efficient.
There are major changes available on 11g with Secure Files being available to replace traditional LOBs now called Basic Files. The differences appear to be mostly in how the LOB data, segments, are managed by Oracle.
HTH -- Mark D Powell --