Re: raid 5

Howard,
It's important to remember that the Oracle server use its multi-block read capability only on full-table scans. So, for any access other than a full table scan, multi-block reads are irrelevant to our decision making process. This means that for indexes, rollback segments, and tables that are never read sequentially, there is no need to worry about extent sizing for multi-block I/O. For those segments, if you do choose extent sizes that are integral value of db_file_multiblock_read_count, you put the whole issue to rest. Conveniently, most administrators use db_file_multiblock_read_count values like 8, 16, 32, 64 and so on (powers of two) that work perfectly with extents whose sizes are chosen from the set 2k, 4k, 8k, 16k, ...

howard wrote:

> hi
>
> i have one database running with 2K db block size
> on a raid 5 machines with 6 columns, 32K os
> block. what value i should set for the db file
> multiread count?
>
> thanks
> howard

--

Regards,

Tommy Cusan
MIS - DBA Tech. Support

Oracle Indonesia
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Fax : (62 21) 572 3350 / 60 Received on Fri Nov 06 1998 - 16:31:07 CST