NT Raw partitions seem to provide no benefit

Hi,

I just created a couple of partitions on an NT server (NT 4 SP5; Pentium III
350MHz, IDE 6.4G drive). The database is in noarchivelog mode, RDBMS 7.3.4.5.2. for NT. This is a test machine. Both partitions are identical in size, and on the same physical disk. Both
partitions are 15M in size, one is a raw partition, one is an ntfs partition.
Now.
I put the same table into each of the two partitions, 188,266 rows. When I do a full table scan of the table, the result is the same every time:
20 seconds on the ntfs partition, 21 seconds on the raw partition. I created an index and did a select * from ... which would make Oracle ignore
the index anyway, this time I got 20 seconds for each partition. Then I did
select indexed_column from ... with no where clause. Again it should just
do a full table scan, I got 20 seconds for each partition. Then I did a

select indexed_column from ... with a where clause containing temperature/2
= trunc (temperature/2,0). Times were 2 seconds for each tablespace. Then I did a select temperature from ... where temperature in (22, 23.1,

..., 27.2) and got 2 seconds for each tablespace. The tables in the tablespaces are called raw_table and ntfs_table, and I

double-checked my sql script for the test, it indeed queries two tables and
not the same one twice.
I even increased db_file_multblock_read_count from 8 to 16, and it did nothing for the full table scans: I still get 20 seconds in each tablespace.
Am I missing something here?
I know that a table with 188K rows is not large, but I would have expected
to see at least a 10% difference between the raw parititon and the ntfs partition.
Did I forget to set a registry setting somewhere? Is NT forcing all I/O

calls to go through the kernel and the file system routines even if Oracle
is writing to a raw partition? Is it because I am using IDE drives that I
cannot see a benefit?

If I see no difference on this test machine, I don't see why anyone would
bother implementing this scheme on production servers. Hopefully I forgot
to do something and the raw partitions do make a difference.

Ironically the Oracle technical paper explaining how to set up raw partitions on NT starts by saying that significant performance benefits can be achieved by placing redo logs and datafiles on raw partitions...

Have you placed your datafiles on NT raw partitions? Did you see any benefits? If so, what did I forget to do??

TIA Pat. Received on Sat May 20 2000 - 00:00:00 CDT