Re: multiblock_io count on NT

alex smith wrote in message <66eafd$j6s$1_at_newsd-144.iap.bryant.webtv.net>...
> Hi everybody,
 

> I am a newbie to Oracle 7.3.3 on NT. Could someone please give me some
> guidelines for setting the initialization parameter for multiblock I/O
> on an Intel box running Oracle 7.3.3 on NT 4.0. Could someone please
> give some advise as I have to install a Oracle ion NT very soon.

Alex,

The goal is to reduce the number of physical reads required to fulfill an I/O request in order to achieve the objective of improved read performance. This can be accomplished by reading as many disks blocks as possible in a single I/O operation into a buffer.
On NT, the largest amount of data the buffer can hold for a single read is 512 bytes less than 64K.
Therefore when 512 is rounded up to the next DB_BLOCK_SIZE integer (assume DB_BLOCK_SIZE of 4K),
a single read will only return 60K of data. To achieve this maximum using 4K blocks, you may set the DB_FILE_MULTIBLOCK_READ_COUNT parameter in init.ora to 16 (4K x 16 = 64K).
Note - this will fill the buffer, but the database will report it as a value of 15 as shown in the query
SQL> select value from v$parameter where name = 'db_file_multiblock_read_count';
Value

Regards,

Craig M. Wall Sr. Oracle DBA / Manager of Oracle Technology - C.I.S.A. Received on Mon Dec 08 1997 - 00:00:00 CST